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240 Bogging Down During Cold Starts

B

BuddeTheBlueBrick

New member
Joined
Jun 14, 2020
So this has been bothering me for over a year now. It seems to go away when the weather is over 40-50F. Today it was 30F after a week of 60+ so I decided to see if it would happen again since it ran well all week. Though I did have the battery unplugged because I wanted to measure the coolant temperature sensor at the computer plug, so that may affect some things. it was 6.3k ohms so I think that's within spec.

https://streamable.com/y6t00q

As you can see it runs choppy until about 22 seconds in, and then it just bogs down. It has never died on me but it feels like it wants to. Sometimes the check engine light will come on if it gets really bad, but it doesn't seem to leave any other code other than 2-3-1 or 2-3-2, which it has whether the light is on or not. That code doesn't seem to give me much to go on. At the end you can see the tailpipe is puffing a little bit of black smoke, so it's definitely running rich, and my gas mileage has suffered this winter. It's been like 14 when I usually get 20ish. The car runs pretty okay outside of idling, but when I get to where I'm going and put it into park, the idle spikes up pretty high like I'm giving it gas to the point the car shudders when I shut it off. On the very rare occasion, and I don't know if it's related, but it can hesitate pulling away from stop signs and has almost died in the middle of an intersection more than once.

Anyway, since it seems so related to temperature I thought maybe the CTS would be the culprit, but the resistance test tells me otherwise. Plus I've replaced it once before last year hoping it would solve the issue. I thought it did, but it might've just been the warmer weather since I did it at the end of April. I've run the DTM 3 and the IAC clicks on and off and the injectors work. The pumps work, I can hear them. The oxygen sensor works from what I can tell and it's 2 years old, plus from my understanding it doesn't take effect until the car has warmed up a little. I've cleaned and tightened grounds, there's no air leaks that I can find, and since the car runs fine warm I wouldn't think those would go away because of that. The FPR is also new, I had a spare, as well as a new fuel filter. My only guess is the MAF, but does that care about temperature? I've done the ohm test on it but I've heard that wasn't reliable at all.

Any thoughts are appreciated, thank you!
 
What year and what fuel injection? Did you measure the coolant temp sensor at three operation points? You are supposed to measure cold, then warm, then again fully up to temp. You can check out the cleanflametrap.com website for a lot of information to help troubleshoot the maf.

Bogging only when cold can be a vacuum leak. Carefully check over the intake hose between the throttle body and the maf. Take it off to check the bottom. Check all the small vacuum hoses for cracks and split areas. LH 2.2 make sure the vacuum hose to the icu is in good shape and clear.

Edit:I see it's LH2.4. Seems like it is way too rich. Be sure to check the plugs and make sure the gap is correct. Make sure the ignition isn't shorting out to anything. Be sure the top of the coil is clean and no spark leaking.
 
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dl242gt said:
What year and what fuel injection? Did you measure the coolant temp sensor at three operation points? You are supposed to measure cold, then warm, then again fully up to temp. You can check out the cleanflametrap.com website for a lot of information to help troubleshoot the maf.

Bogging only when cold can be a vacuum leak. Carefully check over the intake hose between the throttle body and the maf. Take it off to check the bottom. Check all the small vacuum hoses for cracks and split areas. LH 2.2 make sure the vacuum hose to the icu is in good shape and clear.

Edit:I see it's LH2.4. Seems like it is way too rich. Be sure to check the plugs and make sure the gap is correct. Make sure the ignition isn't shorting out to anything. Be sure the top of the coil is clean and no spark leaking.
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It's a 1990 and LH2.4, sorry. I've only checked cold recently but warm and hot were in spec last time I checked and it was still doing this. But I can check again next chance I get. Can vacuum leaks go away when the ambient temperature is warmer? I've checked the intake hose before and there's a couple thin spots, but no real holes yet that was passing air through. I put some glue on it to be safe. I may replace the hose too if the MAF is the culprit though. My other hoses are in good shape and the intake gasket is new last year. The spark plugs and wires were done new last year too and the gaps were fine then. This was all after the bogging started too
 
So another mid-30s day and another day of running like crap. When I got home I measured the CTS again with it warmed up to temp and it was 289 ohms, so again within spec. It idles better if you restart it after it's warmed up though. Still a little higher than normal but it doesn't bog down. We'll see how it acts in the next few days. I think it's supposed to warm up a little again.
 
