1999 Regal Weird Problem

[thetenfold]

Hi, I have a '99 Regal 3.8 naturally-aspirated.

Problem history (maybe related): about a month ago, it started running really badly and would overheat quite quickly. It wouldn't go over 2500 rpm except in park/neutral it would hit 3000. A mechanic changed the cat conv on it and it seemed to run fine (even a little more power from the clean cat), however the CEL was still on as it was before. I read the codes before and after, and the codes are as follows:

P0102 - Mass Air Flow (MAF) Circuit Low Input
P0443 - Evaporative Emission Control System Purge Control Valve Circuit
P0449 - Evaporative Emission Control System Vent Valve/Solenoid Circuit Malfunction

I don't want to think it's the MAF because we changed it last year for a new one. Then, when the new cat was put in, the guy tested the MAF and he said it worked fine.

Here's the current problem: I started up the car this morning, and it started up fine. But, whenever I tapped the throttle, it would start to rev barely, then stall. In order to touch the throttle and keep it running, I had to put my foot down and stay there. It would start to go down, then (delayed) rev up. So after it stalled, I turned it back on and revved it a little more. As it hit like 2200 rpm, you could hear sloshing as if water were being let through the engine and it would stop after 20 seconds. When it started to slosh, the low coolant light came on.

Any idea at all what could be causing this?

[richtazz]

I would try unplugging the MAF, then see if it runs better to rule it out. If the replacement MAF was from Cardone, there's a good chance it could be bad, as they are bad quality. The two codes other than the MAF could be caused from a vacuum leak, so you may want to check your underhood vacuum lines for cracks.

[thetenfold]

Originally Posted by richtazz

If the replacement MAF was from Cardone, there's a good chance it could be bad, as they are bad quality.

I wouldn't suspect so. The part itself was like $230.

Originally Posted by richtazz

The two codes other than the MAF could be caused from a vacuum leak, so you may want to check your underhood vacuum lines for cracks.

Yeah I thought about vacuum leaks but never tested yet. I'll do that after it's done snowing and the driveway is plowed out.

[thetenfold]

Originally Posted by richtazz

I would try unplugging the MAF, then see if it runs better to rule it out.

I did that and it runs the same with the MAF disconnected as it does connected. Same problems with the throttle and all.

Originally Posted by richtazz

The two codes other than the MAF could be caused from a vacuum leak, so you may want to check your underhood vacuum lines for cracks.

Is there a cheap, safe way to check for leaks if I don't find any visual flaws?

[BNaylor]

Do you have the original Upper Intake Manifold (UIM) and Lower Intake Manifold gaskets? Hows the coolant level? The sloshing sound could be coolant being recovered through the reservoir back to the radiator.

[thetenfold]

Originally Posted by BNaylor

Do you have the original Upper Intake Manifold (UIM) and Lower Intake Manifold gaskets?

As far as I know, yes. What's the difference between upper and lower? The upper intakes air and has the maf, iac, tps and the lower is what exactly?

Originally Posted by BNaylor

Hows the coolant level?

I just topped it off actually. It's always had a brownish tint in the reservoir and sludge buildup on the rad cap. I read this could just be a problem with the GM coolant they use that causes sludge but I don't actually know the cause.

Originally Posted by BNaylor

The sloshing sound could be coolant being recovered through the reservoir back to the radiator.

That makes sense.


I'm still wondering why it has hesitation on throttle. What it does is when I tap the throttle and let off quickly, the rpm goes pretty low and will almost stall. That lasts about one second then it goes up to where it should have.

EDIT: I don't know if this is any useful info, but after I topped off the coolant, it would fluctuate from 1000 to 800 rpm down and up constantly (when cold). Then when the thermostat opened (when it was a quarter way hot), it stayed at a steady 800 rpm idle instead of the usual 1000.

[BNaylor]

Originally Posted by thetenfold

As far as I know, yes. What's the difference between upper and lower? The upper intakes air and has the maf, iac, tps and the lower is what exactly?

The upper is the plenum where the throttle body connects. Lower is below the UIM and connects to the cylinder heads. Both are common problems on the Series II NA 3800 engine. I replaced mine. It is not of matter of if they will go bad but when. The sludge means an issue with these gaskets.

Let me know if you need pics.

[DanHogue89]

Hi my Name is Daniel and I know What you problem is its your "mass air flow Sensor" search autozone its around 200. but well worth it. I had the same problem. whenever i started the car it would either rev like crazy or it would putt and die. then i would have to start it again. And every so often it would rev when i press the brake because what the mass air flow sensor does is reads the how much air is coming in the engine and if it thinks that your not getting enough it will rev the engine to make up for it missing the air. it has even died when i came to a stop because like i said it does think its not getting enough air and it will either rev the engine or kill the engine depending on how much air it needs. anyways if you have any questions please ask. Thank You Daniel.