Surging at full throttle not 3/4????

[25pounds]

I would like some input on what my problem might be caused by. First of all here is what the car is 86 GN engine/trans, stock engine except for 36 lb injectors 868's, Reds 108 race chip, K&N cone, slightly larger cam. Full tank of 110 octane (about 8 months old). Fuel supply is a single Bosch 286. The problem i am having is a hesitation/stumble at high boost/high RPM/ full throttle sometimes even poping. It seems too that as you ease off of the throttle the car almost lunges forward like it wants to run better at 3/4 throttle. TPS is set correctly, coil pack & module have been tested, fuel pressure is holding steady at 70-73 PSI under 19-22 PSI boost. I am using a Scanmaster & seeing some knock (eratic 10degrees then nothing) and my O2 MV are eratic as well but usually looking good under full throttle.
Possible probs:
Wastegate solenoid? 16 PSi 1st gear then 20-22 in 2,3.
Bad chip?
Bad gas?
Why does it seem to run better as I ease off the gas?

Thanks, Ryan

 

[TURBOV6]

Whats your MAF reading? It should be around 5-6, if not you got a bad MAF.

 

[gnxis]

how many miles on motor? valve springs

 

[Quickturbosix]

I had the same problem...Cam sensor wasn't set right.
But..
The above items need to be checked too.

 

[25pounds]

Thanks for the help. I have a cam sensor tool and have checked it=OK. I will check the MAF though that could be it because I purchased this one used about 5 years ago. Is that MAF reading at idle? or WOT? The engine has about 5K on it with fresh heads & NEW springs. Any other ideas are welcome before I can get the MAF checked.

Thanks, Ryan

 

[azgn]

you are running 50 lbs of static fuel pressure?? (20+50=70lbs!)

I think Red likes 42 or so on his chips

could be your fuel pump is taking a dump at that pressure

 

[UNGN]

Originally posted by 25pounds
Is that MAF reading at idle? or WOT?

5 at idle, 255 at WOT.

 

[elevensecgn]

The old gas could have gone bad. Are you monitoring the fuel pressure with a visible gauge while at wot?

Whatever it is get it fixed soon or stay out of the boost till you can figure it out. It can get deep into your pockets if it detonates much.

Dwight Hayden

 

[25pounds]

Yes that pressure seems a little high, but it was not running as good at the lower press (42-45) but I will try dropping it again to see. I think I will get that gas out of there also.

 

[1BADT]

I had the same trouble last summer. For me it turned out to be a loose intercooler hose that was bleeding off boost at WOT... It's a longshot but give it a check. GOOD LUCK

 

[azgn]

do what Dwight said.....check the fuel pressure under boost...if it runs better with the higher static pressure, either your pump can't handle the volume or the gas is bad or both!