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1993 245, manual transmission, no EGR. Currently with ECU 280 000 951, and running badly: lack of power, bucking, high idle, 1,100 RPM. Have done all "tuneup" items, recently told that 280 000 572 is the right ECU. Anybody with experience in this?
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Issue resolved! The problem was the MAFS, aka AMM!
Idle is steady at 800, no bucking, no stalling!
As simple as these cars are, sometimes they throw us all off!
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Does your 1992 Volvo 240 with LH-Jetronic 2.4 / EZK116 ignition have a silver accordion like air hose between the exhaust manifold heat shield and the bottom of the air filter box?
Either remove the preheater function by removing the hose and inside the air filter box, the preheater function from inside the air filter box or restore the air filter preheater air filter box thermostat (Wahler PN 70411).
The rest of this text is from a current post about someone and their 1988 240 passing CA-state SMOG inspection.
The preheater air hose connects to the air hose nozzle on the preheater. However, this type air hose, as used on air-cooled VW, is a spiral wrap hose. That hose actually screws clockwise like normal thread onto the air filter box preheat air inlet under and and access obscured by the water pump fan shroud. You can drop the belly pan and route and connect that way with fan shroud disconnected or removal along with the water pump fan (so you do not risk bumping the radiator and bending the heat sink fins.
The reason why the preheater feature is disconnected, that no one ever mentions, seemingly, is that inside the air filter box, upstream of the air filter, is the cold air / preheated air flap valve. It always fails to hot. And all hot all the time means will cause the MAF / AMM to fail, eventually.
The preheater flap valve is controlled by a thermostat. After market is Borg-Warner Wahler PN 70411. I read replace every one to two years.
Else, as you are in OR DEQ-state, where I resided in Milwaukie, all state and federal mandated emission controls must appear to work during OR-state SMOG crazy inspection? You may want to ask at the facebook groups:
- Oregon Volvo Tuners (OVT)
- Volvo Owners of the PacNW
You can replace the Wahler PN 70411 thermostat with the heat shield and preheater air restoration.
Some will create an appearance of heat shield and preheater hose connection. Yet the air filter draws no preheated air. All ambient air intake. Saving your AMM / MAF.
If your environment as enduring severe winters, preserving the air intake preheater function is useful.
You may want to ask for the around 2" preheater hose sections that are I guess five feet long. Secure around the route with zip tie straps. As iPd sells it:
https://www.ipdusa.com/products/5448/105054-volvo-pre-heat-hose-aftermarket-946841
You Tube videos detail the Volvo 240 air box preheater flap valve, how it fails, and how to restore and remove it.
https://www.youtube.com/watch?v=osC0FlLuKEY
https://www.youtube.com/watch?v=FGWXXyXD2ME
https://row52.com/
Vehicle search. Choose Volvo. Enter your Zip. Change the miles from 50 to 100. Yet Rancho Cordova south of Sac seems a distance.
Does that help you? Questions?
Thanks.
Debt-Based Fascist-Enduring Buttermilk Boy (has no buttermilk).
--
Donate NOW! Give your brickboard.com a big DONATION!!! Find the  on brickboard pages!
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That's good news, now get another one so you have a spare!
Dan
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Hi,
Glad to hear you found out it was the AMM.
I said there was no test for them and Art said it is best to have a spares to test with.
Glad to find out you have the LH 2.4 traditional system too! That makes the ECU a safer bet to stay good.
A spare is optional are out there to shop for in your leasure. If you are lucky you can get both for about $30-40 each. Just test them right away before storing.
Otherwise you can pay for rebuilt AMM's or for someone's stash with a slight markup but with a longer a warranty. They should be checked it out when they got theirs from wherever.
Any rebuilt AMM is a mixed bag of worth, but as far as I know, there are some better than others.
Which way did you go on the one you put in? Brand of replacement or rebuilder?
Statistics are always nice, to build up a consensus on, to help keep them in business.
I would suggest revisting the O2 sensor reading after you run the engine for several miles to help clean it of from contaminations. Excessive lean or rich mixtures bothers the life of the sensor.
The readings should hover closely to .5 volts and move quickly around center.
The sensor is what keeps tuning the engine continuously.
I have an LED readout monitor and the lights flicker very fast in the middle of the ten LED tree string.
A ver high sample rate DVM is needed to see it otherwise on a numerical display.
You want sensor hot and the engine is pushing out a steady smooth stream of exhaust, at idle, or above 2,000 rpm for smog purposes.
Happy Motoring!
Phil
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posted by
someone claiming to be CB
on
Sat Sep 7 18:02 CST 2019 [ RELATED]
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You know the story about what all first year medical school students are told the first day of class.
