Ok - I'm working on my (new to me 89' Volvo 240, LH 2.4)

I have done a lot of general maintenance items, see list below.

In the last week or so it has developed an extremely rough idle, to the point it is very difficult to drive. Currently throwing code 2-2-4 (ECT sensor), however it’s a new sensor, and the ECU appears to be showing correct resistance per temp graph in Bentley.

The things I have not yet done: test the cold start injector, check brake booster for vacuum leak

Is there a way to check the ECU itself??

I'm interested in looking for a 951 ECU, from what I've read it does not require the cold start injector - one of the prime suspects...

Recent work:
Replaced in-tank fuel pump
Replaced fuel filter & check valve, also checked operation of pump
Removed & cleaned injectors – new o-rings, pintle caps & filter baskets
Spark plugs, cap & rotor, plug wires
Air filter
Cleaned out the flame trap, removed separator & installed with new o-ring
New Oxygen sensor
New engine coolant temp sensor
Swapped in different IAC valve
Swapped in different AMM
Swapped in different fuel pressure regulator
Cleaned throttle body


Thanks for your inputs, definitely appreciated.

Mike
88' 240, sold @ 250K miles
98' 70GLT, sold at 225K miles
95' 940T, limping along in NM (son's car)
98' V70GLT - my mistake, sold at a loss...
89' 240 - just getting acquainted

This thread is so long I'm just replying to the original message. My browser is struggling to display all the messages.

The shop I had the car towed to Friday spent 4 plus hours troubleshooting the issue. Just before they closed he told me they would have to finish it today, Monday June 25. He did say it was a very tricky problem. Turns out the in-tank fuel pump is not delivering sufficient pressure. Either I installed it incorrectly, or the pump itself is bad. I'm leaning toward a bad pump, I followed the directions to the letter, including using a small pipe cutter to shorten the intake tube - I bought the high performance pump from IPD which is about an inch longer.

So, literally hundreds of dollars later (at the shop), the pump I installed late May will be replaced or reinstalled. I'm fine with the money spent replacing parts particularly since my daughter will have this car away at school. I wanted her driving something safe & reliable. The 244 reputation speaks for itself on safety. I've eliminated the major gremlins from bugging her for the next months maybe even years.

The main lesson I learned, documentation! If I had recorded the date & mileage when I installed that pump I would have caught this within a week, 2 at most. I'm usually very good about recording all maintenance, but haven't bought a little notebook for this car yet...

Question on checking fuel pressure, not on this car but my Audi and a friends Saab. The fuel rail has a Schrader type valve - the tester I borrowed from O'Reilly did not depress the valve stem when connected. Should I remove the stem in order for the gauge to measure the pressure?

Thanks for all the advice & suggestions

Mike

The in tank pump does not do anything but keep fuel flowing to the main pump, so it doesn't need much pressure. The main pump provides operational pressure to the injectors.

It is possible to wire the in tank pump backwards so it does not work in the right direction.

Dan

Art, Dan, Phil, All,

The in-tank pump was wired correctly, and installed correctly - however there was one fatal flaw, self inflicted I must admit. I reused the rubber fuel hose from the pump to the sender assembly - the tube inside the tank. Well - that hose split so the pump pressure went partially to the main pump, but partially just recycled back into the tank!! The shop told me it was likely caused by the higher pressure of this pump versus the stock pump.

All I can say is, unforced error on my part.

The 2 big lessons for me:
1. Document when you replace parts & pay attention. I suspected I may have upset something when I was doing routine maintenance, but didn't make the connection.
2. Don't reuse stuff that you can easily replace, like rubber hoses/tubes, belts, etc. The pump came with a new hose, I don't recall thinking anything in particular about not using it, I already had the new one and couldn't send it back anyway. My inner Scotsman failed me.

Thanks for all the troubleshooting tips, hopefully others will learn from my mistakes.

Mike

Hey Mike,

Though I've felt sympathy for your long pursuit, I cheer the candor with which you are sharing your experience. It is a very good explanation you've given, and I can, without photographic detail, picture the rip in that neoprene connector between your "upgrade" pump and the modified outlet tube in your tank sender unit.

That connector, or hose, is something I wish I had stocked when they were available, instead of having to use the expensive and bulky 30R10 submersible 5/16" hose.

How do you feel about the IPD sales pressure to upgrade? I understand they wanted to find a reliable pump to sell their loyal fans, and have read many proudly told stories about how much sense it makes to Walbro your Volvo, given the spotty rep the AC/Delco and its copies have made for themselves. Also there's a certain appeal (to some) for the hindsight view that the automotive engineers who came up with the original design had their heads up antique rear ends, after all, it failed, after 30 years.

