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ZZP O2 emulator catless DP worse MPG's Codes

gtpeddie

gtpeddie

New member
Hey every one as some of you may know i redid my exhaust a few weeks ago on my 1997 GTP, and put my catless down pipe on its a 2 1/2" ZZP DP on stock exhaust manifolds. I have a P-log just not installed yet. So after redoing my exhaust i got worse MPG's then before, my thought was it was because i had no o2 emulator to think i have a cat. My exhaust set up is 2 1/2" catless DP, thrush glasspack as resonator, and stock mufflers no leaks. So ZZP was kind of slow at getting in my o2 emulator and i been driving around with out it for a while and best i was getting was between 16.6 and 16.8 mpg, before i was getting around 18.6 and 18.8. So today i got my o2 emulator and followed instructions to put it in (pretty simple didnt say anything about disconnecting the battery or anything) so i put it in started my car and same code was there (P0140 o2 sensor CKT no activity "bank 1 sensor 2") so i decided to erase the code, then it went away didn't come back after driving it for 15+ miles. So does this mean its working? But im still getting the same mpg's i dont understand i thought better flow would make me get better gas mileage? Any one have any thoughts on this or can help me out, would be greatly appreciated! And if my o2 emulator is bad i want to send it back ASAP before its to late.
 


The rear O2 sensor has nothing to do with the fueling in the pre 01 cars. Maybe you messed up a plug or wire when you installed the dp?
 
dsmuts said:
The rear O2 sensor has nothing to do with the fueling in the pre 01 cars. Maybe you messed up a plug or wire when you installed the dp?
Click to expand...

i don't think so the DP was pretty simple to install we did it on the lift and the guys at work helped and they have done a lot before, and i know these cars don't but i would just think that might have something to do with that because that's the only electrical i messed with.
 
Reducing back pressure isn't always the answer. Likely now w/o the backpressure you are using more rpm to get the car moving around town.
 


You did not say you got a tune on the PCM for the less back pressure you now have. So I agree with the last post, you should get more MPG after a good PCM tune. Yes if the code is not set then the O2 emulator is working. :th_winking:
 
You don't need a tune for just a dp. It doesn't make enough difference to throw anything out of wack.
 
Howdy All
I installed a zzperf. 2.5 SS DP with cat about two weeks ago. Took a 200 mile trip with it and my milage seems to have gone up a bit. I did not calculate but know how much fuel this trip takes as it is a regular one.

Before install I was clearing the P0420 regulary. Since new pipe no SES light.

Car seems to have more pep as well. Dont know about backpressure I went with the cat because it seemed like a good idea.

Later
Robert
 
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