Had my car taken to the shop to check it out. Come to find out i had 2 exhaust leaks and supposidly i was only fireing on 5 cyclinders. Elimtated my backfire but it still seems like i've lost power after replacing my spark plug wires yet again. It seemed super fast after they supposidly "patched" my wires but when i took them off and replaced them there wasn't any visible dmg that i could see to them. Now several starts later it feels as if im lacking power. Anyone have any suggestions as to how i could test/replace whatevers going on? Kinda lost at this point. I can definetly tell the power loss after the first few drives. I think my Signature still tells all that was installed on my car over the summer.

You have headers, a cam, but no aftermarket PCM? Your stock PCM is probably retarding your timing because it doesn't understand the huge increase in engine power. Also, why do you have an exhaust leak with bran new headers? Is the leak from the downpipe back?

I think you missed something in his sig.

I interpret that loosely as "Tuned PCM for GT1 Cam" But I could be wrong. It'* not english, but it'* close.


Any time you start modifying a car and this happens, you dig your scantool out and start trying to find problems. And start working backwards from what you did.

Where did your PCM come from? Have you scanned? Do you even own a scantool?

I'd be interested in knowing more about these headers... I'd also be very concerned if it was only firing on five cylinders. How long have all of these modifications been on the car(which summer)? When was the lack of power noted(before the mods, after the mods? if so, how long did it take?)? What sort of exhaust setup is it exactly? Has the MAF been cleaned lately? Do you have any engine codes? Any KR, or other small things not mentioned?

Woops. Read right over the PCM. I am very curious as to where this exhaust leak is.[/quote]

How could you not know it was firing on 5 cylinders? Didn't you have a flashing CEL, or at least a CEL on full time? And didn't you notice the engine roughness?

Access to a scantool is definitely at the top of the priority list at this point. You need to scan the car and let us know what kind of codes you find, and we also need a detailed description of the symptoms. Post your findings here.

well,

to answer a few of your questions, the exhaust leaks were coming from the EGR valve one of the two tubes were supposidly completly crushed and where the downpipe for the headers connect, the bolts were lose causing slippage of the gasket.

Also as far as the 5 cyclinder thing goes, there was an extreme amount of backfire going on and i did notice it. It happend during the winter when i got stuck and soon after i started hearing it. My only assumption is that the headers touched an unpertected spark plug wire and burnt threw causing one cylinder not to fire. But yet again i saw not visible dmg to the wires when i took them off except for one that look shaved off during some sort of reinstallation when we took them off at some point. Other then that they all looked fine.

Also to clearify i got all of my parts from websites listed on your site and a bunch of help from one of the members here. i forgot his nickname on here but he was a prime member. he wrecked his N/A awhile back. he had the custom bmw headlights body work and engine completly redone. A majority of you should remember. But the cam came from ZZperformance and the headers from 3800 website.

As far as the when i noticed the lack of power it was right away when i was driving to work and just here lately i decided to get it fixed. Its no longer backfiring but it just seems like its lacking power. Certain times it feels like it had more lower end power then here recently it just feels like its lost its balls. Im not sure if i have a faulty spark plug wire/spark plug or what. But where could i get one of these scan tools?

Thanks for all your responses.

~Aaron

oh forgot something... the PCM also was tuned from ZZperformance specificly for this GT1 cam. As you all know there isn't much room for all of the mods that you have on your ride. I tried to fit them all on there as best i could.

Yep, I was the one who told him to go with that setup.
I also remember saying to get a scan tool over and over.

Aaron, is there currently a check engine light of any kind (flashing or solidly lit)? Are there any stored codes in the system? Also, do you know how the EGR tube got crushed, and is there any chance the O2 sensor was damaged at the same time. It would be extremely helpful to have some scantool data. See if you can get a scan with some of the following parameters:

Throttle position
MAF sensor frequency or voltage
Intake air temperature
Long term and short term fuel trims
O2 sensor voltage (and general behaviors of the O2; i.e., is it at a constant voltage or jumping around)
Knock retard and knock sensor count
Misfires or misfire counts per cylinder
Air/fuel ratio
% engine load

See if you can get a simultaneous scan of these parameters. Having multiple "frames" of data with the varying relationships between these numbers can tell a lot about how the car is running.

Also, did you just get the exhaust leaks fixed today? If it'* a fairly recent fix, the lack of power could have come from the knock sensor hearing false knock from the exhaust leaks. It'* a fairly common scenario with a leaking exhaust. Other than that, supply us with all the data you can get.