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Old 08-09-2005, 07:58 AM   #1
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I've been having problems with a 1995 SE.

First noticed a few problems going uphill--like the transmission wasn't engaging smoothly, but definitely no tranny problems. Quickly deteriorated to rough idle, surging in idle, stalling and CEL. The code pulled is P0101--MAF Sensor. Replaced it, a foul IAC and PCV. Throttle body clean. Checked vacuum hoses and replaced leaky connectors to cannister. Fuel pressure at Schrader about 40 to 48 psi--will read that even as it dies during a poor idle.

Car runs fine when hot, with only intermittent surging/stalling, particularly at traffic lights where I do the brake/gas thing to keep it going at times. Occasionally the car runs beautifully from start to end-of-ride. Starts fine about half the time. Starts and runs best if left in the hot sun. Problems are worse during the evening.

P0101 is the only code I get, but the CEL does turn off sometimes when the car has had a good ride.

What could cause a MAF Sensor code other than the MAF itself, MAF cable, bad battery connections or PCM issues?
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Old 08-09-2005, 10:14 AM   #2
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Does it start fine when its cold and start to sputter after its warmed up some? Could be your cat convertor?
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Old 08-09-2005, 10:57 AM   #3
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Quote:
Originally Posted by PontiacDad
Does it start fine when its cold and start to sputter after its warmed up some?
No, sometimes its very hard to start from cold. Yesterday, for example, it sputtered when I started it up first thing at noon--seemed to misfire a bit for the first couple hundred feet--had to give it plenty of gas'n'brake. Straightened out right after that and drove reasonably well although idled rough for much of the day. Parked it at 1:30 and started it easily at 4:00 p.m. idling and running almost perfect. Home at 5:30. Out again at 6:30 p.m.--surging and stalling during idle.

Sometimes when it establishes a bad idle that doesn't cause a stall, its quite rhythmic, racing and slowing down in a set pattern. I took the fuel pressure during one of those and that'* where i got readings fluctuating from 41 to 47 psi. Idle RPMs fluctuate back and forth from about 800 to 1200, then settle at 1000.
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Old 08-09-2005, 12:16 PM   #4
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Shot in the dark here, but my family has a '95 Olds Eighty-Eight that had some similar problems. Our mechanic went round after round with that thing but couldn't track down the problem. He finally figured out that the PCM was throwing "fake" codes because it was on the fritz. He threw a good unit in there and the car was fine.

I don't think a PCM is the first place you should look, but if it'* giving you a code and you've replaced the corresponding part to no avail, you may want to consider getting a junkyard unit.
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Old 08-09-2005, 12:37 PM   #5
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Make sure you MAF wires are well away from the spark plug wires. I was having a MAF problem couple of years ago, replaced the MAF but the problem was still coming back. I hung the MAF wires with a tie wrap away from spark plug and the problem seemed to go away.
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Old 08-09-2005, 01:13 PM   #6
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Thanks. I'll start with the MAF wires then see if I can find a junkyard ECM.

I read a huge number of posts here before posting myself, and I haven't seen one where the scanner consistently read only that single P0101 code. Most of the really complicated situations seemed to have the scanner throwing 4 or 5 different codes.

Assuming the ECM is still functioning, is it logical to conclude that if the problerm was in theO2 sensor or some other sensor that the ECM would choose a code for that particular sensor, rather than referring the problerm up or down the line?
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Old 08-09-2005, 06:34 PM   #7
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I checked the MAF electrical lines and they're properly routed.

One thing I noticed. When I was parked and the engine was idling nicely I turned the AC on full. The engine began to idle roughly and surge--slowly at first, then faster and faster until the engine found its new idlle under the AC load.

When I turned off the AC in a good idle, the engine also surged and ran roughly, but the surges were much slower and the engine found a proper idle much more quickly.

Does that sort of behavior lead to any conclusions?
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Old 08-10-2005, 12:03 AM   #8
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I had the same problem for months ..I practically changed everything from the ignition module to the ECm to egr crankshaft sensors,plugs wires....nothing helped....by luck when I changed the Maf sensor...the new one threw a code...so when we checked it was the 12 volt on the sensor itself that was not making good contact...i cleaned it...bend it a bit and tied the whole bundle with a tie rap away from the egr hot tube that it was resting on...no more problem....

Check with a low voltage tester the voltage on you maf wires and also the ground....
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Old 08-10-2005, 09:08 PM   #9
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We first need to know what all of the codes are...

Next like it has been said, you will want to check the grounds..

You will also want to make sure the Alt is putting out 13-14v... Anything lower than 12.6 is a bit too low... Understand that a low period that lasts a few seconds is normal..


You car sounds flakey, I'm wondering about the PCM as I have bee through 2 in my 95... The OBD 1.5 stuff was very interesting... But the PCM lasted as long as the old ECM'*...

Check everything first before suspecting the PCM...

Once you have managed to check everything, and if you still have the same issues, make sure your stereo( if original ) is not in Theftloc mode... Disconnect the battery and allow a few minutes for the computer loose its memory... Reconnect and see if the codes return when you turn the ignition on( do not start the car )...

If you have a scantool or a friend with a scantool you can simply erase the codes with the tool.. Cycle the ignition off and start over, this time turning the ignition on( engine off ) and see if the codes return...

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Old 10-29-2005, 01:14 AM   #10
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Didn't want to be the type of user who posts the beginning and not the end of a sordid Bonneville adventure. Here'* how the MAF code story ends. I decided to try to learn as much as I could about the car on my own without resorting to a mechanic, or bothering people here with inane questions without brushing up my own knowledge first. I checked fuel pressure, I fixed vacuum leaks--and there were a couple of them. Problems seemed to come and go with the rough idle, but mostly come.

After checking the MAF connections, I decided that the MAF code was plain incorrect. Since the most obvious sign of trouble was the wild fluctuations in the alternator, I thought I'd replace that next--my logic being that wildly fluctuating voltage would cause the ECM to misbehave, or at least mess with all of the other electrical systems.

Bought a remanufactured alternator, installed it, started the car and--HEARD A LOUD CLANKING NOISE FROM UNDER THE CAR! MY harmonic balancer had chosen just that moment to separate. I didn't have the tools to handle it, so I had it towed to a nearby garage. They fixed the balancer and the crankshaft position sensor.

AHA! I say to myself, "the CPS!" Somebody else on the board had a CPS cause just the same problems as I had. When the garage tried to start up the car--NOTHING happened. The car cranked, but no start. After far too long, the mechanic discovered the car was receiving no fuel to the injectors. The SCAN tool threw codes relating to bad keys and an anti-theft module I'd never even knew existed.

The car was hauled to an electrical specialist who replaced--YES--the ECM.

My advice to anyone--buy an inexpensive, used ECM for $50 before you need it. If you experience weird problems that defy logic, start with that and then work your way up through the more expensive repairs.
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