Misfiring Issue

[TurboTimTam]

Hi guys,

 

I have a bone stock manual 2005 XR6 Turbo Ute, done 97000ks. I'm occasionally getting a "misfire" of sorts when under load in 3rd or 4th gear. It doesn't happen all the time, but when it does, its at about ~4000rpm in 3rd or 4th gear only, happens whether I'm WOT or just cruising up the rpms, seems to be when it's at full boost. When it occurs, the rpms drop instantly back to about 2000-3000 and I have no input with the accelerator. If I try to accelerate it just stays at about 2000ish rpm and the engine sounds like its "out of sync" for lack of a better term. I either have to turn the car off and on again, or put it in neutral (still moving) blip the accelerator a couple times, put in back in a gear and the engine just "gets back in sync" and starts revving normally again. I've searched the forums and have tried a few suggestions. I've had my mechanic replace the intake manifold gasket, spark plugs and coils but it has made no difference. It's hard for a mechanic to diagnose because they test drive it and it's fine or they can't get it to do it so they can only suggest parts to change based off the problem I'm describing. If anyone has any suggestions please let me know. Cheers.

[4321]

Put a boost guage on it & take it for a drive. Should go to 6-7 psi. If it go's over the ecu will see it's over boosting & do exactly that to prevent engine damage. Then get a new actuator fitted if all the hose's are still on 

[TurboTimTam]

Thanks for the suggestion mate that's definitely a possibility. The turbo was replaced 10000ks ago but maybe the actuator was a dud. I'll throw a boost gauge in and check for over-boosting. Cheers.