I've got a customer who brought his car to me last week, says it's still hitting fuel cut. Problem is I've already installed an FCD for him. Only mods are DP, midpipe, and cold air intake. He says it never happens until an extended 3rd gear or 4th gear pull, and then only after 6500. Sounds like an exact desc. of boost creep, but why? Anyone else ever run into this?

 

Monitor the ouput voltage of the boost sensor at the ECU when boosting. The clamp voltage should be under 3.65 vdc. If over.....then adjust the pot in the fcd to a lower figure.

 

How do you know it's overboost fuel-cut?
Unplug the electrical connector to the boost sensor and see if you can duplicate the hesitation.
If it still hesitates with the boost sensor unplugged, it's not overboost fuel cut.


-Ted

 

good point, Ted. Just wasn't sure how much that boost sensor contributed to the fuel map at that rpm. Pump voltage is 12.6 under boost. Pump output is 86psi at tank, 64psi at rail. New fuel filter. Good engine grounds. No vac leaks, I'm just trying to eliminate all possibilities.

 

Just curious. Isn't 64psi rail pressure a touch too high? This thing boosting over twenty psi boost?

 

i get the same hesitation and i have the same set up "3-2 1/2 DP into a stock cat back" and i was told it was eigther my stock cat back was to restrictive or i needed biger fuel injectors.

 

have u seen this "fuel cut" ur self? maybe it's not even fuel cut at all and he's just incorrectly describing it...

I had a similar problem in my GTR... severe hesitation at full boost in upper rpm... the rpm just didn't wanna go..

later I discovered (after changing everything else) it turned out to be one of the coils... under low load it was fine idled ok and all.. but it was crapping out at high load...

 

64psi before regulator has been a pretty standard number on the TII's that I've tested.

 

Boost sensor does not affect fuel delivery under boost.


-Ted