cliffyk

[/align][/align]Yup, this whole "back pressure is necessary" thing does not want to die--it seems to be some gross mis-understanding of how header tuning and scavenging works, that gets mentioned anytime someone loses power after modding the exhaust in any way...[/align]

GhostRider02GT

Now, running cut outs right behind the manifolds or headers, will make you lose power on a mostly stock motor, not because of the lack of back pressure, but because the loss of the scavenging effect of the x pipe.

edit: sorry to hijack thread [sm=imsorry.gif]

whiterabit998

so wouldn't the mufflers make enough back pressure to run right?

GhostRider02GT

The back pressure is not an issue.....

2002GTAUTOVERT

ok guys listen up. BACK PRESSURE CAN BE AN ISSUE. BUT unless you installed 4+ inch piping on a stock motor, it wont be an issue until then.

2 things that jump out to me, are (and i dont mean this being a dick)

installed the 02's on the wrong end
Packing material left in the H pipe

possibly, if your H pipe was supposed to go a certain way, could be backwards. (only heard of this once but even then it didnt cause too many problems besides a popping)

99MustangGT_UK

I installed the eliminators on the sensors AFTER the cats - i.e. on the pairtowards the rear of the car, furthest from the engine. I also made sure that each sensor went back in it's respective location (the connector plugs seem to be colour-coded anyway).
There's definitely no packing material in the H-pipe. Surely it wouldn't have run well at first if it was anything like that? And one tailpipe would appear blocked? Also, it revs quickly and freely (but quietly) if I blip the throttle in neutral.
How can I get it out of limp mode?

99MustangGT_UK

Note: I meant to say that I installed the sensors AFTER where the cats used to be. But I guess you all already knew I meantthat!

Derf00

I saw it mentioned that the CEL/SES came on..did you run a code check to see what codes came up?!

99MustangGT_UK

No the SES light has never come on. I just disconnected the battery anyway in the hope of resetting the PCM and fixing the problem.

99MustangGT_UK

Well I finally had another chance to get underneath the car again today. I found the problem - the fibreglass from inside the bullet-type mufflers behind the H-pipe had come loose andwas clogging up both exhaust pipes inside the mufflers (just before the bend up over the rear axle). After several hours trying to getthe fibreglassout with various tools (bits of bent wire)I gave up and sawed through behind the mufflers. They were completely blocked! I'm amazed the car ran at all, let alone reached 40+ mph! Tried the car just now with no mufflers on and it runs really well (but far tooLOUD!). Next time I've got a day off I'm hoping to clear out the mufflers, weld them back to the pipes and re-install. Good job it's not a daily driver!Thanks to everyonewho tried to help. [sm=smiley20.gif]