Hesitating at full throttle ?

[Thrumbleux]

I agree. Do you mean a cylinder leakage test ?

No, just read then for colour looking for signs of a rich or weak mix on one or more cylinders.


[QUOTE=marcjero;n879646What is strange is this happening after a 15 minutes drive. The engine is running very well until the problem start.[/QUOTE]

Implies a temp problem - over-fuelling, or some electrical/electronic component fading with temp..Would have thought though that an over-fuelling problem would manifest itself sooner than 15 mins - but then there's the glowing cat....

[Buckster]

You have checked for leaks between the the turbo manifold and the exhaust haven’t you?

[tolsen]

Please remove all plugs and post photos of their business end. Make sure to mark them so you know where they came from.

[marcjero]

I agree. Do you mean a cylinder leakage test ? What is strange is this happening after a 15 minutes drive. The engine is running very well until the problem start.

[Thrumbleux]

Hi,

I changed the crankshatft postion sensor but the problem is still here. It takes more time to appear though. Maybe because the weather is cooler now. I also noticed that the intercooler fan is not working anymore. Does a failing intercooler fan could lead to misfire problems ?

Wouldn't have thought so though the ECU will pick up higher IAT and make some compensation. Try hot wiring the IC fan to eliminate as suspect. Anyway, at speed, I'd guess (cooling) airflow through the IC is mainly from the scoop.
Time to pull the plugs and look for a specific cylinder being the cause?

[marcjero]

Hi,

I changed the crankshatft postion sensor but the problem is still here. It takes more time to appear though. Maybe because the weather is cooler now. I also noticed that the intercooler fan is not working anymore. Does a failing intercooler fan could lead to misfire problems ?

[marcjero]

Yes earths are fine. I don't think it's overfueling else it should smell bad. Fuel trims are close to 0. Could be an ecu issue ?

[Thrumbleux]

Coils powered from ECU as far as I know.
Are all the electrical earths OK? (coils especially).
If not ignition related, then possibly massive overfuelling but hard to think of a cause.

[marcjero]

Hello,
we ran a test at night. There is no spark from ht leads. But we noticed the cat became red. So I guess the problem is about ignition and fuel is burnt into the cat. HT leads seem to be ok. Is there a power supply module for ignition coils ? I don"t think 3 coils can fail at the same time.

[marcjero]

No EML on. No ECU error code so far.

[Thrumbleux]

BTW, when mine burned exhaust valves and was misfiring (completely non firing) on cyl # 1, the EML lit up. Not suggesting you have anything as serious, but a prominent misfire will invoke the EML.

[Thrumbleux]

Give that a shot just to eliminate it as a possibility. If the plug leads have been removed without the correct tool (or badly with the correct tool!) they could be damaged. Coil packs have been known to fail also. Getting to them is a bit cramped as they're hidden under the inlet manifold.

Might be worth pulling the plugs for a reading to see if there's any clues there.

[marcjero]

Thanks so the next test will be to look for sparks at night

[Thrumbleux]

. And I don't see the link between load (boost) and the crank position sensor.

Right enough, no real link. CPS is really only telling the ECU where the crank is at - for both ignition and fuelling purposes - and is pretty digital. Missing under load is usually ignition components failing (typically weak insulation on the HT side) because it is harder to introduce the spark to a cylinder holding high pressure.

Easy cold starting implies there is sufficient fuel flow - at least to begin with. You'll just have to whittle down the list of possible suspects though if the CPS is suspect I'd leave it to worsen a bit and confirm the diagnosis before diving in to change it. They can be a right PITA to remove.

[marcjero]

Yes maybe. The point is that engine startup is no problem warm or cold. Moreover reving under light load is not problem also. And I don't see the link between load (boost) and the crank position sensor.