"if you hear hoofbeats approaching, don't think Zebras"
Cheers
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Hi,
I think you need to verify that since you have a 951 it's more likely a LH 2.4 of the same years in sedans. It's very unlikely that an ECU gets gambled with and be plugged into an unknown harness configuration.
The 2.4 throttle switch should click when fully closed and when opened.
On the Wagon manual style vehicles, I cannot speak for! I have not touched any of those.
The LH 3.1 has a variable resistance like a potentiometer control.
The AMM's, as far as I know stopped changing and ended with 016. They are pretty reliable, but we all know how that can go as there is no real test.
I have heard of people trying to do, what they think can make things better and spray them cleaner for " the **** of it!" Then it messes it up to be worse just a short time later. They work right or they don't, its their habit.
The real problem was due to other issues related to air leaks behind the AMM and was then compounded only from those good intentions.
We need to hear more history on the cars condition. There are a few key places to cross off before jumping onto the "bad ECU" bandwagon!
The ECU is fairly bulletproof, by most accounts, unless, it had the misfortune to be under a leaky windshield or wiper grommet behind the glove box.
Be patient before jumping about in front of an expensive parts counter man. Lots of electrical items do not allow returns for guessing experiments.
The LH3.1 was a low production volume experiment on the last 240's.
Phil
Edit: I see you caught the discrepancies and muted my post flat out, pretty much?
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Rest assured that the car's condition has been thoroughly verified and the only possibility left is the ECU.
My confusion at this point is that my Volvo shop (pretty much exclusive 240 guys with 30+yrs experience) say that the car needs a 572 ECU which is specific for the manual tranny. The ECU in the car now is a 951, and since I got the car used I have no idea if that is the right ECU. Other experts are telling me that 951 is the right computer and that it makes no difference if the car is auto or manual. On Ebay several sellers are specifying the 572 as the right ECU for the manual transmission.
So, who to believe? I am trying to avoid buying both computers but so far the "experts" differ.
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Hi,
I’m resting just fine since it’s your car and not mine with the issues. (:)
I’m happy to see you move always from getting an ECU and ditching that questionable pro shop that was probably needing a ski-doo payment this week.
If they could get you to spring for that ECU, they might have another car that really has one of those 572 rare animals.
That car is probably being a dog for them and they cannot figure it it out either!
Good thing you were not a chum, because they had a line on you to be bait!
Phil
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In all fairness, they didn't charge me much for this diagnosis, and never even offered me an ECU-- the only thing they did was a throttle body service. But, I'm very skeptical when it comes to all repair shops, most charge over $100hr and do very little to justify their existence.
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Hi Ted,
I wasn't going to join this thread because Dan explained it so well there was nothing for me to add.
However, it seems you're at the point where you need just a bit more consensus.
Dan is correct.
Dan is correct.
Your shop is mistaken.
If you were to buy a 572 (pricey because of its relatively small range of application) it would not solve your trouble, and you'd have to sell it again to someone with the LH3.1 system.
The LH3.1 system was NOT used in '93 on M47-equipped cars. It isn't the "latest" 240 fuel as some tend to believe, just because the number is the highest. Perhaps the latest in design, but not in application. But where LH3.1 was used in a 240, the M47 was the transmission. Just 90-92 best I know. Definitive identification is the AMM plug -- an LH3.1 AMM has only 4 pins.
--
Art Benstein near Baltimore
Show me a piano falling down a mine shaft, and I'll show you A-flat minor.
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Thanks Art!
This is exactly what I was looking for, a consensus.
So, another 951 to solve the drivability issues?
There have been codes 113, 232, in the recent past, none now.
Much appreciated, as always!
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My recommendation for 20 years has been to keep a spare ECU and AMM - preferably one you found at leisure, before you need one. The idea is to get one cheap at the yard and run it for a day in your car before stashing it, because each of these two items is hard to convict by test and measurement. Substitution is about the only way to eliminate them from the suspect list.
113 is the code you get when the fuel system has given up trying to match the oxygen sensor's output with what it expects. Limp home fuel map. Most common in my experience are problems outside of the ECU. Put it this way, swapping an ECU never once fixed a 113 for me. Once your car sets a 113 you can kinda know whether it is too rich or too lean if you're familiar with the smell of raw fuel.
Reset the computer. Lift fuse 6 for a second if early prod 93, or fuse at battery post if the late.
Be sure your fuel pressure is correct, and the regulator doesn't have a hole in its diaphragm, and your oxygen sensor is working. I think you'll fix it with one of those three issues. But then once it is fixed, look for a spare 951 and 016 AMM anyway. Hate to see them crushed.
If you can't do these things, take it to another mechanic, because these are the basics any shop should have covered first.
