O/R H-pipe, now Idle Probs

KeithGT · Nov 2, 2005

first of all, hi everyone, new to the board, now down to buisness

Today, i installed an O/R H pipe on my 93 GT. everything went pretty smooth, had some prob with the O2 sensors so i just ended up replacing both of them, brand new. re-hooked up the EGR, all good. fired it up, damn this sounds good, can hear a couple leaks, no biggie, ill take it back off in a couple days, file the rust off the points where the H pipe meets the headers and the cat back. take it out, damn nice power difference, drive it for about 10 mins, come up to a stop light and my idle drops to like 300 R's then back up, then back down, back up, so i take off again, everything is good while driving. but at idle after its been running for a couple mins its dropping to around 300 Rpms then coming back up, dropping. i unplugged the EGR, thought it was just acting weird, same thing, no difference. right now its sitting in my garage w/ the batt unhooked hoping it just needs to get a good resetting. other than that, any other suggestions? i did check for vacuum leaks, no luck...anything will help.

thanks in advance
Keith

RacEoHolic330 · Nov 2, 2005

i was gonna suggest resetting the ecu, but you got that covered. Hopefully that will help out. I had some idle issues at one time and pulling the battery cable fixed it for me. Keep us updated

CManT1914 · Nov 2, 2005

You unhooked the EGR doing a mid-pipe swap? Is the fox setup different than an SN95? The only thing the EGR hooks up to on ours is the headers.

A surging idle can be caused by a vacuum leak. Does it take a while for the motor to idle back down after revving it? I might be talking outta my a$$, but something seems to be missing. A mid-pipe swap is pretty straightforward. I'd say it definitely has to do with your EGR you messed with. Tried pulling the codes?

KeithGT · Nov 2, 2005

yeah, on mine theres a pipe that come down and connects to the H pipe, im pretty sure it has to do with the EGR. No codes, except for when i unhooked my EGR to see if it stoped the idle from bouncing, so the code will be EGR unresponsive...for obvious reasons....and yeah, i did check for Vacuum leaks, i couldnt find any, i suppose its possible i missed something....come right back down after revving, no hanging out....

KeithGT · Nov 2, 2005

just went out and looked, the tube im talking about that i unhooked on the H pipe goes up to the back of each head, then into the smog pump....air pump..whatever

CManT1914 · Nov 2, 2005

Okay, see I thought you were talking about the smog pump and had the two confused, but I wasn't sure if foxes had a smog setup. There are several vacuum lines coming off the smog pump hoses, check those and make sure they aren't loose, broken or anything. Other than that, reset the PCM (unhook the battery and hit the brakes a few times, then leave it for about 10 minutes) and see what happens.

ninety15.0 · Nov 3, 2005

Pull codes...if anything comes up fix it. then take it out and beat the hell out of it...that normally helps! haha....maybe check your IAC...pull it off and clean it real good.

jrichker · Nov 3, 2005

See the sticky "Help me create the Surging Idle Checklist" at the top of the forum for help with your idle problems.

Paul Perreca · Nov 3, 2005

when i swapped my H pipe, i didn't do anything but that - n it was fine, i did the headers n h pipe at the same time, n i took the battery cable off while i did it because thats just like our standard proceedure, we always take it off - neway- to get the o2 sensors out of the old H pipe, we had to use a torch to heat them up, than break them loose w/ adjustable wrench (while burning the **** out of our hands) and than we put the sensors into the new H and Vuala - put the H back where it goes w/o cats, and sweet, i had new exhaust sound lol

KeithGT · Nov 3, 2005

yeha, i did read he surging idle sticky....after i postd this. sorry, unhooked the battery over night, nothing, getting ready to clean the IAC right now and see what it does...thanks for your help guys, if anyone else has any suggestions, much appreciated...

KeithGT · Nov 3, 2005

Could a nasty ass exhaust leak at the headers cause this? i think the flange on the H pipe is too big for the headers....

CManT1914 · Nov 3, 2005

KeithGT said:
Could a nasty ass exhaust leak at the headers cause this? i think the flange on the H pipe is too big for the headers....

An exhaust leak can cause a surging idle, but I doubt the flange is too big. Aftermarket h-pipes are designed to work with stock and aftermarket heades both.

KeithGT · Nov 3, 2005

when i pull a vacuum line and cause a vacuum leak, the car steadys out pretty well....does that make any sense?

CManT1914 · Nov 4, 2005

KeithGT said:
when i pull a vacuum line and cause a vacuum leak, the car steadys out pretty well....does that make any sense?

Not to me... TTT for you

KeithGT · Nov 5, 2005

my H pipe just wasnt sealing up right, i took it off last night, put the stock H pipe back on and the car is fine now....exhaust leakamnit: ..crazy.. thanks for your help CManT

CManT1914 · Nov 5, 2005

KeithGT said:
my H pipe just wasnt sealing up right, i took it off last night, put the stock H pipe back on and the car is fine now....exhaust leakamnit: ..crazy.. thanks for your help CManT

What brand was the h-pipe you bought? Did you buy it new?

2000xp8 · Nov 5, 2005

KeithGT said:
first of all, hi everyone, new to the board, now down to buisness

can hear a couple leaks, no biggie, ill take it back off in a couple days, file the rust off the points where the H pipe meets the headers and the cat back. take it out, damn nice power difference, drive it for about 10 mins, come up to a stop light and my idle drops to like 300 R's then back up, then back down, back up, so i take off again, everything is good while driving. but at idle after its been running for a couple mins its dropping to around 300 Rpms then coming back up, dropping. i unplugged the EGR, thought it was just acting weird, same thing, no difference. right now its sitting in my garage w/ the batt unhooked hoping it just needs to get a good resetting. other than that, any other suggestions? i did check for vacuum leaks, no luck...anything will help.

thanks in advance
Keith

The leaks are causing the problem, they are in fact a big deal, especially if any of them are coming from the header to h pipe flange.

Edit:, guess you figured it out already, i should of scrolled down and read the whole post.

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