bad wastegate diaphram symptoms

[brian]

I know the proper forum is probably turbos and related, but was looking for the most input.

Went to the track today. First outing of the year, and the wastegate on the THDP is stuck. No biggie, got that resolved. Go out for second pass, car gets to 12-15 psi, and backfires. All other passes were the same result. 6 total. The gate moves effortlessly after a thorough dosing of WD-40, and anti seize.
Now, the wastegate had been cranked hard for years (very tight), and the rod had a slight bend in it. The car always runs racegas and was set up for the track. It seems like the car gets a lot boost, or a spike and lean pops. That is my guess. Part throttle driveability to diagnose the problem is not an option as the car has always had a bout with compressor surge.
This problem occurs when the car is doing a burnout, staging on the transbrake, and going down the track, weather feathered or floored.
The car has all the boost and vacuum lines intact, new plugs and 02, and a full visual inspection. Fuel pressure is good. Seems boost/wastegate related.

Any help is appreciated.
Thank you, Brian

 

[Quick6'n'-K.C.]

THDP, so it internal

You POSITIVE its THDP, not a ATR pipe?
They look identical, the ATR is 1.50 puck.
WD40 spells atr pipe, the actual bushing for the swing arm is mild steel, the arm will stick.

Let start there, then work on the rich pop/lean pop later.

I have had this issue before.
BW

 

[Turboundertaker]

My GN did the same thing went 45 to 48 psi fuel pressure with vac line off. Good Luck! Hated driving mine if it wouldn't go WFO!

 

[brian]

It is definatly a THDP, not ATR.

Brian

 

[Quick6'n'-K.C.]

What part are you spraying with wd-40?
The swing arm on the downpipe or the wastegate rod in side the wastegate actuator?
I have never heard of a THDP that the arm sticks, just the internal ATR pipe.

Just wondering.

BW