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'98 T5M Idle and Power Issues

Help, Advice and DIY Tutorials on Volvo's P80 platform cars -- Volvo's 1990s "bread and butter" cars -- powered by the ubiquitous and durable Volvo inline 5-cylinder engine.

1992 - 1997 850, including 850 R, 850 T-5R, 850 T-5, 850 GLT
1997 - 2000 S70, S70 AWD
1997 - 2000 V70, V70 AWD
1997 - 2000 V70-XC
1997 - 2004 C70

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echase76
Posts: 105
Joined: 6 December 2011
Year and Model: 1998 v70 T5m
Location: State College, PA

Re: '98 T5M Idle and Power Issues

Post by echase76 »

Pulled the FPR last night and cracked it open. Solder looked pretty good, but ordered up a new one anyway as the caps might be bad. If that is not the issue it will be one someday, so better to have a spare.

Used about a can of carb cleaner around all the lines and found nothing. Still think I have a small leak somewhere.
Recleaned the IAC just in case. Pulled the ECU and cleaned the pins.

Ran great this morning (very cold weather), but my issue is intermittent enough that one 15 min drive does not tell me too much. Need to get through a couple drive cycles.
1998 V70 T5m Silver/Charcoal - 150K

jblackburn
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Joined: 8 June 2008
Year and Model: 1998 S70 T5
Location: Alexandria, VA
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Post by jblackburn »

Ran great this morning (very cold weather), but my issue is intermittent enough that one 15 min drive does not tell me too much. Need to get through a couple drive cycles.
Cleaned the MAF last night. Definitely dirty, had some black buildup on the leading edge of the sensor. Ran really well after the cleaning and idle was rock solid after the computer relearned. Continued to run strong today without any issues. I suspect that the dirty MAF was the main culprit.
If a vacuum leak was the problem, it would be consistent.

I'm inclined to think that the mass airflow sensor may be giving flaky readings at times.
'98 S70 T5
2016 Chevy Cruze Premier


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echase76
Posts: 105
Joined: 6 December 2011
Year and Model: 1998 v70 T5m
Location: State College, PA

Post by echase76 »

Thanks for the thoughts. This is definitely not a consistent issue.

I have a used but working MAF paid for, but the seller is being VERY slow delivering. FPR will be here Wednesday.
1998 V70 T5m Silver/Charcoal - 150K

echase76
Posts: 105
Joined: 6 December 2011
Year and Model: 1998 v70 T5m
Location: State College, PA

Post by echase76 »

Ok folks it looks like I can close the book on my issues. Turned out the be the MAF going south (jBlackburn you were right!). Didn't seem like the classic MAF symptoms, but that is what did the trick after trying everything else. For the past week I have had no issues and runs strong.

Thanks for all the help and ideas!
1998 V70 T5m Silver/Charcoal - 150K

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