odd issues in my 94 2500 light duty2wd

[vstech]

I reported this last year, but didn't follow up on it... sorry.

any way, the truck runs great at city speeds, and some on the highway, but if I need full throttle for a hill or if I'm towing anything, the turbo builds pressure up around 15psi for a second, then ALL boost drops to zero and I have little power.

I'll also get a service engine soon light, (36 I think... I'll dig into that soon) that will come on until I drop the throttle back, and then it goes out, and the boost is back until I punch it again...

if I keep the throttle down, the boost never returns. if I feather the trottle and slow down climbing the hill, the boost stays below 10, and I don't have any issues... but if I try to accelerate, or hold speed, the boost crests 11, and then dumps.

this does NOT affect my cruise control. if I'm on cruise, and it climbs the hill, the boost climbs, peaks, and dumps, but the cruise keeps trying to hold speed...

 

[vstech]

here are the codes...

 

[btfarm]

Looks like a spring loaded wastegate is in order. And no, I don't know the specifics of that but several others will...

 

[Twisted Steel Performance]

If you still have the flat panel filter, that is the culprit, if you want to test my theory, remove the filter and mash your motor, if it doesn't stall out there is your answer....

 

[NVW]

If you are running a stock tune, boost over 10-12 psi will put you into limp mode. Somewhere in that range anyway.

To get 15 psi are you already using a mechanical wastegate?

 

[vstech]

nope, I'm stock. nothing changed but the intake manifold... and the exhaust is upgraded to diamond eye.
if I punch it climbing a hill, the boost jumps to 15psi, then drops to zero, and stays there until I let off the throttle... if I feather the throttle up a hill, and keep the boost below 10, there is no issue... except I get only the acceleration I feather in...

I'd think limp mode would limit fuel too, NO? from the CLOUDS of black smoke, I'm certain fuel is not being limited... just the boost...

I don't think the filter could cause boost to drop to zero instantly. sure, it could limit boost, but not cause an instant drop.

 

[Twisted Steel Performance]

I don't think the filter could cause boost to drop to zero instantly. sure, it could limit boost, but not cause an instant drop.

Well, mine would with my setup easy and instant and bellows of black.....

Have you tried removing the filter for one trip up the hill, why don't you prove me wrong and give it a try....I don't mind being wrong....

 

[uniquediesel]

Plugged vacuum line, blocked vent on the solenoid, or the solenoid is bad.

 

[uniquediesel]

also possible the wastegate arm is binding. With the truck not running and cool, grab the wastegate arm and move it like it would normally be moved, also see how much rocking play it has, it a lot, it could be binding up in a closed position.