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Hi all, I'm new here.
A couple months ago I picked up a very nice 1993 Volvo 240 wagon with 142K miles. My parents had one just like it in the mid 80s. I remember riding around in the rear facing seats. Good times.
So far I'm loving Volvo ownership. It's an easy car to work on. To give some more background, I'm a bit of a Subaru nut, 8 years and counting. I track (road course) my STI a few times a year. The STI has been sitting in the garage for over a month on a battery tender because I enjoy the Volvo THAT much. :)
The 240 had a few issues when I got it. The idle was rough and lumpy. It would stall occasionally. There were NOT any check engine lights. The check engine light does function, as it has come on after unplugging the MAF and O2 sensors.
So far I've done the following, which has improved the engine power and responsiveness, but hasn't cured the rough/lumpy idle:
- airbox thermostat replaced - it was stuck half way open so a mix of hot and cold air were entering the airbox. New thermostat confirmed to work post installation.
- airbox flapper cleaned and lubed - moves freely and easily now
- air filter replaced
- post MAF (AMM) tubing replaced with Volvo OE part- there was a crack.
- MAF (AMM) cleaned with MAF cleaner
- O2 sensor replaced with Volvo OE par
- PCV flametrap, filter, and hoses replaced with Volvo OE part
- PCV oil box (under the intake manifold) replaced with Volvo OE part
- FPR (fuel pressure regulator) replaced
- FPR vac line replaced
- PCV vac line replaced
- throttle body cleaned, throttle position sensor adjusted, gasket replaced
- ICV (idle control valve) cleaned
- Intake manifold gasket replaced with Volvo OE part
- Fuel injector o-rings replaced, pintle caps replaced with Volvo OE part
- spark plugs replaced with Volvo OE part
- spark plug wires replaced
- distributor cap replaced with Volvo OE part
- distributor rotor replaced with Volvo OE part
- oil + filter change
- oil cap seal replaced
- oil dipstick o-ring replaced
- odometer gear replaced (it quit on me a few weeks ago)
- seafoam'd via vacuum line (prior to oil change)
- techron fuel injector cleaner run through 2 tanks
- OE tachometer installed
- vacuum gauge installed
Within the last 10K miles, the previous owner had major work done at a local Volvo dealership:
- engine mounts were replaced before I bought the car, I confirmed that are still in good shape
- head gasket replaced before I bought the car. No burning oil or loss of coolant now.
- fuel filter replaced before I bought the car.
- front AND rear seals replaced on the engine before I bought the car.
- MAF replaced ~30K miles ago
The engine is VERY responsive now. No stalling or hesitation when I get on the gas. However, with the car in park or neutral, the engine has a bit of a shake. The shake isn't as noticeable when the car is in "Drive" (it's an automatic).
The RPMs are CONSTANT on the tach (750-ish). The engine pulls about 19 in/hg vacuum. I've been getting between 17 and 20 mpg in town.
I've been trying to track this issue down with no luck. As you can see, I've replaced LOTS of parts, but the engine still shakes at idle. It shakes as if there was a vacuum leak, but I've replaced the entire PCV system as the majority of the vacuum lines.
As I mentioned above, there isn't a check engine light. I've also run a number of the "self diagnostics" on the car and everything checked out fine.
Some potentially odd behavior is that the engine surges when I pinch the PCV vaccum hose (the hose from the flame trap housing to the intake manifold).
Another odd thing is the MAF has 6 pins, but the wiring harness only has 5 female connectors inside. Again, no CEL has been present. The CEL does come on when I unplug the MAF. I found another forum with a post discussing this, but there weren't any right/wrong definitive answers.
What gives? Is the lumpy idle normal?
Thanks!
- Mike
Some pictures:
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Machine Man is referring to the throttle plate stop screw.
You have done almost everything else. I don't know the correct order of the next steps, but I might consider the following:
1. throttle plate stop screw adjustment per Machine Man
2. New ECT sensor (from my reading in the Bentley manual, the main three sensors for engine mgmt appear to be AMM, o2 sensor, ECT sensor)
3. Trying different AMM
4. If you decide to purchase a reman AMM, I had very very bad luck with Programma. The only reman AMM I would consider would be the Bosch unit (look at Amazon.com price--much better)
5. Clean injectors
6. New sock filter on in-tank fuel pump
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Hey there Mike Volvo and welcome to the Brickboard.
