[AnglicoGT98]

i'm having a problem with my newly installed exhaust system. i have a '98 gt that i just put a MAC off road h-pipe and a MAC axle back exhaust(1 muffler on each side) on. i bought new up stream o2 sensors and put them in, but i'm still getting some nasty lag....the car wont even accelerate well...and it starts shaking in low and upwards of 3k RPM...i was told about the MIL eliminators but my check engine light isnt on...i know that it is not anything internal because i didnt have this problem until i changed my pipes...here is everything i have done to trouble shoot this...someone HELP!!

-new o2 sensors, disconnected the battery and waited, i have the MIL kit comming just incase and i'm gonna try and see what a Diablo can help me do...

if anyone has ANY suggestions please let me know...i'm starting to get pissed! thanx


1998 mustang gt
-80mm K2 cold air intake
-80mm pro products throttle body
-80mm C&L plenum
-MAC off road h-pipe
-MAC axle back exhaust

[mdvaldosta]

The check engine light tripped by the lack of cats shouldn't affect the way the car runs, as the rear O2's aren't used for anything other than returning a yes / no as to whether the converters are functioning. MIL eliminators simply trick the ECU into thinking the rear o2 sensors are reading properly.

The only thing I can think of is maybe you installed the wrong o2 sensors on the front (though if that was they case they wouldn't plug in and you'd probably throw a code within a few minutes of running). I'd try installing your old o2's and seeing if that fixes your problem, at least you can eliminate that.

[AnglicoGT98]

when i had the old o2 sensors in it threw a code saying that one bank was running lean, another was running rich, and that one of the stock o2's were bad...i know i put the right ones in.....i just read on another forum that someone used a MIL kit on the front o2's and disabled their rears with a tuner....do u think that would work??

[Casper98GT]

The car was running ok before?

[AnglicoGT98]

yes..it ran fine with only the stock h pipe on...as soon as i put the MAC on it steadily got worse...i have narrowed it down to either the rear o2's or possibly the MAF could have gone bad...but i dont think it would have fucked it up that bad...do you think that idea with MILs on the front o2's would work??

[Casper98GT]

well you can try brand new 02 sensors that are the right ones or the old ones again. But youre idea in another post about putting the MILs on the front ones, no

[AnglicoGT98]

finally figured it out....it was that freak chance of coinsidence(sp?)...on the 96-98 gt's the front of the intake manifold had a bad wrap for leaking coolant from the front...well mine was leaking coolant and filled all of the driver side spark plug holes will coolant...so it wasnt sparking...fixed it guys, thanks everyone for the input!

[Casper98GT]

[AnglicoGT98]

hey man thats anough of that...haha...hey! it's my first stang, ya live ya learn right?? but my a/f ratio is still off...so i'm wating for my diablo

[Casper98GT]

Its ok, i wasnt laughing AT you. haha. I just asked if it was running fine before and you said yes. So i just couldnt see how it could have been running ok. Unless it just so happened the same night you did exhaust the plastic cracked.

[nHuman]

my car is laggin like this also, doesnt accelerate good and when its still cold it shakes like a muther untill it warms up and stalls like crazy

However im throwing some sensor codes, so I have to figure out what sensors i need to get.

Any suggestions on no2 sensors to replace?

[AnglicoGT98]

my orignal posts for this was actually not really the problem i came to find out..my plug holes were filled with coolant from a leaking manifold...but you might wanna try replacing the upstream 02 sensors..it might help...also, if your care is decently modded try getting your tps checked..i'm about to do that myself