Overboost issue intermittent

[TIG ACM]

Having some problems with my 172 cup turbo.

Giving it stick from stationary, through the gears up to 5th the boost is fine, runs and pulls very well. Boosts to 10psi....
Lift off, slow down, accelerate from 3rd and it boosts to 14psi, engine misfires and sounds awful.....
Slow down to 20mph, accelerate from 2nd through the gears boosts to 10psi up to 5th and runs and pulls like a dream.......

Ideas anyone?

 

[Cupman29]

What ecu, boost control general setup do you have? Very hard to diagnose with so little info.

​Who did the mapping? Did it ever work ok?

 

[TIG ACM]

It was a setup that was on another clio and dropped onto mine. Worked fine in the other car...

ECU is a mapped standard one by ktec,
Its a LPT kit from ktec few years ago,
Boost control is a vac acutator linked to the compressor housing.

I know the ecu isnt the greatest but i cant see how this would cause the overboost

 

[mi16chris]

It was a setup that was on another clio and dropped onto mine. Worked fine in the other car...

ECU is a mapped standard one by ktec,
Its a LPT kit from ktec few years ago,
Boost control is a vac acutator linked to the compressor housing.

I know the ecu isnt the greatest but i cant see how this would cause the overboost

Is there any leaks in the vac hose to the actuator , if not I would check ur waste gate is moving free and ur actuator is 100%

 

[TIG ACM]

from what I can see the vac hose looks fine, i am going to take a few bits off tomorrow afternoon to get a better look and look for small leaks/holes.
Had a issue with wastegate yesterday where it jammed fully open. loosened off the down pipe and it free'd up and moves fine again with the downpipe tightened now.
My feeling is that its the actuator, going to speak to turbo technics tomorrow as they are round the corner from our office and see if I can get the actuator tested i think.

 

[Dan@SJM]

You've pretty much answered your own question. Either the wastegate is sticking closed or the actuator.

The misfire your feeling is it running extremely lean.

 

[TIG ACM]

Thanks Dan,
I wanted to check what I thought it might be, I didnt have much mechanical knowledge until about 8 weeks ago when I set about swapping the system over so am still very green. Didnt want to be missing something blindingly obvious.