Sounds like you have been very thorough. Your car looks great and it is clear you have a lot of respect for the machine. Your work is even beyond what most people here would consider a "zero-mile" service, and you set a great example for what can be done in bringing an old Volvo back to new.
I didn't see in the list what you had done to the IAC, or idle motor. I see it on the bench all cleaned up in a picture. It could still have carbon somewhere in it, or be sticky and require some lubrication. I like using CRC's 6-56 marine lubricant to apply a light oil that doesn't evaporate in parts like this. Seems pretty harmless to electricals as well.
That said, try another one! Get a junkyard IAC along with another MAF, and try the parts for any difference. Even better, try yours in another car with the same family of fuel injection (LH Jetronic 2.4, for automatic cars, 3.1 for most with 5-speeds.)
And I also kind of hate to say this... but they all do that. The 240 and 740 and 940 tends to have a rough idle. The 240 shakes a lot more, because they don't have the hydraulically damped engine mounts of the 700/900. And cheap mounts are not as strong as Volvo ones, for certain. You get what you pay for... Scan Tech is cheap but you will have to do them again in 2-4 years.
I've had 13 240's over the last 13 years, and they've all had some issue with engine vibrations. They just weren't very civilized. My '92 just had a transmission replacement and I'm about to go through a lot of what you're doing, for the second time since I picked it up, to see if some of the roughness can be sorted out.
Good luck with yours!
--Rob
--
89 244GL Turbo // 92 244 M47 \\ 90 745T // 76 242 Convertible
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Hi Rob,
I've had the IAC out a few times. When I was replacing the intake manifold gasket, I sprayed the IAC with carb cleaner to clean it out. Though I didn't apply and lubrication after. It didn't seem to make a difference once I reinstalled it after cleaning. When running the injector/IAC diagnostic on the car, I can hear them operating. I'll see if I can find some of the CRC lube and apply it to the IAC.
I plan to take a road trip to the junk yard this weekend. I just chatted with a guy that works at this particular yard and he seems to be a 240 "enthusiast". They have a bunch of AMMs and IACs that match my part numbers in stock, so I can try those out. I may pick up a spare set of injectors depending on the price. That way I can ship mine off to get cleaned, assuming the used set doesn't improve anything.
Good to know about your experience with the idle, especially form someone who has owned 13! If the AMM, IAC, and injectors don't improve anything I'll chalk it up to "that's they way it's going to be".
Thanks for your input.
- Mike
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Mike,
In case you didn't see this, read MachineMan's last reply on this string. At the bottom of his reply, he discusses how to set the throttle idle screw. This allows the IAC to take over more of the idle function as it was designed to do as opposed to the throttle plate open a tad too much.
http://www.brickboard.com/RWD/volvo/1575507/220/240/260/280/continuing_idle_issue_can_get_past_760_rpm_w_iac_disabled.html
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That's a good description, thanks. When I had the throttle body off, I replaced the stop screw because the original one was sheered off. I also inspected the throttle plate and reset the throttle position sensor at this time. The '93 doesn't have an idle adjustment screw on the throttle body.
- Mike
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Hi Mike, and welcome! Really, really nice looking wagon. Good score! And I love the picture in front of the mural. Sort of the opposite effect that this guy creates: http://petapixel.com/2013/10/14/life-like-miniature-scenes-shot-using-model-cars-forced-perspective-250-ps/
Based on your pictures, I'd say you are much more familiar with 240s than I, even though I've been driving the things for more than 10 years. So I can't offer much.
Only thing I'd suggest, based on you saying it behaves like a vacuum leak, is to pinch closed the vac line to the brake booster. Faulty booster or check valve.
That said though, I'd think a vacuum leak would cause the idle to run a bit high. But checking only takes a second. Well, maybe 5 seconds..
--
-Matt I ♥ my ♂
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Hi Matt,
I've certainly learned alot about Volvo's in the past 2 months! The parts are fairly cheap and I really like working on it in my spare time.
Thanks for the input! I forgot to mention that I did replace the brake booster check valve and brake booster vacuum hose. The brakes seems fine. I have also pinched the brake booster vacuum line to test the booster itself and I haven't seen any change in the lumpy idle.
I've also clamped the vacuum line going into the cabin that controls the vents (and possibly other thing). Again, no change in the lumpy idle.
