1991 Oldsmobile



October, 15, 2007 AT 11:08 AM

I have a 1991 Olds Ciera 3.3L with 125k miles that has been giving me a few problems since it was purchased.

Sometimes when coming to a stop the car idles up high then when applying the gas pedal the car will sometimes either hesitate or stall completely. Upon restarting oftentimes a small puff of black smoke emerges from the exhaust. I also have higher fuel consumption then I should have. At first I was told by a mechanic that I had a clogged converter. He drilled several holes into it and told me if it helped that I would need to have it replaced that it was indeed clogged. All that has done for me is make the car much louder but driving problems have remained the same, so I guess converter wasn't clogged.

He then told me clogged Fuel Filter which I purchased and changed, did nothing to help.

He then cleaned the contacts on the Mass Airflow Sensor and pointed out that my air filter AND the screen on the Mass Airflow sensor were both black from carbon. He told me that when he cleaned the contact on the sensor that it fixed it, so I bought a new air filter and put it in as well. Within a week the new air filter was blackened again from carbon. Then based on the below-posted Check Engine Codes I retrieved with my Check Engine Light I purchased and installed an Engine Coolant Temperature Sensor, Oxygen Sensor, and Throttle Position Sensor, NONE of which helped anything at all. In fact, the Check Engine Light still spits out those same codes even after those were all changed. The guy then tells me my computer is bad in the car and that it is THINKING that those things are bad and then compensating/adjusting the car's mixture to attempt to correct the problems that it " falsely" sees.

After taking the car elsewhere for a second opinion I was told that was unlikely. They said to change the PCV valve and then if that didn't fix it to change the Mass Airflow Sensor. I bought a PCV valve but I nor anyone I have taken the car to can find it on this car. I finally uncovered via the internet that to change a PCV valve on the 91 3.3L you have to tilt the whole engine forward and it is located UNDER the rear valve cover.
The guy then told me I should check the EGR valve but we couldn't find THAT part either! I stopped on the way home that day at Autozone, Advance, and NAPA and no one could point it out to me on my car and all 3 places said there was no EGR valve in their parts database for this car/engine combo and that they had no way to obtain that part.

My question is, based on all of this plus the codes posted below, is it more likely to be a bad computer, mass airflow sensor, EGR valve, PCV valve, or something else entirely? Keep in mind after changing a lot of the parts on the list below the computer still shows them as being bad. With xmas coming and having 2 children to shop for, we have sunk enough money in playing hit and miss and would prefer not to keep replacing stuff randomly.I can post pics if any are needed.

15 - ECT sensor indicates low temperature, or ECT sensor open

16 - DIS circuit fault

16 - Distributor ignition system or Opti-Spark ignition timing system, low resolution pulse

16 - Missing 2x reference circuit

16 - Transmission speed error(models with 4L60-E transmission or 4.3L S and T vehicle with manual transmission)

16 - System voltage out of range

21 - TPS circuit open, or voltage out of range(probably high)

21 - Grounded wide-open-throttle circuit

43 - ESC unit circuit fault(Buick and Oldsmobile)

43 - TPS out of adjustment

43 - Left oxygen sensor signal rick(1990 and later Cadillac)

43 - Knock sensor signal error


Cj Stalling When Idling


Stalling Out


11 Answers



October, 17, 2007 AT 5:30 AM

Make sure the charging system and battery is good-sensors/actuators relies on correct voltages.

Check the idle air control valve take it out and clean it.

