I own a '93 Lt1 Firebird. I was out for a drive just now and some guy in one of those Neon SRT4's drove up along side of me. There was a huge stretch of road ahead of us with no car's anywhere in sight so I dropped it into second gear and nailed it for about 5 seconds or so. By that point I was about 5 car length's ahead. It was obviouse this guy didn't have much under the hood so I got off the gas. Then the car started running really rough and the tone of the exhaust was completely different. I came to a stop at the next intersection and the car stalled on me (it's an automatic). I started back up again and I got a code 33. The car's felt really weird driving home afterwords. It just doesn't feel as smooth as before under acceleration. I really hope it's nothing seriouse. Does anyone know what a code 33 is and how I can go about fixing it?

-Ps. It's a '93 so I'm pretty sure the code #'s are different from the other car's since it's speed desity rather than Mass air.

Ps. Again, I was on the bottle when it happened (if that had anything to do with it)

Please Help!!!

 

Code 33: MAP sensor signal voltage was too high (low vacuum) for 1 second when throttle opening was under 3% and engine speed was above 500 RPM.

 

Uhhm..... thanks. Now what the heck does that mean ? Do I need a new map sensor? What would cause the low vacume? Shoud I just disconect the battery and erase the trouble codes and see if the car runs better? Someone give me some suggestion's. I have to drive to work tomorrow and I don't want to risk causing damage to my engine by driving it if there something wrong.

(Thanks again for the response Compstall)

 

Can't help you out much with the code, I'm not sure what to make of it either. Is the engine making any strange noises or anything? How much were you spraying?

Well, at least this will go back to the top for you. I checked out your page, love your car.

 

I'm spraying 175 as I have been for the better part of the last 4 years. The engine bay is not making any noise's out of the ordinary. The exhaust tone, though, is different. I can't explain why, it just is.

So does anybody know what exactly this code means and what I shoud do about it? Thanks in advance.

 

Let's start with the REAL promlem here..... why on earth would you use Nitrous against an SRT-4?

 

you stole my post! LOL.."why N20 with a Neon."

Hey man, quit picking on those little Dodge Neons. They never hurt nobody. lol
Sure as I say this one will whip me one day!!

 

Basically, on a 93 the computer uses the map sensor to measure the manifold pressure and computes the fuel needed based on that. If the MAP goes out, you're going to run like crap.

I would say clear the PCM, and see if it comes back. If it does, try swapping the map out.

If you have a scan tool, hook it up and start the car. With the MAP connected if you're showing over 4.0 volts to the MAP, you've got a problem. Disconnect the MAP and if the volts drop to 1 volt or less, you either have a vacuum leak at the MAP sensor seal, a faulty MAP sensor, or an open sensor ground circuit. If it doesn not drop to 1 volt or less, you wither have a short in the circuit, or a faulty ECM.

Straight out of the service manual.

 

Thanks a lot. That was really helpful . Unfortunately, I don't have a scan tool, so I can't tell what the voltage is to the MAP.

I disconected the battery and when I plugged it back in and tried to start the car it wouldn't even idle properly and stalled on me twice. There was a loud "knocking sound" coming from the engine compartment but my fuel pressure gauge read a solid 44psi and my air fuel ratio was where it shoud be. The knock eventually disappeared after about 15-20 seconds and the "check engine" light popped up again. Guess what? Code 33 again. I'm just going to order one tomorrow at the dealership and hope it fixes the problem. How much are these MAP sensors anyway?

 

If you need to drive the car, just disconnect the MAP, it will run on default tables.

I picked up a MAP at Advanced Auto a while back for about $30 bucks I believe.

 

Thanks for that info. I never thought of doing that. Just one question though, what are the drawback's (if any) of running the car with the MAP sensor disconected? Would the car run rich, lean or what? I'm running a piggy back chip from PCMforless right now, would that influence anything?

 

Can't say for sure if it would be rich or lean as I don't know the default tables, but you'll probably notice less than normal performance and decreased gas mileage.