BuddeTheBlueBrick said:
So another mid-30s day and another day of running like crap. When I got home I measured the CTS again with it warmed up to temp and it was 289 ohms, so again within spec. It idles better if you restart it after it's warmed up though. Still a little higher than normal but it doesn't bog down. We'll see how it acts in the next few days. I think it's supposed to warm up a little again.
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I ended up using the above said website to find out my Maf was bad replaced it and had to replace the 1 year old 02 sensor at the same time. I was having the exact same issues. Black smoke, rough starting and car would almost stall after initial depression of my pedal then it would pick up and take off.This fixed it after much research but this was only my experience.
 
Well it still ran the same at 55F today, but ran a little better tonight while it was a tad cooler out. No high idle on park, anyway.

Dvroofer said:
I ended up using the above said website to find out my Maf was bad replaced it and had to replace the 1 year old 02 sensor at the same time. I was having the exact same issues. Black smoke, rough starting and car would almost stall after initial depression of my pedal then it would pick up and take off.This fixed it after much research but this was only my experience.
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Do you happen to remember the link on the site? I can't find anything MAF related on cleanflametrap but maybe I'm not looking properly.

dl242gt said:
When It's acting up. It may help to check the fuel pressure.
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I'd love to but I don't have anything to check it with unfortunately
 
Ran a little choppy today still. Better than the other day though. I unplugged the MAF and started it and it barely ran much worse. I got the 1-2-1 code and check engine light for missing MAF signal though. I may just pick up a used MAF off ebay and hope it works, and if it doesn't I hear it's good to have a spare one.

dl242gt said:
You can use this adapter to connect into the fuel line. It lets you use a generic fuel pressure kit to test your car. https://www.toolsource.com/volvo-to...njection-adapter-14mm-lhjetronic-p-55212.html.

One of the times I've experienced this type of behavior it was an intermittent fuel pump. The pump would only make just enough pressure to let the car run but not accelerate well.
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Thank you. If an MAF doesn't fix it I'll go this route. But wouldn't it have enough pressure if it was running rich because too much fuel?
 
Just one more quick thing. Seems like temperature doesn't have much to do with it. 70F and still running poorly. Bogged down and then the idle got higher as I let it sit until it was too high, and I know I'm not supposed to but I unplugged the MAF while it was running and the idle went back down to acceptable levels. Does this mean the MAF is bad? Still runs bad when started with or without the MAF
 
Try clearing out the codes and see if that helps. If it has enough fuel pressure then it could run rich and run poorly. My friend tried out one of the $30 maf sensors from ebay and it actually runs good in the car. Don't know how long it'll last.... His Car was running like crap, was tough to start and was missing and popping once it did start. Disconnected the maf and it started running smooth. Cheapo ebay maf cured it. lol.
 
Inspect the terminals for corrosion. Peel back the MAF connector boot and make sure the crimps aren't corroded either. Inspect the ECM connectors for damaged terminals too.
 
dl242gt said:
Try clearing out the codes and see if that helps. If it has enough fuel pressure then it could run rich and run poorly. My friend tried out one of the $30 maf sensors from ebay and it actually runs good in the car. Don't know how long it'll last.... His Car was running like crap, was tough to start and was missing and popping once it did start. Disconnected the maf and it started running smooth. Cheapo ebay maf cured it. lol.
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I was leaning that route and hoping for the best. My current MAF is a reman injection labs one. No idea how long ago it was done but maybe it's just too tired now.

ZVOLV said:
Inspect the terminals for corrosion. Peel back the MAF connector boot and make sure the crimps aren't corroded either. Inspect the ECM connectors for damaged terminals too.
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I've done that and they're all clear. Even cleaning the MAF with MAF cleaner didn't help.

I'll pick up an ebay MAF and report back whenever I'm sure the results are clear. In the mean time, thanks everyone for help :run:
 
I have a stash of several MAFs. If you need a used OEM one PM me. It would be a known good unit tested on my car.
 
Just a quick update. It's been just over a week since I put in a "new, old" MAF and it's running much better. Tested in both cold and warm weather. No more trash idling and though I haven't verified at the pump yet my gas gauge seems to be dropping slower. Acceleration feels a little tighter too and start up is smoother.

Here's hoping I didn't just jinx it :x: Thanks everyone
 
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