1989 3800 stalling and hunting at idle - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1987-1991 Parley with regards to your 1987 to 1991 Bonneville, Olds 88 or Buick Le Sabre Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 01-23-2007, 11:27 PM   #1
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Default 1989 3800 stalling and hunting at idle

Hi, this looks like a great site. My 89 leSabre 3.8 is stalling and hunting at idle. I get code 34, but all vacuums and electrics appear OK. The MAF is pretty new, the ICM is fine, the EGR is good, fuel pressure OK. It has new plugs and wires. I suspect the TPS, but have gotten various answers on another forum. I see I can test it with a volt meter and will try to do this. I get no bad code for the TPS, but when I unplug it, the engine idle increases to normal and the car seems to run fine. So I wondered if this unplugging and subsequent running fine is a pretty good indication that the TPS is faulty. I am in Canada so no free tests at Auto Zone or Pep Boys. I can buy a new one, but can the old one be disassembled and cleaned? Also, if not the TPS, what else would you recommend I check?

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Todd
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Old 01-23-2007, 11:30 PM   #2
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Do you have a Service Engine Soon light? I had this same problem once upon a time. It was so bad that the car would basically bog down and stall. It turned out being the MAF sensor. You mentioned that the MAF is somewhat new...it is possible that it is faulty. If you have an SES light, please post the code it is giving.
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Old 01-23-2007, 11:48 PM   #3
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Could have a vacumn leak. or a dirty IAC (idle air control) passage

I'm no gearhead so these are just things I would check when confronted with bad idle and performance issues.
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Old 01-24-2007, 12:39 AM   #4
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Thanks for the replies. I like all help. The code is 34, and the MAF is 1 year old. I am pretty sure it is OK. The car runs great when accelerating, the problem is that it is idling too low, so it hunts and revs up. Sometimes it races, and sometimes it tries, but ghasps and stalls instead. I have checked and changed the vacuum hoses as necessary and I believe there are no vacuum leaks now. I cleaned and tested the IAC.

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Old 01-24-2007, 12:47 AM   #5
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from Techinfo

http://www.bonnevilleclub.com/forum/...e=article&k=68

was there a warranty on that MAF? those things are pricey, had to get one off ebay last summer.
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Old 01-24-2007, 01:23 AM   #6
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haha, yeah i thought so. if its new, it has a warranty, replace it, its faulty. not uncommon, i buy bad sensors all the time. replace that and your car will run a1 again, mine did. same symptoms.


oh and the hunting is called surging. also something mine was doing.
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Old 01-24-2007, 09:03 AM   #7
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Agreed, if you have a code 34 you are having issues with the MAF and the replacements you get are usually totall junk to begin with.. If its under warranty take it back and get another one..

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Old 01-24-2007, 10:54 AM   #8
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The MAF is OEM, and I think it is OK. Code 33 is replace MAF, but I am getting 34. I believe I am getting 34 because the idle is too low and the older GM diagnostics interpret the too low air flow as a vacuum leak. This may be incorrect on my part, but because the replacement is OEM, I trust it. And yes, it cost a whack of cash. I think it was over $600, all because of those stupid little temperature wires burning out. I checked and the warranty is up. The dealer already hates me, so no joy there once outside warranty.
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Old 01-24-2007, 11:04 AM   #9
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$600 for an MAF is Rape... Thats nuts on their part.. That dealership sound like a bunch of Scam artists...

Code 34 is for the MAF..

Yu may trouble shhot the TPS, but if you were having the issues you are right now you would usually have a Code 22 or possibly 21... IIRC there is no code 33 for the 88-91 Vin C engines..

You aslmost need a scantool to check the readings the ECM is getting from the various sensors..

Once your idle does come down a little, unplug the MAF( try to keep it running ) and see if it will idle, most will idle without the MAF once its feathered back to idle, if it idles smooth you'll know what the problem is... If it does the same and tries to idle all over the map as usuall, than you may need to test the TPS for dead spots or irrability... If thats the case the TPS will need to be replaced.. Both the MAF and TPS can cause a lot of issues... Usually tho if its one of those 2 items, its a 34 for the MAF and 22 for the TPS... But do check and see what you find

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Old 01-24-2007, 11:34 AM   #10
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Thanks very much.

That is a lot of great info.

Todd
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