Am also looking at the PCM



October, 19, 2007 AT 12:04 PM

Well there was a missing gasket between the Mass Airflow Sensor and the intake and on top of that on the electrical part of the sensor 1 of the 2 wires was brittle and was broken in 2. This morning picked up a new Mass Airflow Sensor at Autozone and put it on, the car does run a little better BUT very occasionally it does still try to stall. On the agenda today since I spent most of the money this week on the sensor I am planning on putting in 6 new plugs and the PCV valve I had purchased. I believe my PCV valve is on the rear of the engine under the valve cover and will require me to tilt the engine to reach it, so I might or might not be able to get it today.I will reference my repair manual regarding the idle air control valve and try to clean it today also. As for the charging system/battery, the battery is 1 week old with a 7 year warranty and I will have to check with a friend to test the voltage on everything.
I am unfamiliar with the module/PCM so I will try to ask the same friend if he knows about them. Will post back anything I do and if anything has helped.



October, 20, 2007 AT 11:46 AM

Ok my Haynes repair manual does not show or tell the location of the Idle Air Control Valve for my engine. Also was looking to check the EGR valve but can't find it in the manual either for my engine.



October, 20, 2007 AT 1:33 PM

No.2 idle air control motor

No.12 EGR





October, 31, 2007 AT 7:57 PM

Ok well after giving the car a tune up and replacing the mass airflow sensor as well as taking off and cleaning the Idle Air Control, it is still running just as bad. If anything the new sensor is enabling the car to get even worse gas mileage as I seem to literall be getting far less then 10 mpg right now. Also worth mentioning in more detail is almost every time the car is shut off, it takes about 45 seconds to 1.5 minutes of steady cranking to get the car to start up, and when it does it spews out a large amount of black smoke. We are putting about 2 gallons of gas in the car each DAY for local driving.I seem to run to the grocery store and run a few errands and then 1 mile each way to work and back and then the car is back in empty.

I am still unable(and the local garages are unable) to find either the PCV valve OR the EGR valve on my engine, even after viewing the repair manual and the diagrams posted above. 1 place told me the PCV valve was under the alternator and that the alternator needed removed to access it, then the next place I asked told me the engine had to be unbolted in the front and tilted forward, that the PCV valve is on the rear under the valve cover.

My big thing right now is something I came across on accident. There is a known issue posted as a TSB service bulletin
It says : "93T04 NOV 92 Engine - Deceleration Stall or Long Crank on Start Up"

This is exactly the problem with my vehicle. Sometimes it stalls when coming to a stop and sometimes cranks forever before starting. However when clicking the link for it the site wants me to pay $25 to read it. Question being is there any other way to get this information without paying? I am sure that after paying the $25 I would read it then have to turn around and buy a part again. The mass airflow sensor was a couple of hundred dollars.



November, 2, 2007 AT 8:03 PM

Well after reading about how common it is for the ECM to fail on my make/model I bought one today and changed it myself, located behind the glovebox. It wonderfully fixed the problems BUT after driving about 1/2 mile the speedometer went to 0, the car bogged down really bad and would not accelerate, and now every time I let FULLY off of the gas pedal the car stalls/dies most of the time instantly.
After speaking to a friend about this he had suggested that I could increase the idle speed just a little to remedy the problem, but then another friend told me that if it is a Vehicle Speed Sensor problem that it would still bog down, that the idle adjustment would simply fix the stalling. He said that since it happened right after I replaced the ECM that he figures I have a loose ground or blown fuse or something similiar going on.
I do know that on the ECM on the right side is a mounting bolt that I could only get finger-tight, because the location is blocked completely from me getting any tools back there to tighten it. This allows the ever so slightest of movement of the ECM on the right side, but the bracket that bolt is on is plastic and I don't see where it would cause a bad ground. Just moving the wiring around while working in there might have caused this new problem? The check engine light does occasionally pop up, normally when the speedometer randomly moves, but then when the speedometer goes back to either 0 or 110 the check engine light goes out again.

What is your opinion please?



November, 2, 2007 AT 10:29 PM

Maybe all it needs is an idle relearn. Bur check the EGR before you do below.

#1 set the parking brake and start the engine. You can put it in park or neutral. You need to let the engine run until the cooling fan comes on or it gets up to operating temperature.

#2 After step one you will need to let the engine idle in neutral for one minute. Then you will need to let the engine run in drive for one minute. Remember not to touch the accelerator in this step and #1.