Edit: I missed the notion these codes don't show up any longer. I sure hope the ECU wasn't damaged by the shop in the course of their troubleshooting.
--
Art Benstein near Baltimore
A grenade thrown into a kitchen in France would result in Linoleum Blownapart.
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If one can't buy an AMM or ECU "at the yard" (and I like to think of this mythical yard, full of year/model appropriate Volvos, all laden with good parts for a song) where else would you suggest I purchase these?
Thanks!
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Good question. Getting something yourself at a salvage yard is highly dependent on your locale.
For this reason, those with good access to recently junked wrecks of this vintage, have found a lucrative resale market via ebay and the enthusiast forums "for sale" areas.
The difference is the salvage yard doesn't keep track of the market price for new parts, but the folks who pull them on specific makes do, and may price them competitively.
Yes, the yard option was obviously a whole lot better 20 years ago.
--
Art Benstein near Baltimore
"Wise sayings often fall on barren ground, but a kind word is never thrown away."
-Sir Arthur Helps
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So I went to start it after resetting the fuse at the battery and it had a hard time staying running, took me about 10x because it just wouldn't idle without my foot on the gas. But once it stabilized, the idle was at the correct 850 RPM which was the problem before (running high at 1,100), Then the 113 code popped up, CEL came on. The FPR has a faint gas smell from the hose and the O2 sensor fluctuates between .07V and .85V.
I have not measured fuel pressure. Could that be the issue, but if so, why the previous high idle problem?
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There should be a wider range of voltage cycling on the O2 sensor, .2 - .9 volts yours may be tired!. You can buying for a mustang (Bosch 13913) and solder on the Volvo connector for about $40. They work fine and you may be able to find them on ebay for less.
You can guesstimate fuel pressure by seeing if you can pump a quart of gas at the rail in less than 30 seconds it's probably OK. Disconnect the hose at the rail and pump into a milk gallon container.
Dan
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Thanks a lot Art, and Dan!
I'll do what you recommend, definitely not gong after a 572 ECU, convinced that 951 is the right one.
Sadly all this confirms my dim view of shops these days. I don't want to name names but in Portland these guys are an institution and you'd swear they were the "gurus" on 240s if you just drove by the place.
I do have spare AMMs, but no ECUs. I am restoring this '93 Classic, I am much more of a 740/940 guy, since 1986 my first 744TGO...
BTW, There is no noticeable fuel smell, the O2 sensor cycles between high and low voltage as it is supposed to; I'll definitely do the rest!
I'll keep you informed.
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Ted, for me, the oxygen sensor switching regularly is the best health check of the fuel system I know. In fact, it points me away from suspecting anything wrong with the ECU, at least for idling.
Portland, OR, is the mecca for old Volvos, I thought. You've got to have some other options in town.
--
Art Benstein near Baltimore
The average dog is a nicer person than the average person.
-Andy Rooney
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I stay away from shops, in fact I took the 240 to a shop only because it needed an exhaust system and I didn't want to do the dirty work. While there, had them look at the idle issue. I am not fond of shops, and this experience was a proof. No, I am gonna tackle this myself. Thanks!
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Art said it all!
I have 2 - 951 spares but I have 3 - 240s that use them, I don't really expect to use them but glad to have them just in case. I have never had a bad 951. I have had several 016 AMM go bad over the 35 years I have had the 240's and keep 3 spares.
I used to get these parts at the junk yard but they are getting rare.
Art also mentioned the O2 sensor, it does wear out and worth replacing if it's not working properly.
Dan
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You have the correct AMM for the LH 2.4 and the correct ECU.
The connector for the AMM is different on the between 2.4 and 3.1 and are not interchangeable .
The throttle position sensors are also different, the one on the 2.4 clicks open and closed, while the 3.1 does not because it is variable like a potentiometer. What is the Bosch number?
LH 3.1 may have only been installed on manual transmission cars but it does not mean there are no 2.4 manual cars. My 93 M47 is LH 2.4. Regardless of the LH series there is no electrical connection between the engine ECU and the transmission.
Your shop is giving you incorrect information on this one.
What if any OBD codes are triggered and is the check engine light on?
Dan
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Thanks Dan, this convinces me!
Ahh, the "expert" shops!
There have been codes 113, 232 in the recent past, none now.
I have gone over all the tune up parts, even changed the injectors.
So, do you think another 951 would solve my issues?
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280 000 572 is the right ECU for the LH 3.1, and has nothing to do with the manual transmission. I have heard all LH 3.1 240's are manual? What is the bosch # for your AMM?
Dan
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That is the correct one foe LH 2.4, so the 951 ECU is correct for your car.
Dan
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