As you probably know, I've been In The Tank a dozen or so times before, and continue to watch carefully the performance of five family fleet LH2.4 240 Volvos in daily use, so it makes sense that I not only have some parts on the ready, but also some of the tools to help me know which parts need replacement.

I've also some Scot blood (Mama's side) to keep me on the path of frugality, and so feel compelled to get the longest performance from the least expenditure. Tools and education, or as I have found, education and tools, are my stubbornly held friends.

The very first tool I found important was for measuring fuel pressure. To make a fuel injected car run, the amount of pressure behind the injector is critically important. It would seem to be a simple matter of connecting a bourdon gauge to the fuel rail, but after making the rounds of the local auto parts stores pawing through their adapters and fittings, I could not find what I needed to make that connection. I needed education. I turned to the Internet (1999) and found this bulletin board. Here, I found help in the suggestion that I get a spare fuel rail from the junk yard to make an adapter from. Here's what I cobbled together and continue to use today.

Since then, I come back here to try to pay back.






--
Art Benstein near Baltimore

I had no Monet to buy Degas to make the Van Gogh.

Art,

I replaced the in-tank pump based solely on not hearing the original pump hum when powered (key on but car not running). As for the difference between the IPD high performance pump (or whatever they call it) and the stock pump I can't tell the difference. I'm somewhat relieved that the pump itself wasn't failed - though again I am kicking myself for not replacing the little hose. Interestingly that in-tank pump is not really that difficult to access, I bought the bung not tool years ago with my first Volvo 245 and decided that and the crank holder tool were worth keeping, even after I sold the original car I used them on.

Last weekend I started helping my daughter's boyfriend with his Saab 9 3 that isn't running. Saab seems to be a little less maintenance friendly than Volvo - if his in-tank pump needs replacing you literally get the tin snips (or Dremel tool) to cut back sheet metal to gain access to the top of the pump! Kind of like Audi, "hm - I know, let's mount the thermostat in a plastic housing and attach it to the block!" Guess it keeps people coming back to the dealership...

I like your fuel pressure tool, homemade tools are great! Gets the job done.

I really appreciate your insights on the forum.

Mike

highly unlikely a pink label would fail now after nearly 30 years. most that were going to fail did long ago.

look for vacuum leaks........around the intake manifold gasket would be a prime candidate or just replace it for under 10 dollars

check fuel pressure but art already mentioned that

The pink label syndrome is no fuel pump, but like all old electronics it can have ordinary non-syndromic defects with scattered symptoms. I agree with your plan to find a -951, not because of its different method of cold start enrichment, but because you have no other way to know if the ECU is at fault but to substitute one you know works. Same goes for the AMM. All owners of LH2.4 cars should acquire spares of these two items while one has the luxury of time to shop.

My first approach to real troubleshooting would be to measure the fuel pressure and observe the response to A/F ratio by the switching action of the oxygen sensor. Just the list of new or "different" parts replaced is not enough to base any conclusion.
--
Art Benstein near Baltimore

If you lend someone $20 and never see that person again, it was probably worth it.

Thanks Art!

Thanks for confirming I'm on the right path. I did notice from the Volvo ECU page that my son's 940T (95') with the 954 ECU would work - unfortunately he is in CO for the summer and I'm in WA state.

Is there a reliable online source? I hesitate to use EBAY.

Thanks

Mike

I keep posting this parts source....worth a call real people on the phone

http://www.voluparts.com/

Mike,

I believe there is one for sale in the Brickboard classifieds.

Ted has a point about the intake manifold. A chunk can fall out of it causing sudden uneven vacuum. I've seen it. And without extensive troubleshooting, I tend to lean toward more simple explanations like a vacuum leak or leaky FPR.



However, the theory about the cause of the pink label syndrome is not age, but externally caused. The theory has it the signal and power grounds, separately made at the fuel rail mounting screws develop voltage drop in corrosion, and if not there, at the splices just beyond the vinyl sheathing in the engine harness where those two ring terminals lead.



The hybrid circuit inside the ECU was vulnerable to a voltage difference between those two circuit grounds until the hybrid was revised more robust by Bosch and incorporated into the white label -561 and, of course, all the -9xx series then in production.

Those grounds might have a tie-in to your contradiction between ECT code and resistance measurements. You could repeat the check, but use a voltage measurement instead of resistance measurement to verify what the ECU sees from the ECT in operation. Here's a chart relating that voltage to the temperature.




--
Art Benstein near Baltimore

If you tell the truth, you don't have to remember anything.

Thanks all for your insights.

Tonight I tried squirting propane around the intake manifold with no change - it was difficult due to the motion of the engine. I should mention the motor mounts are very bad, I have the replacements - just haven't gotten to them. However this also makes me wonder about other potential wiring issues caused by vibrations.

