still hesitating under boost.

[gixxer750]

Its bad...

Feels like fuel cut, but it isn't. I get no code 34, and the afm signal never goes above 1100 hz. Happens at anything over 2 psi of boost, starts hesitating and surging. A/F stays correct, no codes. It was throwing a 52 so I took the entire harness apart and redid the knock sensor wires with high quality sheilded cable, and I made sure to ground the shielding. I swapped out both knock sensors and the code is gone.

Timing is 10deg BTDC. If I neutral rev, at a few different throttle points I get a miss/ hesitation before it will rev.

Any ideas guys? I'm almost to the point of pulling the engine and parting it out

 

[Dr Evil]

Have you checked your fuel pressure regulator and plug gaps / grade ?

 

[malloynx]

how is the health of your ignition system. primary and secondary

 

[mtoxracerfss]

B O O O O O S T L E A K! Check the whole intake tract!

 

[mkiiSupraMan18]

Something made me think fuel pump until I re-read it... but I gues it still may be worth checking. I remember when mine went out it was like someone turned the engine off if I tried to accelerate too hard.

*edit*
I would think that the ecu would throw that silly "turbo press."(or whatever) code if it was bad enough for the car to be missing out like that. (but I've never had the problem, I always blew the hoses clean off) Still something I would have forgot to check

 

[gixxer750]

well, its a fairly new walbro pump, a new afpr, it's NOT a boost leak, as the pipes will hold and maintain 30psi with a boost leak tester

 

[MDCmotorsports]

Gix:
Are you sure the electronics TO the pump are aok and the pump is getting constant 12v?

 

[againstdawall06]

im betting on the ignition.....what are you gaps? how are your wires? plugs? test your coil packs....

 

[gixxer750]

plug gap is at .028 with autolite racing 3923s. I've tried 2 sets of coil packs, and the wires are 2 month old ngk plug wires. I checked the FP voltage, and yes, it is getting 12 volts

 

[IJ.]

Gixx: Knock it down to 25 thou (I had to over 22psi)

 

[bigaaron]

Get a wideband on there, you could be running way lean and not know it. When my stock fpr vacuum line popped of it did what you are describing. It was under the manifold so it was hard to see.