Advice: Overboosting...

[markrichards]

Gents, advice appreciated.

I went to the Easytrack day at Bedford on Saturday. Car ran well for four 20 min stints. On the fourth run I started to hear a squeal/screech under load although with no noticeable drop in power. On further inspection the boost gauge shows boost reaching 1.5bar (should be 1.1 max post a re-map) and then dropping off rapidly. It can't sustain 1.1bar as previously.

Is it a dodgy actuator or split pipe to/from turbo? Some ticking noise from front of engine, which I don't expect is manifolds or gaskets as they have all been carefully replaced recently.

Will drop it at the garage tomorrow but would be keen to give them some guidance as I don't have time to drop at the specialists.

Any help much appreciated.

[RobP]

If you have a standard M400 then 1.5bar is way to high. Where did you have it mapped? Also it won't be split hoses, if you had these then you would have no boost at all. Which garage are you taking it to tomorrow?

[andygtt]

check the hoses to the actuators are not split or have come off

[markrichards]

Thanks both.

Agree that 1.5bar is too high. It was re-mapped to max at c.1.1bar. Garage are a good honest local joint who have worked on the car before. Trust them for small jobs.

Andy, will check the hose to the front actuator.

[XLRONYX]

Interesting that you now have a ticking noise. Back in the middle of summer, I had a momentary overboost that caused a massive backfire. Now I have a constant ticking from somewhere deep in the engine. Because it sounded like mis-adjusted valve lash, I replaced all 24 rockers and hydraulic adjusters, but that made no difference. To my ears the sound is too delicate to be a spun bearing shell. The good news is that it has no gotten any worse in about 500 miles of careful driving.

A new engine is being assembled. I should know the ticking source before winter's end.

Jeff

[Gadgeroonie]

sounds like you have a pipe loose somewhere

is the exhaust manifold now leaking - is the noise worse when cold ?

a session on a rolling road should find the problem for you

[markrichards]

Gadgeroonie said:

sounds like you have a pipe loose somewhere

is the exhaust manifold now leaking - is the noise worse when cold ?

a session on a rolling road should find the problem for you

I'm hoping it's a pipe. I had a new exhaust and manifolds installed recently. The front manifold was installed twice and was carefully checked the second time. The noise is similar to a manifold leak but much quieter. The squeal is not the manifold and a different type of noise entirely. What's unusual is that it seems to have improved overnight and therefore could be a heat issue.

[andygtt]

When my car started ticking it sounded exactly like a tappet... Listened hard and noise was from top end.
Replaced all tappets chains guides the lot before stripping it out and finding it was main bearings :-(

That's when I started modding the car lol