I also did the voltage checks using Art's graph. This was revealing:

I measured temp of the thermostat housing using an infrared thermometer as a point of reference.

thermostat housing 33C, pin 13 measured 0.6 mv
warmed up engine for a few min
Thermostat housing 43.6C, pin 13 measured 0.6 mv; resistance 746 ohms

I didn't think to check resistance in the first reading (33C), took resistance at second since the voltage had not changed. Note also it was extremely low, assuming the graph is volts, mine was 0.6 mv, 0.0006 volts.

Since the ect is new, I'm suspicious of the wiring. Though could also be a bad ect out of the box, that seems unlikely.

Any value in checking resistance from ecu pin 13 to ignition ecu pin 2? I don't know the internals of the ect.

I'll follow up on the 951s tomorrow.

Thanks

Mike

Hi Mike,

The graph is as labeled, in volts, not millivolts.

The voltage is measured in-circuit, backprobing the pin at the ECU connector with the car running. Resistance measured with the ECU connector disconnected and (always) with the key off (power disconnected).

The black ECT sensor has two identical thermistors wired to the two pins with a common ground through the sensor body to the cylinder head. If you made the measurement from ignition to fuel harness, you should read 2x the value in the chart.

If you made the voltage readings correctly, you've proved either a poor contact at the ECU connector, or a fault in the ECU, as that voltage is supplied by the ECU from its internal 5V source.

This curve shows what voltage should be versus resistance and how it is derived by the ECU internal source.


--
Art Benstein near Baltimore

Some days you're the bug; some days you're the windshield.

So today I received both the -951 ecu, and the new intake manifold gasket. Swapped in the -951 ecu for the pink label ecu and... the rough idle continues. However I now have a more reliable ecu, so I've got that going for me - which is nice.

Tonight I've been taking things apart to check on the manifold gasket. Well trichard was on to something. The gasket split between cyl 3 & 4, half sticking to the head. But at the forward edge of cylinder 1 about 120 degrees of circumference was broken off & missing completely!

I'll finish it up tomorrow - pretty confident this was the root cause.

Thank you all for your inputs. Guess I'll hang on to the pink label ecu as a spare but it won't go back in unless there is a serious problem.

Thanks

Mike

Art,

I took measurements correctly tonight, backprobing ecu pin 13. I also measured the thermostat housing temp again for reference.

Initial start of the car
thermostat housing 22.4 deg C; pin 13 measured 2.2 volts dropping quickly

after running 4 minutes
thermostat housing 36.6 deg C; pin 13 measured 1.34 volts

Based on the first graph you posted these numbers look good.

I did order a 951 ecu; think I will also get an intake manifold gasket.

Could a bad cold start injector cause idle issues past the cold start phase?

Thanks

Mike

OK, so the ECT looks good. What about the ECT code being set? Is that still the case? If so, I'd wait for your replacement ECU if you can manage that, and then ensure the code is fixed by the replacement. Then, if it is, verify that putting the old -561 back in, the code returns. This is diligence due.

As for the speculation about what failed component can cause idle issues, I have no suggestions. If a CSV were to be stuck open, sure it would flood the engine. Just as easily, a leaking FPR or fuel injector would do the same. If you're thinking the -561 is keeping the CSV open, just pull the electrical connector to the valve to eliminate that.

I would measure fuel pressure and check the oxygen sensor's response. Quite frankly, I don't have much faith in the common suggestion to use propane, water, carb cleaner, or whatever to find vacuum leaks in a system where the computer instantly adjusts idle speed to compensate for small variation. Maybe you'll find a big leak that way, but I never have.

On the other hand, I've never regretted the time it takes to put on a new intake manifold gasket after feeling the old one crumble in my hands. It is really an easy job if you're careful not to drop the very last nut by the oil dipstick. Use a magnetic retriever to help. Eight nuts with a 13 wrench and one bolt (12 wrench) at the support bracket.
--
Art Benstein near Baltimore

Expert: An "ex" is a has-been and a "spurt" is a little drip under pressure.

Thanks Art,

I have both a 951 ECU (per Dan's post) and new intake manifold gasket coming in the next days/week.

In addition to changing those I'll be changing the engine mounts probably a week later.

I forgot to reset & check the ECT code, will get that tonight.

Once I get the intake gasket & ECU replaced I'll report back.

Question on the -951, should I disconnect the wiring (cap & stow) the connector from the CSV? I'm assuming I can just leave the CSV in place with fuel line attached.

Thanks

Mike

Mike
That was a great deal on that ECU!

Changing the intake manifold gasket is straight forward, basically just remove the nuts and bolt and pull the manifold back from the head far enough to remove and replace the gasket. You may need to loosen or remove a bolt or two from the bracket holding the IAC valve.

I don't understand what you mean by cap and stow the ECU?

Dan

Hi Dan,

I think Mike is asking what to do about the cold start valve when he replaces the -561 with the -951. Good question with an easy answer. Do nothing. The -951 simply has no output to that wiring.


