Fuel Cut, No Boost leak and keydiver chip... WTF MATE?

DSMturbo2 · Jul 25, 2008

1991 GVR4
2.0
Big 16g
FMIC
RC550
Key diver chip tuned for setup (stage 3)
AFC for fine tuning

3" turbo back
2g MAF
Zeitronix (o2,Boost PSI,EGT)
BR7es
20psi boost at a rich 10.6 AFR (2 counts knock maybe)
MMCD

Now to the good stuff.

So doing a full third gear pull turbo hits full boost and randomly but always at full boost (20psi). I hit what feels like fuel cut. BAM brick wall... AFR snaps lean for the blink of an eye...

Ok sounds like a boost leak. so I do the test...

Boost leak results. 7psi barely a leak at BISS, 17psi small leak at TPS (checked with soapy water barely a bubble every 6 seconds. Nothing to lose sleep over.

So I log this incident. everything looks normal AFR stay steady aroung 10.6 - 11.0 and all the sudden there is a hiccup AFR jump lean for a sec and everything goes back to normal. less than 4 counts knock throughout.

Interesting thing is during this hiccup all sensors seem normal. HOWEVER, TPS is reading 100% but injector pulse width drops to zero (most incidences it goes from 90%DC to 0-7%DC) fuel cut? its long gone?

WTF MATE?

The only thing I can think of is the ECU stops injecting fuel. What could cause this? Thanks for the space. Erik

drifte · Jul 25, 2008

What fuel pump? FPR? bfp on fpr?

OT: how on was your keydiver chip (a/F), did it require adding any fuel etc?

DSMturbo2 · Jul 25, 2008

here comes the beating. 255 purchasing a fpr this week. so running stock fpr. maybe a little over run but doesn't seem to be too bad? Think this could be related? I am well aware of the need for a fpr, but not really making the connection to this issue.

the keydiver chip was only slightly off on the high trims (within 10% max). the low is really close. I had attributed this to the lack of fpr. very easy to dial in with the afc. I just have been running it on the rich side due to some knock. Certainly worth the cash. It cant be beat.

drifte · Jul 26, 2008

I was just asking as I have the keydiver chip, was about to order my WB02, and had to go get myself a new engine, old junk walked on me.

As for the boost leaks, we boost leak tested mine, zero leaks anywhere (20psi) and I have had no problems like you speak of. IDK how low the tolerances are for leaks, but It would be worth a try to seal it up. We have a very similar setup, down to the high end afc the ballers use

DSMturbo2 · Jul 27, 2008

AFC and VPC's those are ballin' Dont have a VPC but one can dream.

Walking 6 bolt? good luck with that man.

I think i am ordering seals monday to fix the leaks around the TBody. Weighing options at the moment though.

code · Jul 27, 2008

when i was tuning my car the wideband was reading mid 10's and w.o.t. and i had similar problems. i pulled fuel a little to bring it to 11.1 or so and it ran perfect. i have no problems at all.

DSMturbo2 · Jul 29, 2008

code said:
when i was tuning my car the wideband was reading mid 10's and w.o.t. and i had similar problems. i pulled fuel a little to bring it to 11.1 or so and it ran perfect. i have no problems at all.

Did you log it and recall a drop in pulse width though? That is the part that seems so weird. I am going to get the small leaks in the TB taken care of then start leaning it a bit. Still seams odd though. Thanks for the help

DSMturbo2 · Jul 31, 2008

Well, Tonight it started doing the same thing under acceleration (even slight load around 4500 RPM and up. 100% throttle still goes to 0% IDC. Would a bad 2g MAF do this? its still reading normal values, no codes.

It was even doing this with the launch control activating. anything above 4500 RPM (basically no load).

I just tried replacing the injector resistor pack and that did nothing.

I may go switch to a stocker ECU and see what happens... this is crazy.

Fuel Cut, No Boost leak and keydiver chip... WTF MATE?

DSMturbo2

drifte

DSMturbo2

drifte

DSMturbo2

code

DSMturbo2

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