Not Quite Misfiring On My 3.8

[Dawizman]

Ok, to start I have a 1996 Firebird 3.8L 5 speed and am currently having some major problems with it.

The problem is as follows:

When I start the car cold I can rev it to the red-line without a problem with the clutch in and in all gears.

Once the car starts to warm up I start to loose power. Its like I'm bouncing off the rev-limiter, except its at a lower rpm. The warmer it gets, the lower the rpm it starts at.

When it first kicks in its at about 4k rpm in first gear / neutral, and about 3k rpm in any other gear.

Then it gets a bit warmer and the rpm drops to about 3.5k rpm in neutral, 3k rpm in first gear, 2.5k rpm in 2nd & third gear, and 2k rpm in fourth.

Once it hits normal operating temp I pretty much have to have the pedal to the floor or the car 'bounces' or studders horribly.

Currently, since the problem started I have replaced the following:

-Spark Plugs (NGK Iridium's)
-Spark Plug Wires (High-Heat 8mm's with wire-loom all the way down
-Air Filter
-Fuel Filter

I also cleaned the MAF sensor.

The condition improved slightly with the above, but not too much.

So, from all that, what remains untouched that could be causing the problem?

Currently, I'm thinking either dirty/clogged injectors, or a clogged cat.

What are your thoughts?

Thanks In Advance

[vanbibber]

Re: Not Quite Misfiring On My 3.8

are you getting a SES light?

other things you might want to check... 02 sensors,coil packs,ICM and as you said the cat. check to see if any of the spark plug wires are touching the exhaust manifolds also and check to make sure the plugs are gapped right. and maybe try replacing the PCV.

there is a number of things it could be so im just throwing these out there.

[vanbibber]

Re: Not Quite Misfiring On My 3.8

also have you checked the fuel pressure?

[Dawizman]

Re: Not Quite Misfiring On My 3.8

I am not getting the SES light and I'm pulling no codes.

I'm going to grab a fuel pressure gauge tomorrow and see whats up. I sure hope its not the fuel pump.

Also, thatks for all the ideas. I'll grab a new PCV tomorrow too just for the hell of it. None of the wires are touching the manifolds and I checked from top & bottom in the dark while it was running and saw no evidence of arcing.

[slow6]

Re: Not Quite Misfiring On My 3.8

the computer is tuned to only rev up to like 5900rpms or something like that

[Dawizman]

Re: Not Quite Misfiring On My 3.8

Well, I put the new coils on today and there is no improvement. I'm going to get the feul pressure gauge on it tomorrow to check if its the fuel pump or not.

How hard is it to clean a clogged injector?

Could a clogged cat be causing these problems?

[Dawizman]

Re: Not Quite Misfiring On My 3.8

Im also finding it frustrating that I get no codes at all.

[Dawizman]

Re: Not Quite Misfiring On My 3.8

Just an update.

I checked the fuel pressure today when it first ran and it was running good. It was about 46psi engine off, 44psi idle.

Then, I drove around a bit, got it missing & bogging, came home & re-checked and there was no difference at idle and it only fluctuated a few psi when I revved it and got it to bog out & stall.

So hopefully that means my fuel pump is good and I should be looking at the CAT, ICM & Injectors.

What is involved in testing the ICM?

How should I check the Cat?

What is involved in cleaning an injector?