--
Art Benstein near Baltimore


Duct tape is like 'The Force'. It has a light side and a dark side, and it holds the universe together.

The saga continues - to a lesser degree

Ok, so I installed the -951 ECU and cleared the initial 2-2-4 ECT sensor fault code.

I installed the new intake manifold gasket (the old one had a large piece broken off & missing).

The extreme rough idle is now gone. However it is still not running well, feels like limp home mode. Give it gas & it hesitates, thinks about it, then does go to a limited extent but really fighting me all the way.

I'm thinking either fuel starvation or some type of electrical fault. It has not set any new codes after the 10 minute drive last night.

I'm wondering about:
Can the distributor be turned slightly resulting it poor ignition timing?
Ignition coil?
Does the -951 require a specific AMM???
Spark plugs fouled? (though only have 1000 miles on them)
The engine mounts are toast - wonder if all the shaking is causing an electrical issue somewhere??

I'm out of town till Thursday night so can't do anything till then.

Anything else I should check other than Fuel pressure?

Thanks

Mike

First, what Dan says is a must. Check the AMM's pins, and if the boot is torn, suspect moisture has compromised the connections.

The AMM is matched to both the -561 and the -951. The 93's came with -951s using the same -016 AMM.

Second, the dizzy does nothing but point to the spark plug. If someone before you has removed the lock for its positioning and twisted it, sure, it can cause missing at extreme adjustments made by the computer, but this would require a mistake by a previous "fixer" who didn't know how it worked.

Ignition coil is rare, but when they go it usually shows up after some warm-up because the coil heats up.

I still say you will know how it is running if you know the fuel pressure and can observe the oxygen sensor switching. Otherwise you're back to swapping parts.
--
Art Benstein near Baltimore

Never miss a good chance to shut up.

Thanks Dan & Art,

I did notice the AMM that came in the car has a different shaped wire element inside, the spare I picked at the boneyard has the trapezoid shaped element. The spare is somewhat dirty so after swapping them (with no apparent difference before - (due to failed manifold gasket) I put the original AMM back in. I’ll switch back Thursday night when I get home. I may even have some AMM cleaner, or I’ll get some.

I’ll report back.

Thanks for your inputs - I know I’m close to being done, with this issue. There are other things of course with a car of this age & mileage, just rolled over 219K.

Mike

Hi Mike,

The hot wire shape changed in production of the -016 AMM by Bosch, but regardless of which style you have, each has the same performance specification. I'm a little leery the commercial MAF cleaners are a good way to treat your hot wire AMM. If you search the archives here, you'll hear both success and "I ruined it" stories. It may be my perception, but I believe the latter, despite the stigma of confession, wins the percentage numbers. Of course, technique might play a large part with such a delicate instrument. If I had your challenge (and I have in the past) I'd stick to cleaning the electrical contacts, especially on the harness connector, and leave the cleaning of the hot wire to the burn-off cycle provided by the ECU.



--
Art Benstein near Baltimore

If you send me $20 I'll send you a how-to explaining how to make $20 from people on the internet.

Well - hate to say it but things have not gotten any better. The basic limp home mode persists. Here are the most recent things I've tried:

Swapped in different AMM (unknown pedigree)
Purchased and swapped in a third 016 AMM last night (also unknown pedigree)
Back probed all 5 AMM wires from connector back to gnd, FI relay, and the 3 to the LH ECU. All showed good continuity (maybe 0.2 ohm - probably within the error of my meter).

Keep in mind I have also put in new ECT sensor, new O2 sensor, -951 ECU, swapped in different IAC valve and FP regulator.

Today when I took it out for a test drive it set code 1-2-1 in socket 2 (signal from AMM), this is when I cleaned all the dielectric goop from the connector & on the AMM itself, also when I back probed all the AMM wires.

Tonight, barring any additional troubleshooting tips I receive, I plan to change out the engine mounts. This is about the only other thing I can think of - that the engine shaking is causing a loose connection somewhere - lost signal forces it into limp mode which in turn exacerbates the vibrations since the engine mounts aren't doing their job.

Anything else I should be checking?

Does the 89' with LH 2.4 have some type of rpm sensor (impulse sensor??) or something that if jiggled and signal loss could cause limp mode?

Thanks again for your insights.

Mike

Hi,

I have been missing out on thus thread. I vote to change out the CPS,
IMHO, they are just as untestable as the AMM and about as reliable or less.

Make sure you put the new one into a nice clean holder as the distance from is important. The holder should hold it in the proper place up and down but I have read that sometimes shims are involved, though I have never seen any?

Phil

Last night I replaced the cps thinking I had finally found the smoking gun - to my dismay the limp home mode persists.

