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Where'd all this damn fuel come from?

DSMopar

Proven Member
610
13
Oct 6, 2007
Vista, California
Current setup:

95 talon AWD
6-bolt swap, 2g head/intake
MHI E316G
560 evo injectors
255LPH walbro stock wiring
stock FPR etc
tuned with SAFC2
barometer wired with potentiometer to crank it below 73kPA (to avoid misfires due to 6 bolt swap)
VSRF front mount

the car was running fine for almost a year now on that combo with the exception of the front mount. I've been running with SAFC compensation around +7% (due to the barometer).

I JUST finished putting the VSRF front mount on with NO OTHER CHANGES. And it has been running incredibly fat at all loads and all RPMs. I have EVOscan and I confirmed the o2 is way high and the feedback trim is always negative. It was so fat that when going WOT it would bog and cut out.

Things I have checked:
- Boost leaks (fixed a couple large ones but now no significant leaks)
- Barometer still shows 71kPA which is where it has been set for a year now
- IAT reads correctly
- CTS reads correctly
- Input from MAF reads correctly (tried 2 MAFs). It's idling around 44hz straight MAF signal reading from the SAFC which is exactly where it was before the install

To get it to run correctly I now have it all the way at -50% at idle RPM, other low throttle settings are at -40%, WOT is at -25% across the RPM band. I checked with EVOscan and with those settings at WOT I get no knock and o2 is high like it should be. Going any richer than -15% causes it to bog and buck.

So with no other changes than the front mount and keeping in mind no boost leaks, where did all this extra fuel come from? The only things I haven't checked are fuel pressure (maybe stock FPR is ####ed up, or pump internal bypass died).

The only other thing I could think of is the ECU caps, I did hot swap the MAF connector by accident when I first got it running (started the car and it died, left key on and went out and noticed the MAF was unplugged so I plugged it in). With that said most ECUs are pretty robust for that sort of thing. Any ideas?
 
Last edited by a moderator:

DSMopar

Proven Member
610
13
Oct 6, 2007
Vista, California
Timing can cause bad gas mileage, not extra fuel

Ok so I drove it more tonight, now it's getting random misfires at cruise just as if I didn't dial back the barometer... double checked it and it's still at 71-72 kPA :confused:. Starting to think ECU is bad
 
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