Hi everyone so I have G37x sedan with stillen 3rd gen intakes, muffler delete , & invidia test pipes. I know exhaust ain't the best but it's temporary, anyways the car has been driving normal with stock cats but as soon as I installed the test pipes Service engine soon came up. Still was driving good for about a week but then outta no where i was driving down a road it felt like it loss power & didn't have much pull at all so I figured Limp Mode :/ Oh & code P0101 came up but I checked everything & it seemed fine cleaned Maf sensors cleaned throttle bodies. Would it be the test pipes causing this problem because it's not tuned? Any thoughts?

 

Obviously could be a dirty or faulty MAF, but that's usually less common than something like a vacuum leak that would cause it to give that code also. You gotta think what possibilities could put a MAF out of range, assuming the MAF is functioning properly. Something triggered it to go out of range. Even a short in a computer wire somewhere could cause this.

Have you checked for obvious signs of vacuum leaks yet? This motor has many vacuum lines. Could be a total coincidence and not related to your test pipe install at all or it could be something that was moved/shifted/broken during installation.

 

Thank you v1mirage I haven't seen any signs of vacuum leaks I'm gonna put the car on jack stands & check out where the test pipes are installed.

 

Remove your mods one by one starting with the last one.

Telcoman

 

You mentioned doing test pipes. I personally haven't messed with test pipes on this car, as I have High Flow Cats, but bad O2 sensors or clogged cats can also cause this code. I have a feeling it's directly related to your test pipes since you got the code right after the install.

Are you getting any other codes other than P0101?

Does the car run rough or okay at idle? Is the issue only under load? Does limp mode only engage when you try to give it power? Does limp mode go away when you recycle the ignition?

Do you have access to a scan tool to get the MAF readings and MAP readings? Try to wiggle the MAF harness to see if that changes the behavior. Check O2 readings also.

Easier thing to try: unplug the o2 sensors. They will function using default values if not present, but this is one of the simpler tests you can try. Maybe you have a bad or shorted o2 sensor. I have a feeling this is the issue. Probably damaged a sensor during installation.

One of the things you may have to try is to unbolt the test pipes and let them hang there. See if you can floor the car in PARK and see if the flow seems better. This basically bypasses any "back pressure" flow problems and lets you know if it's a problem with your test pipes or not.

Are you getting misfiring? Sometimes it's not enough to throw a code, so you need to check misfire data on a scan tool.

Also, are you getting good fuel pressure? You will need to check that as part of your diagnosis as well. Does the engine only bog down when you give the car gas?

This is all potentially related to your P0101.


EDIT: This link is interesting: Kinetix HF Cat Check Engine Light On - G35Driver

This guy had a leaky cat which caused that code for him lol. Check your test pipes for quality control. I never heard of this particular problem causing P0101, but it may be so!