I have mate that owns a MY00 uk car with

VF35 (lead to believe boosting to 22psi)
Uprated panel filter
3 port boost solenoid
parallel fuel rails
Full decat exhaust
walbro fuel pump
Mapped to suit

He had a head gasket go, so got them replaced and the car drove fine for a week and a half then started getting boost problems. took intercooer pipe off and found lots of oil. Turbo was fine but head gasket had failed again! got them replaced, but the boost problem was still there. It doesn't feel as as liveley as before, hesitant just before coming on boost, and doesn't boost as hard as it use to. no CEL codes are stored, and had the lambda,maf and fuel pres reg replaced from a another car that was running ok, reset ECU by removing the battery and ran fine. But after a few runs it reverts back to reluctant boost, hesitation ect. He's at a loss to which direction to go now, as everything seems fine just after ecu reset, but the goes down hill from there

he's also had new plugs and the cambelt changed on the fierst head gasket change

 

Does engine temp make any difference?
Were the heads skimmed when the gaskets were done?
Try the boost solenoid clean procedure.
Can you be a little more desciptive with boost problem? Sorry I know it's not your car so it's hard to describe but more info would be grand.

 

he's done the boost solenoid procedure (green plugs connected etc). It stutters a bit before you feel the boost kick in, and when it does, he says its a bit lathargic, foot right to the floor in 3rd and it felt like it was in 5th building up boost!!

 

Is there a boost gauge fitted?

 

it doesn't work any more. when it was working he said it went up to 22 psi (1.5bar). but now it only goes to 1.2bar. (i used a laptop and software to to do some logging)

 

if the head gasket went mate and the heads were skimmed what head set was used because it could have changed the compression ratio?

 

i did think of that, but he did say though they had only the lightest of skimming. not sure of the head set though. could this have made that a bigger difference

 

Surely if the ecu reset cures it temperarily it cant be mechanical. That why I asked earlier if engine temp makes a difference! Reset the ecu by connecting the plugs instead of disconnecting the battery this way you'll keep the heat in the engine. Plus doesn't it give you 'live' faults instead of historic codes.

 

i think if you have a live code, the CEL stays on. not sure about engine temp yet, could be a cause? how would I check this? I can connect to the ecu, so would it give an unusual temp reading or do they go faulty a different way

 

I ask about engine temp, as you can't rule out an issue with the work that's been carried out. Logic says it something due to the head gasket failure. If it only hesitates when hot is what I'm trying to work out. What sensors have you looked at on data logger? Maf, lambda, map,

 

spoken to the guy who owns the car, and it ran fine after head skimming, so it's unlikely its compression. lambda voltage reacts the way it should, Maf voltage has no unusual spikes and follows the similar curve to TPS voltage and engine speed, not sure about boost curve with it being mappedc as tis may be different.

I know internet diagnosis is hard, but just looking for different ideas to see if anybody comes up with something different

I know splitpin comes up with good suggestions, as he helped me with mine (although i haven't managed to cure it yet.lol)

 

bttt

 

BTTT

 

anymore suggestions?