RB25det VVT, TPS, intermitent cut out, Solved

[rayaapp2]

So Ive been sorting out an S13 with a series 1 RB25det in it. Its had a slue of problems. One of which I thought Id share with the board here.

 

The car would idle just fine and rev up in neutral well. The moment you drove the car down the freeway around 60-70mph during cruise the car would sometimes just cut power. It would also act up occasionally while under light throttle in other places under load. The problem finally got so bad that it would act up at idle when it got hot! I traced out the wiring harness, discovered that the throttle position switch isnt used by the ecu btw!, wire jiggle test, checked my ignition coils, checked my plugs, and all the other in depth checks for diagnosis. They yielded nada! The problem was still there. What is interesting is that engine temperature was affecting the issue as it would not have issues when cold.

 

When the problem became so bad that it was affecting idle I could hear the VVT solenoid chattering with engine stall... Then I knew I was on to something.

 

This is a common problem on most vehicles, but it was accentuated by the VVT, and fuel management into causing a weird stall! Apparently the TPS sensor had a bad spot! As the throttle passed over the bad spot not only did it freak the ECU out and stall the engine, but it accelerated the wear on the TPS sensor. I grabbed another used sensor out of my stash and without even installing it, plugged it in and suddenly everything worked great! I didnt even have to ohm out the old sensor. I reset the good part onto my throttle body to FSM specs and Ive been driving it all week now without any more hick-ups!

 

Hopefully someone that's having similar issues finds this and saves themselves some time. Its a common problem that for some reason I had not thought of during my diag.

 

Ray A