I tried all 3 AMM just in case it was caused by the combination of bad AMM and cps (granted I can't vouch that any of these AMM is good, one was on the car, 2 from the boneyard - I'm just assuming not all 3 are likely failed).

Plan is to have it towed to a Volvo shop tomorrow. Both my wife & daughter have been very patient while I worked this the past few weeks. Daughter will take the car to college in the fall.

A couple last questions, last ditch efforts for tonight:

Can a failed signal to the EZ-116K ignition computer throw the car into Limp Mode?

Are the EZ-116K computers prone to failure?

Appreciate your inputs. Years ago I had issues with my first Volvo, 88' 240, and went through similar stages of trouble shooting. Don't recall the final cause - just the frustration.

Mike

Hi Mike,

First, let me apologize to you for your frustration in trying to solve this by changing parts. Surely we all lead you and others to believe troubleshooting is just an elimination process of finding and changing the bad part, using a list of the "usual suspects." You've changed a lot of them.

For your questions: The "limp home" mode is peculiar to each of the engine controllers, and it acts in different ways.

Ignition: For instance, the EZK ignition system will allow safe limits to spark advance in case the knock sensor signal is absent. There isn't any limp home correction if the CPS is intermittent, because the computer cannot know where the engine is without that signal being correct. No, the EZK computer is very robust and we never hear of one being confirmed faulty, while its amplifier (in front of the battery) is a more common trouble with various symptoms between no spark and most-of-the-time spark. The coil could be faulty and give the same performance, yet most of my experience is with wiring harness connections and terminations causing the intermittent troubles. This "harness" is the one part that is never swapped, of course.

Fuel: LH2.4 limp-home is set rich to protect the motor. You'll note a 113 when it is confirmed set, and often an accompanying 232. There are many things that can cause it to lock into limp-home, as we've already discussed. It does so when the air/fuel ratio, as reported by the oxygen sensor and the fuel computer's knowledge of spark timing don't fall into correctable limits. Your Volvo mechanic will be able to check fuel pressure and oxygen sensor response. Please post back what she finds.

--
Art Benstein near Baltimore

Experience is something you don't get until just after you need it.

Art,

In the midst of the frustration I must admit I also enjoy the challenge. And frankly working on the 240 is Much easier than my daily driver, an 02' Audi A4 with the 1.8T. For some reason Audi decided the thermostat is better placed on the block - down below the alternator, Throttle Body etc. So, no worries - I trust you guys, you make the Brickboard such an excellent resource!

Yes, I'll report back on what the shop finds. Unless on the off chance I get lucky with Phil's suggestion of checking the AMM connector.

Thanks

Mike

"Unless on the off chance I get lucky with Phil's suggestion of checking the AMM connector."

Okay, though I thought you did that a week back...

June 5

Good idea to double check. A paper clip makes a good tool to release the pins.
--
Art Benstein near Baltimore

It seems like a lot of suppliers are only interested in plugging the hole with a part, rather than making sure the part is of high quality. -Benski

Art, Phil, All,

So - the journey may soon be over!

Art - you called this from the get go. Looks like the main in-line pump was on it's way out. I was so fixated on some type of electrical issue throwing it into limp mode that I wouldn't consider fuel pressure. Actually now that I think about it, the car may not even be in limp mode, just exhibiting the same behavior...

I back-probed the connector for the AMM (literally checking one side to the other) all looks good. Made an appointment to get the car into a local Indy shop I've been to before. When I asked what he would be looking for, after telling all I have done, he said fuel press and O2 sensor switching - exactly what Art suggested a number of posts ago.

I checked with OReillys, they loan out fuel press testers. At that point I finally decided it's worth the effort before I pay to get it towed on Friday. Had to get a fitting & short hose to make the connection at the cold start injector connection on the fuel rail. Once I hooked it up, nothing, pump wouldn't run & car was a no start. This morning I went out & tried it again, pump came on providing about 10psi at key position II. Tried starting & got it to catch briefly but again very low pressure. So - I ordered a nice Bosch replacement pump and am looking forward to finishing this job up in a few days.

Once I replace this pump all fuel components will have been replaced or cleaned (injectors, IAC valve). And I've swapped out a few other things so feel pretty good about turning my daughter loose on the road. Now if I can just figure a way to disable her phone so she isn't checking texts, changing the song, etc....

I'll give another follow-up once I get the new pump in.

Many thanks to all the responders.

Mike

Lars 88' 240, traded @ 250K miles
Son of Lars 98' S70GLT, traded @ 225K for the Audi
Charles 95' 940T, tooling around CO and NM - son's car
Silver 98' V70GLT, my mistake, sold at a loss
Sven 89' 244 soon to be cruising the streets of western WA again!

Sorry for the long delay between updates, I've been busy throwing more parts at the car hoping for a better outcome. I'll list them separately below. The car is now at a shop in Seattle, towed away this morning...

