Stumbling '89 Olds 88

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  #1  
Old 11-15-02, 06:42 PM
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Unhappy Stumbling '89 Olds 88

Please help! My wife's '89 Olds 88 has a maddening stumble and occasional stall when warm. This car has the 3.8l Buick v-6, port fuel injection and the ubiquitous 4-speed automatic(overdrive) transaxle. The stumble is faint but noticable at steady speed, city or highway. It gets more pronounced under acceleration. The engine has stalled a couple of times that I know of; once while standing idle at a stoplight, and once while coasting to a stop while approaching a stoplight. The only code I can get the computer to cough up is a 65. My Haynes manual says this could be a cruise servo position sensor problem; it also says this is the same as a code 63, which points to an EGR flow check problem. Since the stumble is constant, and not only when the cruise is engaged, I'm ruling out the cruise servo position thing as the cause of the driveability problem. So, how do I go about checking that the EGR valve(looks to be electrically actuated) is opening/closing and flowing properly? And/or is there another area I need to explore? Additionally, when I recently changed the trans filter and fluid, I found two thin, crescent-shaped pieces of what looked like aged white plastic/nylon, could have been pieces of the same part or duplicate parts. First, what could they have been? And second, could this mean my trans is on borrowed time? Any input would be greatly appreciated! thanks - Chris
 
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  #2  
Old 11-15-02, 08:28 PM
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the plastic pieces found in transmission pan is not a good sign and you are likely on limited time with the transmission it is likely a washer that is used to take up excessive clearances.
as far as the stumble you might start with a tune up and new set of plug wires if hasnt been done recently, also check the mass air flow sensor either screwed on at the throttle body or inline at the air intake hose tap on it lightly with the engine running see if the car dies are changes rpm is a good indication it needs replaced, if it has the maf sensor that has 3 screws holding it on at the throttle body you can remove it and clean with carb cleaner the 2 wire elements that get coated with buildup and reduces the maf efficiency thus causing your engine to run lean.
if it has the maf sensor that hose clamps into the air intake hose it cannot be cleaned and should just be replaced if found to be bad by tap testing.
start there and see if it doesnt take care of the stumbling.
 
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Old 11-16-02, 06:01 AM
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I agree with BeJay. Good advice...
 
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Old 11-16-02, 11:43 AM
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bejay and Joe_F - Thanks for the input. I've read before in this forum that the same problem could be caused by the EGR valve being carbon-laden and not functioning properly as a result. I've also seen you guys diagnose based on the interaction between the various sensors and components. That's finally starting to make sense to me, thanks to your help. So, I'm off to find the MAF sensor and check the wires for crud buildup. I'll let you know what I find. Thanks again - Chris
 
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Old 11-16-02, 01:47 PM
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Yep - if what I took off was the MAF sensor(three screws holding small black plactic/aluminum rectangular piece in a casting upstream of the throttle body), the two wires were pretty cruddy. A shot or two of carb cleaner and a follow-up with electric contact cleaner cleaned 'em up pretty good. The throttle plate is still pretty gunked up - can it be cleaned in the same manner? Also, can someone tell me what the little 3-wire appendage at about the 5-o'clock position (looking into the throttle body) is? Maybe the connection for the idle speed motor? And is the little sensor in the bottom of the air cleaner the air temp sensor? Just curious... Once I get the brakes repaired and the car back on the road, I'll update this post as to results of the cleaning. Thanks for help - Chris
 
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Old 11-16-02, 04:10 PM
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You're probably talking about the idle air control valve and the air cleaner temperature sensor. Check autolibrary.org in my signature file to learn more about these items.

You should be able to clean the throttle body with some WD40 or other cleaner. Clean the hot wire on the MAF CAREFULLY with some electronics spray to avoid damage.
 
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Old 11-16-02, 05:35 PM
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Once again, thanks! I started the Olds after reinstalling the cleaned MAF sensor, but since the brakes are still out of service, I did not drive it. However, the car started up instantly (I had not noticed how long it was taking before), and the stumble upon shifting into gear with the engine still cold was gone! I can't wait to get it back on the road to see the rest of the results. Meanwhile, I will try to clean the throttle body as you suggest. More later - Chris
 
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Old 11-16-02, 07:03 PM
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You can get special Throttle Body cleaner at the auto parts store. Follow the directions on the spray can. If you are having EGR concerns than you must check the complete EGR circuit...that includes the EGR valve, vacuum lines and any solenoids that are in the circuit. Also clean the ports under the EGR valve that lead to the intake manifold, they get plugged also. Might be time for a new one?
 
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Old 11-16-02, 08:51 PM
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Thanks, Stevo. I was wondering, after the MAF sensor cleaning went so well, if I still needed to chase the EGR thing. I suppose that and the throttle body cleaning couldn't hurt, and certainly may help. I was not aware of the availability of special throttle body cleaner; I'll have to check it out. Thanks again. More as time and money permit - Chris
 
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