1990 grand prix code 33

Hello, I have a 1990 Pontiac Grand Prix with 3.1 and about 200k miles (odometer hasn't worked in about 6 years). I recently put the ol' girl back on the road after sitting for 2 years and I'm running into a poor running condition. I had driven this car for 3 days since putting it back on the road and put hundreds of miles on it. The problem started when I went to start it one day. I cranked it for a split second (long enough for it to start usually) and the engine just fired once and sputtered. (Kind of sounded like it fired the engine backward... I only bumped the starter). So I just tried to start 'er again. Then it would just crank. I tested for spark and there was none. I have a spare computer, which I swapped to no avail. I went and picked up an ignition module the next day and decided to try to start it again before tearing into the car.. It started up but acted like it had a bad misfire. I assumed (oops) it was the ignition module so I changed it. Still had a misfire. I tested for spark at all coil packs and all seems good.

I figured I'd scan the computer for codes; it can't hurt. Well code 33 popped up. So I checked the vacuum line and wire connection at the MAP sensor. All seemed OK so I changed out the MAP sensor. Well it's still running like crap. It's like it's misfiring. Fairly regular misfire, but it seems more like 'blubbering' from too much fuel. If I can get it to idle it really chugs out the exhaust.

Why else would it pull a code for the MAP sensor? Could the poor running condition mimic the readings of a failing MAP sensor to the computer? How can I test the MAP sensor? (Although I'm fairly certain the new one is OK)

Any other ideas? Any help would be appreciated.

Reply to
Brendan
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I had a code 33 stored in the computer memory and have since tested and confirmed a low vacuum condition (about 10" mercury) I hooked a vacuum gauge to the vacuum line for the MAP sensor (and unplugged the MAP sensor wires) and started 'er up. It ran noticeably better without the map hooked up but still pretty rough.

I would venture to guess I have a rather large vacuum leak somewhere and I can't hear one. I took the EGR valve off (electronic solenoids version) and I can get air to pull through all 3 orifices. One isn't too bad but 2 leak fairly heavily. Does the egr valve shut these orifices off better when it's plugged in and operating? The valve assembly looks to be in very good shape with surprisingly little gunk buildup anywhere.

A new EGR valve is about $200 !!! And I'm still a bit confused as to why it' d go from running perfectly to very crappy in an instant.. Somehow I don't see how the engine firing backward momentarily would do this to the egr valve. Heh, I've had trouble with this car in the past where it backfired through the intake several times and it never did any damage. (Perhaps it set the stage?)

Oh, and just for the hell of it, and because the gasket set was so inexpensive, I pulled the intake plenum just to check the vacuum lines. They all check out good. Amazing the junk that builds up under there. :-D

Any ideas would be greatly appreciated.

Reply to
Brendan

The EGR should be shut tight, in it's natural state. Sonds like yours is broken. GW

Reply to
Geoff Welsh

Thank you very much for your suggestion.. I hope you're right! :-D

Reply to
Brendan

(You were)

Reply to
Brendan

I have a 1990 Pontiac Grand Prix LE, V6, 3.1L and I am having some issues with it. Maybe someone can help me. I had the Fuel Pump, Sending Unit, Fuel Filter and Fuel Relay replaced and it still will not start. It will run if you are spraying Ether into it then dies when you stop spraying. It is getting fuel up to the engine but it won't stay running without ether. Please, someone tell me what to try next!!!

Reply to
angie375_1

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