Terrible Rough Idle, Good MPG = *BLOWN SC gasket*..pics pg 2 - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 03-05-2007, 10:36 PM   #11
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could this possibly be something related to a faulty cam sensor but not throwing a code? I'd think if that was the case I'd have a screwed up idle at 1200+ too.

I'm guessing MAF or IAC...to start. If those are swapable between a 2000GTP i can swap in my garage and test. if I recall the 98'* maf sensor was different.

maybe even a failing EGRvalve that has not gotten to the point of throwing a code?

what else would be just at the low RPMs? it does not sound like a misfire at all, it is just "lumpy" to try to desribe it..I can get a video.

I dont like throwing parts to guess but I'm having a hard time finding a similar case on the SEARCH here.

Its dropping about 200 rpms 2 times a second...just shakes kinda but is smooth while it does it.
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Old 03-05-2007, 10:49 PM   #12
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Did you clean the maf? Follow the other stuff already mentioned?
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Old 03-06-2007, 01:12 AM   #13
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Please stop editing the topic title so we know it'* the same topic.

Have you done anything suggested yet? No sense asking more questions until you do.
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Old 03-06-2007, 02:03 AM   #14
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Quote:
Originally Posted by willwren
Please stop editing the topic title so we know it'* the same topic.

Have you done anything suggested yet? No sense asking more questions until you do.
The topic was not very clear and I did not want others to read the title and get confused, I've cleared it up.


Yes the MAF and IAC has been cleaned.
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Old 03-06-2007, 08:29 AM   #15
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Ok..you checked the maf and IAC, done most of the tune up and it'* still acting like a vacuum leak. Give this a try.

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Spuds...after reading your ride post on the new car. I'll have to suggest that in fixing up all the leaks and issues. You may come across the problem or at least be able to rule out many items.
Also.. remove the coils and test the primaries as well as the secondaries (I believe you've tested the seconardies already?)
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Old 03-06-2007, 09:06 AM   #16
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Then you should have SAID that you did that.

Plugs and wires were replaced 'awhile back'. Pull them and check them. Did you clean the IAC passage in the TB and clean the TB itself? Check the coils as suggested. These are all the 'normal' things you do on high-mileage cars.
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Old 03-06-2007, 04:18 PM   #17
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First thing I do with any new car is clean the throttle body and clean the TB sensors regardless of age or miles. This was the first thing I did, I then changed the plugs, and wires, this was done on Sunday.

The TB was amazingly clean for the age and miles, It was much cleaner than my 93 was.

next step is to check the primarys, I will do this and check back.

I also hope to get my hands on a IAC and MAF sensor, and swap on. I'll do the other troubleshooting first though.
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Old 03-06-2007, 04:19 PM   #18
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did you get my pm, will that maf work for you?
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Old 03-06-2007, 04:20 PM   #19
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Quote:
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did you get my pm, will that maf work for you?
yes i did, I need to get off my lazy but and verify the numbers are the same.
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Old 03-06-2007, 09:46 PM   #20
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number afh50m-04 is the one..stay on your lazy butt
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