Thread: Help: Having trouble after header install

Hi guys,
I have a 97 GTP and just installed aftermarket headers, crossover, midpipe, held together by band clamps and u clamps, I also replaced the rear o2 sensor. After the header install, I can't rev past 4k RPM in park or neutral and supercharger sound is gone. Also, the car bogs down going up hill 45mph and I feel like I have lost power on acceleration.

Weird thing is, I wasn't getting any reading from the MAF sensor and got the P0102 code right after header install. I fixed this by replacing the 21 fuse. The only reason I can think of it blowing this fuse is the precat o2 sensor wire was touching the rear header, I can not think of any other reason.

Right now, I am getting reading from front and rear o2 sensors AND the MAF and everything looks correct.

I do know there is an exhaust leak from the mid pipe near the rear o2 sensor. Only one bolt in the flange as the other bolt was seized and snapped off when taking it out. I doubt this is what could be causing it, but just wanted to throw that out there. No other exhaust leak that I know of.

I personally think it could be a vacuum leak or maybe I put a vacuum line in the wrong place? I took apart a lot of the vacuum lines, does any one have a good diagram to see where each vacuum line goes? Or does any one have any idea what could be causing this problem? No check engine lights yet, although I am expecting the p0420 code to pop up anytime now

Originally Posted by Scottydoggs

your hitting the rev limiter in park. its normal.

and you loose boost psi with headers if you had 7 or 8 stock you'll have 5 now. the o2 wire would blow the fuse if it melted and then making the maf not work and could be why it was dogging up hill.

Thanks for the reply. I am fairly new to superchargers. I did not know that headers would cause me to loose boost.

As for trouble going uphill, this was after fixing maf.

if it is still on the stock tune maybe that's the issue? Needs a tune?

Originally Posted by Scottydoggs

your hitting the rev limiter in park. its normal.

and you loose boost psi with headers if you had 7 or 8 stock you'll have 5 now. the o2 wire would blow the fuse if it melted and then making the maf not work and could be why it was dogging up hill.

not trying to thread jack but why do you lose boost after headers? loss in back pressure or?

Originally Posted by gtpwannabe

not trying to thread jack but why do you lose boost after headers? loss in back pressure or?

Increased engine efficiency = less boost. That's why we pulley down in the SC world...to get back the boost we lost during increases in efficiency. We do NOT go to a smaller pulley just to increase from say 8psi to 14psi...because you really gain nothing from that other than KR with the SC.

Ok I can understand the loss of boost but when I accelerate, car doesnt accelerate smoothly as it used to and bogs down under throttle. I'm fairly new to superchargers and I know since it's belt driven, exhaust gas isnt recycled... but if there was a leak in the crossover pipe or the exhaust manifold, could it cause this?

It is stock tune.

Originally Posted by Scottydoggs

if that o2 wire is melted it may not be working. repair the melted wire area. no o2 working will make the engine over fuel.

in the original post he said that he fixed the o2's and that they are working.. so that can't be it if the o2's are working properly..

Yes both o2's are working. Rear is def working, brand new. Pre cat o2 I am def getting constant readings. I reinsulated the wires and tucked them safe. I know for sure its not crossing of plug wires. I actually crossed the rear ones and it misfired. I made sure each wire went to correct cylinder.
I have a feeling I didnt put vacuum lines in the correct place. I actually broke plastic vacuum line that is located on the passenger side that runs along close to the windshield cowel. I fixed that line but I could have connected it to the wrong place? Can anyone post pictures of their engines with close ups of vacuum lines?

You said the rear o2 is brand new right? Is it bosch ? Heard that bosch o2's are garbage..

Yes rear is brand new bosch but the rear sensor doesn't effect drivability. Waveform looks good, obviously it's out of range bc no cat