what are symptoms of a bad stock wastegate actuator diaphram?

[brian]

I posted in tech, but it got off topic.
Will a bad actuator put the car into a overboost situation?

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

 

[salvageV6]

To check a bone stock spring wastegate actuator I would put regulated compressed shop air directly into it's port.

No orifices etc. just regulated air via direct hose that you can dial pressure from 5 to 15psi. most compressors will do that.

Should start to move the arm on the actuator at 9psi. this would be with the arm off of any wastegate puck as well just free air and watch it closely for movement.

Should be fully extended at 13/14psi. shop air.

No hissing or leaks obviously.

If you can't see well for some reason put a white piece of paper tied behind the arm and mark the position then use the air and watch the arm in relation to that mark on the fixed paper.

Easy to check off the car.

 

[T. Bell]

Let me know if you diagnose it. I think I have the same issue. I seem OK when I am moving and build up boost, but if I go hard from a stop or a slow roll, then I start popping and missing terriblly. I thought I had an spark problem, but have had not made improvement swapping parts.

 

[motordoctor40]

i had the same problem wit my t type riv and i was the plug wires you must use real good wires pirial core

 

[brian]

Salvage...
Thanks for the info.
I will try the air check.

Brian