Main Fuel Pump - I had previously replaced the in-tank pump and filter. Last Friday I borrowed a fuel pressure gauge from O'Reillys - this is a great service btw. Car was showing only 10 to 11 psi. Thought I found the smoking gun. Ordered a Bosch pump & installed it Wednesday night - no changed, car still runs as if in Limp Mode.

Yesterday morning it started to backfire at around 25 to 30 mph when I tried to accelerate. It dawned on me perhaps the catalytic converter is plugged! So ordered one. When I pulled the old one off I tried to blow through it, no apparent blockage. Talked to the Indy shop, he said that won't really rule out a bad cat. So last night I installed the new cat - no changed, car still runs as if in Limp Mode. I had already replaced the O2 sensor.

I had previously taken the hot air duct off the airbox, decided to remove the thermostat and flapper door last night. And it was in the closed position so that was failed. I did notice a difference in how the car runs - however it still bogs down at 25 to 30 mph. It feels like a governor on a golf cart, the timing feels off & it tries to stall out.

My daughter (this will be her car at school in the fall) and wife have patiently waited while I dabbled in all these efforts - but I'm out of ideas, so away it went. One thing I didn't check and suspect is the wiring from the ECT to the ICU (ignition computer). When I replaced the ECT the wiring felt flimsy - as in maybe only one wire?? However I couldn't see it very well. Signal to the ECU was confirmed by change in temp being picked up at the ECU, so maybe the wire to ICU is broken...

I'll post after I get the results from the shop.

Thanks all for your inputs

Mike

Hi,

I looked thru the threads but can't seem to find it. Have you ruled out any vacuum leak from the brake booster?

When you replaced the intake manifold gasket things seemed to run a bit better. So it could be 2 vacuum leaks in 1 occasion. With a partial leak the brakes could still be working. So working brakes doesn't rule it out.

Thru all these troubleshooting do check again the basics like fouled spark plugs. The ECU might try to compensate for the vacuum leak by running rich and affect the your new plugs.

Regards,
Amarin.

If you are getting to 25 - 30 mph before it bogs down I don't think that limp home. Limp home for me was it was very difficult getting to that speed and required a very light foot on the accelerator. Once moving it stayed moving fine but if you wanted to accelerate beyond that it was still very difficult. I never tried to go much faster than that as I was on local roads, never tried in on a highway.

I hope the shop can find the problem and fix it, are they experienced with this generation Volvo?

Dan

I believe limp home mode is only related to an AMM failure.
Dan

Dan,

I was wondering about this - what exact conditions set the limp mode?

Had thought perhaps it was fuel pressure related (or the air being choked) causing my issue - I'll address both in my case in another message.

Thanks

Mike

Limp home mode occurs when there is a signal loss from the AMM to the ECU, the ECU to goes into limp home mode. It could be from a bad AMM or wires or connection problems from the ECU to the AMM.

You can make the ECU go into limp home by disconnecting the AMM connector while the key is out of the ignition switch. Don' disconnect or plug in the connector with the engine running or with the key on.

Have you looked for air leaks in the accordion like tube between the AMM and the throttle body?
Dan

My guess is that is probably true for a 240. In newer Volvos it can happen when the engine or tranny computer throws certain codes. More or less a self-protective measure for that particular component.
--
Will I buy another Volvo??? We'll see....

This is a good time to replace the fuel filter!
Dan

Dan, thanks - missed mentioning you in the last message

Actually, I had already replaced the fuel filter & pump check valve. I also turned it on to make sure the pump was working*. Or so I thought. It was pumping fuel though not to spec. I had also changed out the in-tank pump and pulled the injectors. All of this was before the problems started - just catching up on the maintenance.

The inline pump went out on my son's 940 in New Mexico so I didn't want this car to suffer the same fate of a fuel delivery problem. *So just seeing fuel come through the pump, in my mind, was sufficient...

In full disclosure I'm Scottish and stubborn - not the best combination at times...

Mike

I read the post that you think it is the mai fuel pump. That’s believable!

So it was not a Zebra at all but a Scott playing around with his Swedish horse that already knows how to be thrifty!

It’s hard to beat the wisdom of Art!

(:-) Phil

Hi,

Shame the CPS did not change anything.

I agree changing around three different AMM’s the odds should be in your favor of the symptoms changing unless the problem is in the connector itself.
Those pins do push back up in the holder if the tabs inside get weak.
I would run my ohmmeter from the inside to the backside where the wires come out from under the rubber boot.
Give them some good wiggles and except nothing but a closed shorted leads reading.

As far as reliability those two computers, the ICU/ECU are mostly on the good side.
But I have read or it just seems to me, that the 1989 is a little more problematic that the later years in posts made here on the B.B.

