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Dave Nova
Dave Nova, Chevrolet Technician
Category: Chevy
Satisfied Customers: 19451
Experience:  ASE Master Certification. GM World Class Certification
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Hi guys, Im having a problem with my 92 Olds Cutlass Supreme.

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Hi guys, I'm having a problem with my 92 Olds Cutlass Supreme.
3.1 MFI
Depending on which site I pull up, here are the fault codes and (hopefully) descriptions. I included vin in case that helps you with codes and engine.

22 tps undervoltage
32 abnormal manifold vacuum egr
33 map sensor voltage hi
35 idle speed 300 rpm hi or lo

I loaned my hi mile but good running Cutlass to my daughter. A couple of days later she called and couldn't keep it running. When the car is cold, it will start and run OK for about a minute then starts missing. It will continue to idle although rough. If you crack the throttle at all it dies. Sounds like it is loading up at idle. If you let it set for a couple of minutes and try to restart it, I have to hold the pedal down to clear it out.

I know my way around the engine and do all of my own work, but I don't know how to go about diagnosing the fault codes. Advice appreciated. Let me know if you need further info. Tom

This is a lot of info. to cover so bear with me .


The code 22 sets when the throttle position sensor voltage goes too low. This can be due to a bad sensor or wiring.

The code 32 sets when the computer commands the egr valve open but does not sense that egr flow has taken place. This will need to be fixed, but does not affect the way the engine idles.

The code 33 sets when MAP sensor voltage is high, this can occur when the idle is rough or unstable, this code is more than likely set as a symptom of the problem, not the cause.

The code 35 sets when the computer is unable to properly control the idle speed.


My suggestion is to start diagnosis with the throttle position sensor. Use a voltmeter to check voltage at the throttle position sensor connector. You should have ground on the black wire, the gray wire should show 5 volts with the key on. If both of these are correct, test the blue wire (with key on and tps plugged in) voltage with throttle closed should be 0.5 volt. and with throttle wide open should be approximately 4.5 volts. Let me know what you find and we'll take it from there.

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Customer: replied 7 years ago.

Good info Dave. I understand it is alot of info. No rush. I appreciate your help. I will check and get back to you. I'm going to accept now. Follow up questions OK?



Customer: replied 7 years ago.

5 volts from blk to gray. .575 volts throttle closed. 4.505 wide open.


OK. Here is what has happened. Checked voltages as per your direction. Plugged tps back in and started car. Check engine light is now out and it stays running. The engine is still missing a little and throttle response is not crisp, sort of has a couple of dead spots when you push on the accelerator. Could be the idle air motor a little lazy, (I put a used on in awhile back) or do I still have issues to resolve?


The strange thing is, is that I had already disconnected all of the plugs to idle air, tps, map and egr suspecting a bad connection. This time when I plugged tps in it is running. I haven't taken it on a road test, but at least it is letting me open the throttle.





Follow up questions will be great. The problem may be a broken wire at the tps. Flex the wire harness at the sensor, and gently give each wire a pull with the engine running to see if the idle changes..
Customer: replied 7 years ago.

Dave, I pulled, wiggled and tugged and of course cannot duplicate the problem. The car was compeletly undrivable before.


I took it around the block and up the hill. Throttle response is not the best and it is still missing and died once while pulling the hill but restarted. Power seems down, but no check engine light now.


Alzheimers time. I had a small engine fire due to ruptured fuel regulator about a year and half ago that singed some of the wiring around the trottle body. Mostly damaged the corrugated insulation but I see that the tps plug is somewhat melted. Sorry forgot about all that till I pulled the plug off.

Seems to be working but I think I'll go to the junk yard and get a plug and splice/replace.


Do you think I just need to do a tune up or is there more that needs to be done with the egr?



Yes, I would replace the connector. These connectors are available at your local parts store and GM dealer pretty cheap. This may be a better option for you than trudging around a junkyard trying to find a decent connector. The problem with the egr is that the passage is most likely clogged with carbon. The computer will command the egr valve on while driving and look for the O2 sensor to go lean momentarily. If it does not see the proper response, it will set the code 32. Remove the egr valve and clean the passage behind it. This is not the easiest thing to do, since the passage is not straight. Use of carburetor cleaner spray and a 6" length of coat hanger wire are the tools for this job.
Customer: replied 7 years ago.

Ok, I unhooked the battery to reset ecm. I reconnected and started the car, revved it a few times and all seems ok, other than running a little rough. Shut off and rechecked codes. All clear.


Last question! I've had the egr valve off previously. Am I cleaning the passages in the valve or the manifold?






The passages in the manifold. There will be 2, one for the exhaust coming into the valve. This port will be clear. The other passage feeds from the valve into the manifold, this is the one that will be full of carbon. If you are confused as to which one is which, remove the valve and start the engine, it will then be obvious that one is blowing out exhaust.
Customer: replied 7 years ago.

Cool! I know exactly what you mean. I appreciate your time and knowledge.


Positive feedback has been posted and bonus on the way.


Thanks Dave.



Thanks. If you need additional assistance, I will leave this question open so feel free to log back in and ask.
Customer: replied 7 years ago.

Hi Dave, I finally got around to installing the tps pigtail on my Cutlass. I also replaced the idle air motor.


Unfortunately still runs like crap. It will start and run pretty good for a couple of minutes until the engine gets a little heat in it and then it starts missing badly and develops huge 'dead spots' in the throttle. Ultimately you can barely get it off idle after that without the engine dying.


I replaced the plugs as they were old, no difference. I did pull the egr and it wasn't plugged but I cleaned it up a little anyway. Also went back through the test procedure we discussed before and the tps voltages are right on.


I checked them with the engine running and got it to a point where it would die and the voltage held steady where it should have been. The voltage increases and decreases smoothly as I work the throttle.


I double checked the computer and there are no codes showing up and no check engine light.


I'm really puzzled. Seems almost as though the ignition is being turned off intermittantly after it runs for a couple of minutes.


If you have any further suggestions, please let me know. I will gladly pay for your time.


Thank you! Tom

Customer: replied 7 years ago.

Also, fuel pressure regulator was changed out about a year ago, fuel pump about 2 yrs ago. Fuel pressure holds steady at about 40 psi at all times.

I've swapped out the mas and map sensors from another car with same result. I also hooked a new spark plug to the front 3 cylinder wires and good spark is maintained even with it running rough.

About the only things I can think of is a problem with the oxygen sensor or possibly an injector issue?

Originally talked to you 2/16/'10

Is there much more I can check on my own?