Engine cut out during heavy throttle, idle ok

[FroMigizims]

93 laser rs turbo
The engine cuts out really bad when throttled, but idles ok (boost/vac wavers around-7).
When free revving it is almost impossible to rev above 4g, on the road very little throttle can be used or engine will cut out (not die).
Multiple tests conducted:
ECM codes, MAF, TPS, spark plugs, wires, Ign module, Injector waveform, all checked OK
Also no visible carbon build up in intake manifold
HELP!! I am a auto mechanic w/10 years under me, and this problem is making me INSANE!

 

[injector]

did you by any chance check your fuel filter?? it could be clogged, we get car all the time that'll idle fine but when you give them gas they hesitate or stall, we found out that the fuel filter was so clogged that when the pressure increased it would completly cut out.

 

[FroMigizims]

Been offline.
I got a new vac/boost gauge with better results: -18 at idle, steady needle.
Plugs, wires, & fuel filter all new.
Fuel pressure: 35psi. idle, 40psi. full throttle.
No vac leaks.
No codes.
Cut out (with considerable misfire) happens at : 0 vac/boost, 4k rpm,more than 1/3 throttle.

 

[injector]

well i had the same problem about a week before my ECU went to hell when i had throttle about 60-70%+ it would loose power just as if i had been loosing spark, then a couple days after my ECU died.

 

[eclipsh]

^^^ Hmm... good point. Yank your ECU apart and see if you have any leakage on it.

Also, your vac looks good but we still don't have compression #'s.

What does your 02 reading look like? If you don't already have one, a Pocketlogger may be your best friend on this...

 

[FroMigizims]

found my problem!!!
bad computer!!!

 

[injector]

i suspected it but i wasn't sure, good luck tho i just got my new one today, putting it in tomorrow

 

[spyder97gs]

Where exactly is the ECU located? Is it behind the radio? I'm getting throttle hesitation once and a great 5 miles at full throttle, and it just started today. I have also been experiencing random power surges it seems. My radar detector will make an odd beep, and my radio flashes.

I'm suspecting it "could" be the ecu but want to investigate further.

 

[injector]

in an N/T with a 420A engine is in the egine bay next to the air filter on the driver side in tubo charged it's behind the radio, when this happened to me my camshaft sensor went bad and then it threw me a code, you might want to check your cam and crank sensors before replacing the ECU.

 

[laserwitpsi]

I own a 90 turbo laser and it is having a lot of problems similar to his but I have checked the ECU, new plugs, wires, done a boost leak test, checked timing, examined the turbo and nothing has solved the problem. There is no check engine light on but when you put it in gear it wants to die unless you give it a lot of gas. The car has no power but I checked the compression and it was 148, 150, 155, 160. I don't think there is a problem with the valves but the spark plugs keep getting fouled out. I was wondering if a problem with the camshaft position sensor could cause this, or maybe the coolant temperature sensor. Any opinions would be appreciated.

 

[injector]

a problem with the cam sensor would feel like temporarily loosing spark, if you want to be sure hook it up to a scanner and have someone else look at the scanner while you drive the car, drive it hard then normal then hard then normal sooner or later it should fail and the scanner will say no signal from cmp or ckp, but a bad cam sensor shouldn't cause a bad idle did you check your idle nut (on my 420A you can adjust a nut on the TB to make it idle higher or lower) you might want to check your IAC too