I have read only once that the ICU can suffer from high ambient temperatures but that was from Malaysia. They put a computer fan on it and the problem, whatever it was, went away.
If your car has a bad one or if it is the ECU it must be pretty far gone? It does control mixture and is a true middleman.

It seems that the car is hitting with regularity on start up so the spark is getting generated. Your car is not turning off like on another poster I’m working with.
If it wasn’t the CPS giving out any erroneous signals that will go to the ICU, then it turns on the ECU. It is those same pulses that are transferred to the ECU. Those base signals are spread out and run through parts of the program at the same time.
There is a thin line drawn where the ECU makes more crucial adjustments. I think the ECU is what controls limp mode, when it doesn’t like something that might hurt the engine.

So, at this point, you are looking at swapping out these looking for an ECU that is not in limp mode.

With my foot sticking out of my mouth, I still need to mumble out this question to ask. Have you run a compression check to make sure you do not have a stuck open valve. Either by being too tight on the valve lash adjustment or a burnt valve?

Phil

Phil,

Compression check - I have considered that, and been reluctant fearing what I may learn. The valve cover gasket has been leaking oil from before I bought the car 2 months ago - on my list is to take it in and have the valves adjusted & gasket replaced at that time. Yes - I will do the compression check tonight.

I like the idea of checking the resistance through the connector itself. I did check connectivity from the backside of AMM connector to the ECU, but didn't think about within the connector.

As for the other functions, like starting the car, it has no issues. Last night I checked the signal to the new cps through the diagnostic test port - it gets good signal.

I'll report back on the compression & connector checks.

Thanks

Mike

"I have been missing out on thus thread. I vote to change out the CPS,
IMHO, they are just as untestable as the AMM and about as reliable or less."

When it comes to part swapping, suggestions run for office just like political candidates. We get who we vote for. And then, to justify the expense (time and effort) we say the part was old, so it needed it anyway.

What I don't understand is the repeated plea for "other suggestions" and absolutely no remarks on the ones already given.

No shims involved, Phil. But there is a benefit to replacing a working CPS. The water follows the cable into the sensor when the sheath is broken, causing the magnetized core inside to rust and swell, locking the sensor into its relatively fragile aluminum alloy bracket, in a place that is practically inaccessible without dropping the tranny.

I'll vote with you, but for the wrong reasons.
--
Art Benstein near Baltimore

Wisdom comes with age, but sometimes age comes alone.

Art, Dan, All,

Changed out the engine mounts this weekend - forgot what a pain that is with the oil filter... To my surprise the mounts were not that bad - the extreme shaking is more from the poor running condition, limp mode.

I removed the CPS & the outer casing is split open the first few inches above the sensor. New part on order.

Art - the 2 things I have not followed through on are testing fuel pressure and electrical switching of the O2 sensor. I replaced the O2 sensor and most of the fuel system components - less the main pump which I tested when I replaced the filter & pump check valve. Sorry if I missed following up on something else. Can O2 switching be observed with a VOM?

I will post again once I replace the cps. If that is the cause, I'll check my expanding cache of AMM, IAC valves & maybe even swap back in the pink label ECU to start a good set of spares.

Thanks for your inputs - I'm hopeful the cps, as noted in Art's description of moisture intrusion, is the root cause.

Mike

Hi,

Yep, you named it! Root cause.

When you crank the engine over it's the first thing that tells the systems that something is moving.
All the systems base what they are designed do and when, off that signal.

If it's putting out a squirrelly signal, you can expect similar results.

The reason I chose a squirrel for my animal of choice is I have watched them play or get angry at each other. They chatter and circle about so randomly that it's hard to tell the difference where things are going.

If we are not there putting our elbows down on the fender, while holding up our up chin, a best guess is a suggestion from the armchair.

Finding that crack, that is not part of the manufacturing process, sounds very hopeful to me!

Phil

Thanks Phil,

Your description of the squirrel made me laugh.

Have to admit I'm a lot like the dog from the movie Up, just the mention of "squirrel" and my head is off looking in another direction - too easily distracted...

Mike

Art,
The clue to a potential problem with the CPS --- was revealed when Mike posted asking the question " can you turn the distrib to effect timing"

You posted back no... the distrib is empty and has no effect.

Looking back thru the litany of parts swaps that Mike did there was no mention of the CPS...

it wasn't until his last post ----asking about a RPM, did it become apparrent that he did not know that his 1989 had a CPS...which shud have been a least Number 5 on the list of things to check --- with the symptoms exhibited. Way before swaping ECUs and AMMs

"if you hear hoof beats coming up behind you...don't expect a zebra"

HI CB,

My wife, who was misdiagnosed for at least 10 years, and eventually found to have a very rare disease would disagree with you. In fact, in med school they teach, if you hear hoof beats think horses not zebras. As it turns out, my wife is truly a zebra, as are several of her family members.

