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poor fuel mileage with zzp 1.0 pcm

99GPGTP

99GPGTP

New member
heres the story. the transmission went out in my car 2 years ago. i just recently for it fixed.while the car sat the fuel pump went bad, i installed a AEM 320lph pump. i put new oil pan and timing cover gaskets on my motor while engine was out. Installed a ported m90 housing. and a zzp 1.0 pcm. car was only getting 13-14mpg around town. and 15-17 on hwy. which is almost half of what it used to get. i changed the injectors, o2s, tried a new mass air from a friends car. installed an adjustable fpr. even went back to my stock m90 housing. none of these changes made a difference. 3 days ago i put my stock pcm back in my car and the fuel mileage went back to 28-32mpg on hwy and 20-23mpg around town.

has anyone else run in to this issue before or can tell me what i need to do to get my mileage back up with the zzp 1.0 pcm
 


They've probably done something in the programming. I doubt you're gonna get good mileage out of the ZZP one.
 
I ran a zzp pcm on my first grand prix and still got reasonable gas mileage. not sure why yours would be different.
 


My old ZZP 1.0 tune was extremely fat as well. Especially on cold startup and idle. Turned my good lookin tips all black is was so bad.
 
Trans has same gearing. Did add a 2500 stall. But when in lockup it shouldn't matter. I wonder if i would hurt fuel mileage by putting the ported m90 back on.
 
Maybe they avoid leaning out by dumping fuel and killing the efficiency? You've modded, are you monitoring? What's your afr?
 


I had a ZZP "Custom" can tune for my car. My LTFT's were ALL over the place, I mean +/- 17, it was insane, and my AEM Wideband would peg out at 10.0 at WOT.

I have heard their tunes run rich, and my Wideband would clarify that - but only at WOT. Not sure if this matters, but my cruise timing on the highway with the ZZP Tune was roughly at 20* - not sure what stock is, though.
 
99GPGTP said:
I will recheck my ltft. Last i saw they were up to +25 at idle
Click to expand...

Same here with ZZPoo tune.

If you get 0* KR with your stock PCM, why bother using the ZZP one? Try to get an in-car tune, get a tune from Reptile (on this forum), or get a tune from Overkill Motorsports.
 
Yep go with Retile or overkill i think overkill gives a $50 discount if you have some other companies tune and you go will one of theirs.
 


I'm driving 70mph cruise set. And my ltft is -11 and stft is 1 front o2 is reading 500-900mv. Baro reading 14.1psi
map @ 4.4-6psi
 
Changed mass air and front o2 sensor. No change in fuel mileage. Still averaging 18mpg. Is the aem 320lph pump just way to much for my setup?
 
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