code 33 1990 grand prix

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 a 'blubbering' from too much fuel. Smells like it out the exhaust too. 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.

Thanks!

I'll do that tomorrow; I've given up on the damned thing for tonight.

I'm thinking of popping the intake plenum to check the vacuum lines in there. Is that necessary also for checking the pcv valve and hose connection? I've also read something about checking the egr valve for gunk holding it open. I remember loosening that pipe between the egr and exhaust manifold once before..... yick.

I gave that idea some thought myself. When I put it back on the road it was almost empty on fuel. I've since filled it up a couple of times.

I'm thinking of renting a fuel pressure gauge from AutoZone to check that out. Weird that it'd suddenly go from running perfectly to no spark, then this rough running.

I've had this car 9 years and the only recurring problem I've had with it is the no-spark condition. (Well, once I fixed the rear calipers with brass inserts)

Heh, well now I have spark!

I'm surprised the motor has held out as long as it has. I've read about head gasket problems; so far I've lucked out in that department. I've never even had the plenum off.... probably going to do that today too.

Thanks for the help.

That's often all it takes to jump time on a high milage engine. I'd check the timing belt/chain. H

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.

Oh GOD you did have to suggest that. :-D

Thank you VERY much for your suggestions.

Well, it turns out it was the egr valve not closing. How odd that it'd go from working normally to all 3 orifices (each with a separate soleniod to operate it) leaking.

So.... in the future I'll crank the engine until I KNOW it's started... no more bumping the starter because the engine starts to quickly normally.

I got the thing fixed and was driving it down the road (replaced ignition module and egr). About 5 miles away from home it dies as if I'd just shut the key off. So I'm thinking along the lines of timing chain broken (argh). But it cranks sounding normal... and it fired a couple of times for a split second.

Hmmm, that reminded me of the 2 other times I've had to change the crank sensor on this beast. So, $15 later it's back up and running again (for how long?).

So that one instance of the engine firing backward for less than a second blew the ignition module and egr valve. Also somehow messed up the crank sensor. Sheesh! I think I'll enter it in the demo derby this year.

Anybody ever convert one of these back to having a distrubutor? I'd consider putting a carb on it even to never have to deal with that damned distributorless ignition system again. 9 years and whenever there's a problem it's a no-spark condition. I've stockpiled a couple of computers and ignition module / coil pack sets... but that crank sensor is a bitch. :-D

Thanks for the help.

OK, this car is about to go to the scrap heap D-8

It died on me again... just croaked while going down the road.... no spark.

Until it cools off.

So I've replaced the ignition module and coil packs, crank sensor and the computer.... there's nothing else on this car that has to do with spark..... so would it necessarily have to be the wiring of the ignition system?

Anybody want a cheap grand prix that goes like hell until the engine gets hot? lol