Phil

CB, you make a good point.
--
Art Benstein near Baltimore

Growing old: It's frustrating when you know all the answers but nobody bothers to ask you the questions.

Art.
at your local library where you can check out DVDs

most anything from ACORN. An Annapolis company that imports "British" TV crime mysteries,
not just from england, but also from Aussie and New Zealand too.
Great Stuff.

Loch Ness last I watched

"..."British" TV crime mysteries..."

Lots of modern Volvos in them too. My fav was the BBC Wallander with his obnoxious ringtone I adopted.
--
Art Benstein near Baltimore

Tuesdays and Wednesdays are Senior Citizen Discount Days at the Waterville Food King.

I really enjoyed Wallander was up there until the end...with the dementia theme....too close to home

Luther and Luther2 Idris Elba goes from driving a 240 to a 7(9)40
There is one before Luther as it starts with an unresolved --from last season scenes. Gritty on the edge copper unlike Wallander

Also seems to have the same voice/music derivation as Wallander...maybe just me

What's that "knuckles bleed.....facing a door that shudn't be there " ?? Wallander.

Have you seen Worricker===Great Stuff 3 full length no volvo's involved.

Bill Nighy reprises his role as MI5 spy Johnny Worricker in the second and third instalments of David Hare’s Emmy-winning spy thriller. Turks & Caicos and Salting The Battlefield follow Page Eight, which aired on BBC Two in August 2011 and starred Rachel Weisz, Ralph Fiennes, Judy Davis and Michael Gambon.

I don't know much about zebras but I have endured a loping idle and a couple of non-threatening obd codes for years swapping parts like a crazy fool only to find that in the end in the process of cleaning the throttle body, I must have torn the gasket.

Good luck, perseverance is a plus.

Marty

Does the 89' with LH 2.4 have some type of rpm sensor (impulse sensor??) or something that if jiggled and signal loss could cause limp mode?.
???????????????????????????????????????????????????????????????????????????

Volvo B230s from 1989 on use a CPS for the ignition timing.

The Crank Postion Sensor

pageda is no doubt correct.

While you are changing the Motor Mts...with the engine a bit lose. Good time to replace it

https://www.brickboard.com/RWD/volvo/1619794/kittys_grey_volvo_replaces_crank_position_sensor_cps_rpm.html


https://www.brickboard.com/FAQ/700-900/FAQPDFVersions/EngineSensors.pdf

Soft, spongy, or broken motor and transmission mounts will lead to increased engine vibrations. This engine isn't extremely smooth when it's running right,

You have a crank position sensor mounted behind the head on the top of the transmission bell housing. Wiggling the wire on one that is going bad usually results in a stall and maybe a no start. Look at the insulation on the wire for missing pieces or cracks, if you see this replace the sensor.

Dan

This sounds like a failing or failed AMM that has sent the system into limp home mode. Your best solution is a known good 016 AMM to swap in and see if it solves the problem. Limp home mode makes the engine very hard to accelerate, I find the only way to get home in this mode is a very light touch on the gas pedal to gradually get the car up to an acceptable speed.

You might want to check the pins in the AMM connector to make sure they have not been pushed back and not making contact in the AMM.


Dan

Dan, Art,

Yes - cap & stow is a term for cap off the wire connector to keep it from making contact with ground.

Makes sense to leave the CSV installed to the intake manifold & to not have to deal with the fuel line. Wasn't sure about the wiring - but if no issues to leave that connected so much the better.

I pulled the intake manifold off my last 240, actually had a gasket for this car but managed to pull the oil separator w/o removing the manifold so sent it back to IPD. Now I ordered it again...

Thanks

Mike

Art,

Thanks for the detailed explanation. My voltage measurements were key on measured between ECU connector pin 13 and ground - ECU disconnected.

Tonight I'll backprobe the ECU with connector attached & engine running. Definitely makes sense so that I'll see what's happening with the ECU as opposed to just checking the wires & ECT sensor.

Great graph!

I'll post results tonight.

Thanks

Mike

Mike
Don't be afraid of ebay, just look for a reputable seller with excellent feedback. But keep in mind the ECU may not be the problem, the failure of your pink 561 ecu usually results in a no start and yours is still running.

If I was running a pink 561 I would have a known good 951 on hand for a spare or just replace the 561 now.

This is a very good deal on one, I have no affiliation with the seller. https://www.ebay.com/itm/Volvo-240-Bosch-Jetronic-ECM-Engine-Control-Computer-91-92-93-Used-ECU/312136765258?hash=item48accd0f4a:g:5FYAAOSwHPNa~gGt

Follow Art's suggestions and see if you can get it running as it should.
Dan

Thanks Dan!

I just ordered this ecu from the link. Great price and as you mentioned he has good reviews.

Thanks

Mike