I'm tempted to pick up a reman MAF (AMM) and see if that changes anything, but I feel that will be a waste of money.
- Mike
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I kinda figured as much...
re AMM, you mentioned having it inplugged (never connecting or disconnecting with ign on)... does it run differently with the AMM unplugged?
If it runs the same, that would certainly be suspect. If there is a change (for better or worse) with AMM unplugged, I'd think the the sensor is okay. But it sure doesn't hurt to have a spare on hand.. I like to keep one in a bag in the car at all times.
--
-Matt I ♥ my ♂
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I think it ran worse with the AMM unplugged. And the check engine light immediately came on. I can't remember exactly, but the behavior was enough to rule out the AMM at the time. Maybe I'll retest that today.
Looking through the service history, it looks like the AMM was replaced twice in the last 50K miles. I bet that's due to the failed airbox thermostat, which doesn't look like it was ever replaced. It's possible that the current AMM is on it's way out due to the failed airbox thermostat.
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While there, check the AMM connector plug's prongs for damage. If one or more happens to be bent, very carefully straighten it out. Spray connector with electrical cleaner.
You mentioned the hose from the flame trap to the intake nipple. Make sure the nipple is clear. If you choose to do so, you can carefully remove the brass nipple and clean the area with a small knife or paper clip. Throw away the flame trap screen. It causes more trouble than it's worth. I have driven my 90 244DL and now 95 855 GLT for years without the screen. No issues.
Check ALL vacuum hoses.
If the engine mounts aren't Volvo OEM consider replacing them with OEM to minimize vibration. Volvo OEM mounts are somewhat soft so they will easily shear off in the event of a major accident allowing the engine to drop to the ground instead of in your lap. Aftermark mounts tend to be harder and transfer more vibration.
As Aye Roll mentioned, the lumpy idle is the nature of beast. I could never get my 90 to idle smoothly. There is only so much you can do..:)
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This should cover it all.http://www.brickboard.com/RWD/volvo/953480/740/760/780/stuff_run_intake.html
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Hi Mike, I am also working on a newly acquired 1990 240, wife's car. We have had it about 1.5 yrs now. I killed the AMM by cleaning it, so I vowed not to ever clean the AMM on this car. I have successfully cleaned other makes' AMMs with improvement in performance.
I remember reading to think about the in-tank fuel pump when the idle is rough and the fuel amount in the tank is getting low. I would not think a dirty sock filter on the in-tank fuel pump could cause a problem but I don't know.
I second the trial of a different AMM but I would try a used part first.
You are ahead of me on the maintenance/repair. I have heard of a smoke test to look for vacuum leaks but don't have knowledge of how to do.
Please post your solution if you figure this out.
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Thanks for the suggestions.
I'll have to check out the in-tank pump. I think it's probably fine because I don't have any issues with power and the car pulls steadily to redline. But it's worth checking for sure.
I may pull the injectors again and send them out to be cleaned. The techron can only do so much. At some point the injectors need to be professionally cleaned/restored.
I've also read the coolant temp sensor (not the one for the gauge, but the one for the ECU) can cause idle issues.
My ICV could be "lazy" which would account for the lumpy idle. Though the RPMs stay steady.
I'll see if I can find another AMM to play with. I'd also like to see if any '93 240s with the LH 2.4 only have 5 pins in the 6-pin AMM connector (AMM has 6 pins while the car's AMM connector harness only has 5 female slots and 1 empty slot). Though I think I'd be seeing a check engine light if my AMM connector harness was damaged, right?
The idle is hard to explain. The engine shake isn't violent, but I think it's shaking more than it should. Almost like an intermittent misfire. I've unplugged each injector, one at a time, and the engine shakes much more violently when I do this.
- Mike
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Adjust the idle up a touch and see if it smooths out.
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Unfortunately you can't adjust the idle on a '93 240. The throttle body doesn't have an adjustment screw like some of the other years (from what I've read).
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This is what worked for me. I did my 93 240 the other week after cleaning the throotle body it was idling too high. There is a small screw through a nut at the front of the throttle body radiator side. Loosen the nut off and with a small flat screw diver from under neath adjust it up or down as needed. Dont break it as its a fine thread.
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Ahhhh, the throttle plate stop screw. I thought you were talking about the idle screw.
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