Overboost? Rough acceleration? It may not be the wastegate..

[Jackonicko]

I've suffered boost creep, overboost and roughness on acceleration for some time.

There was never a fault code on the CEL.

I changed:

Plugs
Leads
Coil packs
HAS

Specky kindly did the full wastegate wiggle. Elanscan showed only that the idle was very irregular and the spark advance was all over the place.

Nothing cured it.

Gerald at GST looked at it with a timing light and said that there was:
“a lot of scatter, even though the CAS is fully advanced.”

There seemed to be two possible causes:

1) The cams or cambelt are slightly out (eg that the alignment between the inlet and outlet cams might be just out perhaps because one of the cams has rotated slightly when the belt was put on) but that this was compensated for (to some extent) on the CAS.

or

2) That the CAS was loose and wobbly internally, with some ‘radial’ play.

I picked up a new, unused CAS at Donny, and it was fitted (and the base timing reset) today. The car is transformed.

The 'spline' on the old one (the rotating bit at the bottom of this pic) was visibly bent.

[esprit888]

How many miles on the engine to cause this type of wear?

[Jackonicko]

Looked more like damage than wear, Esprit.

(I'm on a tad over 120k miles)

[Jackonicko]

When I say bent.....

[HJ2]

WTF???

How did THIS happen?
That's a nice flat O-seal by the way

[Jackonicko]

I don't know how it happened.

I do know that a lot of experts saw the symptoms and did not diagnose it.

I do know that my car's performance has been transformed. (And that feels like such an under-statement.....)

I do know that overboost has been cured at a stroke.

I do know that the idle is now boringly even.

[Specky]

I know what's happened...

School boy error...

Who ever has put the CAS in place didn't engage the drive and then went and torqued it down,(This must of took some doing)... anyway... it bends the drive

TTFN

[Jackonicko]

The difference is staggering, Speckers, you must drive the car again soon.

I have the fag lighter (it may not work, but it's yours).

The car was previously looked after by some outfit in Filton. The CAS hasn't been touched since I've had the car.

After reading about the difference that worn bearings in the CAS can make, and then experiencing this, I do wonder whether this isn't a common, undiagnosed fault.

You know how the car overboosted Specky, but I've been scaring myself shitless (driving like you, only on speed) trying to provoke an overboost and haven't been able to.