#3 Remove the parking brake and drive the car at 20%-50% throttle until it reaches top gear.

#4 Cruise at light throttle for 5 minutes.

#5 Allow for the vehicle to come to a stop, you can use the brakes if needed



November, 3, 2007 AT 7:05 AM

I have been told by 3 different garages that my 91 olds with a 3.3L does not have an EGR valve on it.

When I first put the ECM in it I let it idle in park for about 5 minutes it did perfect. I then took it around my block letting it idle itself along the whole way just to test to see if the idle got erratic or if it stalled like it did before.

The new problem didn't start until we hit the freeway, we got to 50MPH and the speedometer went down to 0 then the car engine slowed itself down to about 25 mph, kind of like when you drive a stick and downshift to slow down.

Now every time you start the car whether it is in Park/Neutral OR in gear if you completely take your foot off the gas it will stall out and the speedometer does NOT work.

I woke up at 7 this morning and retrieved the new trouble codes, which are the following : Code 28 - Quad Driver module circuit
Code 31 Park/Neutral Position (PNP) switch circuit

Is there a chance I just simply knocked a wire loose somewhere when I changed the ECM? While awaiting a reply I will go outside and check for loose wires.I do know there is 1 little wire outside that is unhooked behind the glove box but I didn't think I did that. I can take a picture of it later if it helps. Also if it would help I could record about a 30-second video clip of me starting the car and it stalling and such, and upload that to photobucket or somewhere.

I would almost think the junkyard sold me another bad ECM except that when I first put in in the car ran so great with no check engine light.

Something important to note, when the car was first purchased by us the engine cooling fan was wired directly into the fuse box which of course kept the engine overcooled. I had since re-routed that through a toggle switch that I can turn on at operating temperature. I was told this morning that the code 28 could be set because the ECM tells the fan to come on at the certain temperature and it doesn't respond which causes a code 28. Is this true? If so I guess would just need to address code 31.

After reading your post I decided to try 1 more time to let the ECM adjust itself to my car and " relearn to idle".I unhooked the battery to reset/clear the ECM, then when I hooked it back up I started the car, left it in park at idle and let it sit and run there for about 10 minutes until it was at peak temp. I then(since I have the kids at home and wife isn't here atm so I couldn't go for a long drive) drove it a few times back and forth in our driveway and the speedometer worked and it didn't stall. The Check Engine Light IS constantly on, displaying these codes : 22 - Throttle Position Sensor (TPS) or circuit - voltage low
28 - Quad driver module circuit
31 - Park/Neutral Position (PNP) switch circuit

When I go to pick my wife up in a few hours that should be a nice test of the new ECM, I will post back the results. Hopefully it is good, we already blew about $400.00 of our xmas savings



November, 4, 2007 AT 8:54 AM

The car seems to be doing much better. The only thing I have to really complain about with the new ECM is the odometer on the car is adding miles on like crazy, like every 5 seconds of driving it adds on another mile to the odometer. The numbers are constantly moving lol. We drove like 5 miles up the road the car says we drove almost 100 miles!

This ECM came from a junkyard so I was thinking that it could be faulty as well? It did fix the old ECM problems but it brought a few new problems into the car with it. With this " new" ECM the speedometer stops working occasionally and the odometer is the big issue because occasionally it starts rolling on the miles really fast. The car also stalls occasionally at times when it didn't before. Do you think the new ECM sounds like it needs exchanged?



August, 5, 2010 AT 2:10 PM

This is quite strange. I also have almost identical issues with my 1991 Ciera 3.3. The odometer and speedometer do things like race forward intermittently or not work at all, I stall out regularly also. I have replaved plugs, wires, air and fuel filters, cleaned my MAF, replaced my TPS and idle air valve, and if anything my problems are getting worse. My car has only 86,000 old lady miles on it. I am no mechanic, but I've never had a car confound me like this one!

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