240 92 244 idle problem after warming up

93 244 idle problem after warming up

About 4 minutes after starting 93 244 2.4 starts to idle like this: See attached youtube video.


She has been to two different mechanics, both claiming to be Volvo specialists, over the past month.

1st mechanic "who said he fixed it" said that there was a ground problem with a wire, that's why I had the volt meter on it. I was seeing if there was a drop off before the idle problem. Doesn't seem to be the problem. I was getting 13.78 volts and it only starts dropping after it starts to stall.

The idle issue will get progressively worse until it stalls completely if left alone.

Any thoughts on where I should start. I've tried known good MAFs, Idle Air Valve, and Fuel pump relays.





https://youtu.be/GhplZIh0EH8

Looking under your hood, I'd say this car has some history. Is the history yours or did you just get this car with this problem? IOW, how did this come about?

If I were the mechanic you brought it to, I'd ask the above question before checking the fuel pressure and air filter. Then, if normal, I'd be monitoring the voltage at pin 2 of the ECU, which I'd expect to be a -951. I'd want to make sure it was close to ground every time I took my foot (or left hand) off of the accelerator pedal, checking the action of the throttle position switch's idle contact.

While at the ECU, I'd probe the temperature sensor voltage at pin 13 if my nose didn't tell me it was way rich. Maybe even the oxygen sensor at pin 24.

Then if all that was normal, I'd move my testing to the idle valve (pin 33) using a meter measuring duty cycle (like a dwell meter) or my scope, to see if the idle drops corresponded to extremes of valve position near 25% at the bottom end or 63% at the top end of its control.

I'd be thinking the answer would likely lie in "what was done last." I hope it is just a dirty or misadjusted TPS combined with a throttle plate in need of attention. Only very reluctantly, would I replace parts to diagnose it, such as the ECU in addition to the AMM, which I'm guessing you've already tried.

Pretty hard to second-guess one, let alone two, professionals.

The history is that I have been restoring this thing for the last two years. It was bought with 200,000 on it, but seemed to have been well cared for, I started with the cosmetics because I wanted my teenager daughter (17 at the time) to see the possibilities. She got cancer right after we got started (Hodgkin's lymphoma)... so the project was on hold. She has been cancer free for over a year now and I am trying to get this thing finished for her.

There isn't much that I haven't done during that time. I didn't pull the engine because everything seemed to be working fine and no leaks. Things that I did do to the engine included:

New hoses all around
New PCV parts and hoses
Re-did intake manifold - sanded out the rust, cleaned, painted, and new gasket
Re-did the exhaust manifold w/new gasket
New exhaust downpipe (actually all the exhaust, minus the cat converter section is new)
Removed all the throttle stuff and cleaned
Renewed the injectors
New plugs, wires, belts,
Had the cylinder head shaved (very little) and cleaned. New head gasket and bolts
New timing belt, and seals
Only thing I didn't do was the oil pan gasket and rear main


I had some problems with blown fuse on that battery terminal mounted fuse box and running rough when I finished. After I worked those things out, It started really blowing oil out the the front near the oil pan. I had advice that sometimes there could be a clog in the oil drain because there shouldn't be pressure there. I thought I was over my head and took it to the mechanic. He kept the thing 4 months! I did have him do some other things like flushing the brake system, cooling system, and tapping a water pump bolt, but he kept telling me that he was having some difficulty pinning down the leak, and then solving the idle issue. He's a Volvo specialist who has owned more than one 240 and he had done good work in the past for me.

When I got it back it was running o.k. at first. It had a problem with a loose exciter wire on the alternator, and then the oil leak returned and the idle issue in the video.

Oil appeared to be coming out of the oil pressure sender and possible the front main seal. On Sunday, after I made the video, I pulled the timing belt and put in a new front crankshaft seal, intermediate seal, and the sender. I also pulled the timing cover and put in a new gasket. Finished it today. After this new work, there was no leak and it wasn't having the idle problem during a brief test.

I then drove it about 10 miles and it started blowing oil everywhere. This time it appears to be from the head gasket area, maybe the valve cover, I can't be sure yet.

Could there be something other than the pcv system causing oil pressure issues? I would have thought that the mechanics did an oil pressure test and ruled out a problem. I will ask them tomorrow.

I am so lost at this point. I have done so much to it and now I am not sure I can even trust either of the mechanics. I have hundreds of hours in on this thing and I can't seem to get it working at this point.

Where did you get that blue head cover? Is it painted?

This thread was started new again as "what would happened with a reversed emissions control valve."

I think that I may have solved the problem..... I'll have to redo the camshaft seal to be certain, but it seems to run better now. I know it will take some time to re-learn. I don't see how it even ran before.

VolvoLatAm said:

Where did you get that blue head cover? Is it painted?

Click to expand...

I powder coated it. Swedish blue and yellow for some of the parts

cleanflametrap said:

Looking under your hood, I'd say this car has some history. Is the history yours or did you just get this car with this problem? IOW, how did this come about?

If I were the mechanic you brought it to, I'd ask the above question before checking the fuel pressure and air filter. Then, if normal, I'd be monitoring the voltage at pin 2 of the ECU, which I'd expect to be a -951. I'd want to make sure it was close to ground every time I took my foot (or left hand) off of the accelerator pedal, checking the action of the throttle position switch's idle contact.

While at the ECU, I'd probe the temperature sensor voltage at pin 13 if my nose didn't tell me it was way rich. Maybe even the oxygen sensor at pin 24.

Then if all that was normal, I'd move my testing to the idle valve (pin 33) using a meter measuring duty cycle (like a dwell meter) or my scope, to see if the idle drops corresponded to extremes of valve position near 25% at the bottom end or 63% at the top end of its control.

I'd be thinking the answer would likely lie in "what was done last." I hope it is just a dirty or misadjusted TPS combined with a throttle plate in need of attention. Only very reluctantly, would I replace parts to diagnose it, such as the ECU in addition to the AMM, which I'm guessing you've already tried.

Pretty hard to second-guess one, let alone two, professionals.

Click to expand...

Big Thanks Art!


Problem Solved. After also fixing the leak at the exhaust manifold to downpipe. I started the fault tracing from the LH 2.4 greenbook. You were right, it was the throttle position sensor. It showed like .7 ohms and not anything like it should with the pedal depressed. Thanks again.

I swapped in another one i had, and its running great.