[thomasv]

My evo 6 (173.xxx kms) drives normally when I drive calm. But when I give it WOT it boosts to 1.3 bar (peak) then starts jolting heavily and boost drops to 0.8 bar. I'm running a evo 8 turbo.

Things I have already changed:
BOV: evo 8 MR fitted
Wastegate actuator: Evo 8 fitted with appropiate preload
Sparkplugs NGK BPR8ES
Fuel Filter

Can anyone tell me what the problem could be?

 

[strange_days_uk]

possibly MAF sensor, or coil pack

 

[grants]

I'm thinking "Boost Cut" where the MAF senses a volume of air greater than that mapped in the ECU
This commonly happens when the ambient temp is low (circa 5 degC) as the air is more dense. A upgraded turbo would also contribute to the issue

Probable solution is a remap

G

 

[grants]

Have you sorted it ?

 

[MikeC]

Just re read your post, won’t be my suggestion.

 

[grants]

And your suggestion is ??

 

[MikeC]

And your suggestion is ??

Sticking actuator causing overboost. The early ones can suffer water ingress and rust, causing them to stick. Re read to see he has a later one fitted and setup.

Good to note for others that the MR ones had a cap to overcome this very issue. The standard 8 ones may have too.

 

[dessimpson]

Sticking actuator causing overboost. The early ones can suffer water ingress and rust, causing them to stick. Re read to see he has a later one fitted and setup.

Good to note for others that the MR ones had a cap to overcome this very issue. The standard 8 ones may have too.

I had a forge actuator on my old 5 that failed after 3 years. Could move it with virtually no effort. Replaced it with one from an 8 (think the 9 ones are different?) and never had an issue again.