rough idle/surging after start...stumbles when driving - 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 12-08-2004, 11:08 PM   #11
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jr's3800 AKA Admistratorman,

You hit the codes dead on. I had them pulled by Advanced Auto Parts using a Actron CP9145 scan tool. They took it inside and hooked it to a printer and gave me a printout. I don't know why the code # are different than you wrote but the definitions seem to match. It reads as follows:

P0101......Mass Air Flow (MAF) Sensor Signal Failure

One of these was listed as a current code and the other was listed as a history code. When do these codes go from current to history? After one or two key cycles?

P0171......Fuel Trim Sensor Signal Lean

P0571......ABS Traction Control PWM Signal Problem


I was not to concerned with this one right now. The car has had a traction light on since she has owned the car although the ABS seems to be fine.

P0626......VATS Failure

P0629......Pass Key Frequency Invalid


I have not concerned myself with these two either because the car does crank and start. To answer your question, the security light works normal. It flashes during key on engine off and shut off shortly after the car starts. It never comes on while driving once it has gone off after starting.

The last two days the car has been happy. It has not missed a beat or thrown a code since I lasted posted that it threw a code. (another P0101) The engine has not misfired and everything seemed good. I have not replaced plugs and wires yet. I did a close visual inspection of vacuum lines and they appear to be good.

Tonight I started the car and it misfired again. It started running like a pos and continued to misfire. It has thrown several codes (no doupt they will be P0101s) Then out of the blue it starts running right again.

I believe that plugs, wires and vacuum leaks can and will cause drivability/performance problems. What gets me is that when it runs right, which was two days in a row most recently, it runs perfect. No rough idle, no stummbling at highway speeds and good acceleration. Does this sound like any of those things could be the problem? The problem seems to be intermitent and there is nothing I can attribite it to.

I appreciate you guys hanging with me on this. This forum really is a great resource. I posted on another forum that was all makes, all models and didn't get any responses.

Thanks Again,
Rob
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Old 12-09-2004, 12:58 AM   #12
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Quote:
Originally Posted by jr's3800
I would like to have a scantool hooked up to the car to see what the MAF is up to or if there are any intermintent drop outs from the MAF
What scan tool do most of the guys around here like? I have a laptop computer. Are there any PC based setups that are recomended? I am thinking something that leaves an audit trail would be ideal. I could leave it hooked up to the car and review it every day.

Quote:
Originally Posted by jr's3800
I would hate to have you replace the PCM and have that not be the actuall problem..
What is the cost of a PCM? Where is the best place to buy one?

Quote:
Originally Posted by jr's3800
I say this a lot... I'f I lived closer we'd have some parts to throw at it...
I know a guy who has a wrecked 95 ssei just exactly like my g'friends. He is putting the engine and trans in a small Mitsubishi car he'* building to drag race. Maybe I could talk him out of his PCM for a week and see what happens.

Sorry about the questions. I'm sure I could find the answers by using the search function. I'm just a little short of time to do so right now.

Regards,
Rob
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Old 12-10-2004, 08:46 PM   #13
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I put a reman'd PCM in the car yesterday. (cardone from Autozone...$89.95) The car ran good yesterday and today, then threw another code this evening. I am out of town so the g'friend will have the code pulled tomorrow.

She is going to ring out the MAF wires and ohm them out and see if she can come up with anything more. I was hoping someone could provide me with the pinout for the MAF at the PCM. Otherwise she is a EE and is quite capable. Just hoped to save her some time.

Were going to keep plugging away at this thing until we find the problem.

I still could use some scan tool and/or computer program info also.

Thanks All,
Rob
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Old 12-11-2004, 09:54 AM   #14
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Come on, Someone with a 95 FSM get this guy some pinouts....
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Old 12-11-2004, 03:59 PM   #15
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Quote:
Originally Posted by jr's3800
Quote:
Originally Posted by Damemorder
Come on, Someone with a 95 FSM get this guy some pinouts....
Workin on it...
Thanks jr's3800!!!!!

I just got off the phone with my g'friend. She had it scanned again and it is still throwing P0101 (MAF) I forwarded her the pin outs and she is going to jump in there with a meter. I suggested that besides checking wires going to MAF that she looks at computer grounds. Is there anything else anyone can think of? Has anyone ever had a problem with the connectors? They seemed to be fairly well built but I know connections in wiring is always a likely place for failure.

Thanks again guys!!! Y'all Rock!!!
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Old 12-11-2004, 04:26 PM   #16
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The PCM grounds are on the engine, Just below the coil packs. And there'* one below the dash on the passenger side A-pillar, Just pull the carpet back.

Good luck man!
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