My car has been doing this for a while and my lazy *** has just gotten around to trying to fix this since the weathers getting good.

My mods are just the basic headers, ory, lid. The car has new O2's and a new GMS 85mm maf. I am also running on the stock tune.

The car felt normal just cruising around but when I would punch it around 4500 rpms to redline the car would just start missing and popping. Also my gas mileage hasnt been that great, I always use good gas like shell or exxon 93 and Ive been getting around 220 miles to a full tank.

I just recently changed the MAF and the car has gotten worse. Now when I start the car it will hunt for idle for a couple of seconds and sometimes accelerating from a light with light throttle the car will buck and hesitate, its hard to describe it, like the car will just cut out for a split second and come back over and over again.

I think the problem initially started when my EGR bung on my header broke and I drove around for a week before I caught it. I remember I got terrible gas mileage to that tank because of the massive exhaust leak and after that the car just felt weak.

I have done logs with HPT but I dont really know what to look for, Is their anyway I can post it or something? One thing I know is that when I go WOT right around when the car starts misfiring the injector duty cycle is at 130%. This past weekend I hooked up a vacuum gauge to the car and it was only pulling 14 in.Hg of vacuum.

Since the new MAF I am getting the following DTC's: p0172 & p0175 fuel trim system rich bank 1 & bank 2.

I hope I didnt leave anything out. Please HELP!! I would like to get this fixed as soon as I can.

 

You might check your spark plugs. An exhaust leak can cause the O2 sensor to read lean, which would have caused the PCM to dump more fuel on that side of the motor, which might have fouled your spark plugs.

Have you tried going back to the stock MAF?

 

Im actually going to go back to my stock maf when I get some time later today, Ill pull some plugs while im at it. I would of pulled the plugs before hand but 1. its a pain in the *** lol and 2. I dont understand why the hell my injectors would be maxed out.

 

I hear ya. I'm dreading changing the plugs on my car. ;-)

The reason your injectors are maxed out is probably the same reason you received the fuel system trim rich codes, which is probably the same reason your car isn't running properly.

I have heard of issues with aftermarket MAFs being run with stock programs. Not saying that's the issue you're running into, but it might be, and swapping the MAF might help us narrow it down.

 

Ok, this is very strange. I put the stock MAF in which I expected would fix my problems when driving normally which it did.

Then a friend and I pulled 5 plugs. 4 on the passenger side, which is where the EGR bung broke, and 1 on the driver side. They all looked fine, but my friend said when he pulled off the #7 plug wire It was really loose. So we put dielectric grease on the plug wires, and put everything back together.

Took the car out and it ran smooth as hell, pulled hard and drove perfect. I also logged with HPT again and injector duty cycle at WOT was 80%. We didnt have time to hook up my vacuum gauge but im sure it would read around 20 in.Hg now. Also after driving around for a couple minutes the CEL turned itself off.

I guess my real question is why would the plug wire being a little loose cause the injectors to be maxed out? I really, really wish my lazy *** would have check the plugs and wires sooner. The car has literally been running like this since OCTOBER

 

A quick lesson your car had loose wire. Under heavy accel your combustion chamber has higher electrical resistance so your spark says, "hmmm, higher resistance through spark plug or lower resistance straight to cylinder head?" well we all know electricity likes the path of least resistance. That problem created an occasional misfire. Misfire=raw fuel and O2 getting into exhaust stream. O2 sensors measure O2 only not unburned fuel. O2 'sees' a lot of O2 and tells the pcm hey your running lean (even though you're not) so the pcm commands more fuel. Thus, the higher LTFT. This along with the fact that Big bore MAF's usually require professional tuning all add up to really rich A/F ratio. **catch breath**