My car starts up fast and idles smooth at just over 1000RPM... but then after about a minute every time, the AFR shoots up very suddenly and it just dies abruptly. I data logged a start-die run and found that right before it dies, my fuel pulsewidth and duty cycle go to 0 for a split second. I have no idea what it could be caused from. I thought it could be my overrun fuel cut kicking in accidently, but I upped the RPM to 2000 and it still happened. I don't have overboost enabled.

What else could cause a split-second fuel cut?

I've attached a couple logs of this happening, just bring up PW and you can see what I'm talking about.
On "2012-05-01_14.28.44" it happens at 87.551s
On "2012-05-01_15.08.08" it happens at 226.535s

 

Have you enabled overrun fuel cut? Try disabling it? Are you losing sync?

 

I did have over run fuel cut enabled. I'll try disabling today.
As far as I can see, I'm not losing sync. Yesterday earlier on in the day I was losing sync with code 17 I beleive (not receiving second trigger when expected), but after adjusting my pots on the board I haven't lost sync since other than after the engine stops of course.

 

My guess here is that your overrun fuel cut settings are causing fuel to cut when you don't want it to.

My recommendation as always is to leave all of the extra features disabled until you have the engine tuned... so turn off all closed-loop features, turn off things like idle advance, idle VE, overrun fuel cut, etc.

Ken

 

Ok so I turned off overrun cut, and I'm not stalling randomly now! thanks!

My sync loss reason 17 is back though, you'd probably be just the guy to ask Ken. If I'm not getting my second trigger when expected (err 17), do the pots on the main board actually help me? Or do the pots only adjust the main VR sensor and I would have to play around with resistors on my separate second VR circuit?

Obviously anyone else can answer that question too if they know the answer :P

 

Usually that sync error indicates noise on the VR inputs or ground problems, or that you have the polarity on one of the VR inputs wrong.

All of the potentiometers should be set fully counter clockwise. IF they are, do a sync error log and post it... that'll capture the actual signals at the time that the error occurs.

Ken