Hey guys,
first of all I apologise if this has been covered already but I'm not sure where to look so ill ask here!

I'm not new to performance work but I am new to these engines. Ive done lots of work before but only to the LS motors - but I have now converted to an xr6t.

Basically, I have an MKII BA Xr6t.
180xxx kms.
I bought it from a dealer about a week ago but ive just noticed that it has what appears to be a boost spike under heavy load. I was told its running 10 psi so I wired up a boost gauge and that seems to be correct but as soon as it hits 9-10psi it spikes to 15 (approx.) and has a misfire/splutter.

to drive it normally it is perfect, this only happens under heavy load on boost.

Could this be the ignition coils, boost leak?

what do you guys suggest I look at? as ive said ive done lots of engine work before but these barra turbo engines are new to me!

Thanks guys...

does it have any aftermarket goodies like an exhaust or high flow cat? exhaust mods or exhaust leaks can cause boost spikes. check all the dump pipe exhaust manifold are tight.

It does have an exhaust, come to think of it I think there might be a slight leak. I didn't think that would cause it but I'll certainly look in to that tonight. Thanks mate!!

Any other ideas would be much appreciated too!

if the aftermarket exhaust is to blame you would be best to get the internal watesgate ported with a larger flapper or swtich to an external gate.

Take it back to the dealer and make them fix it.

It's out of statutory warranty. I work in car sales so I know I've got no where to go as far as a warranty or getting them to fix it.
I actually put a few hrs into it today and still can't find the fault. Checked all boost/vacuum lines and fitted new coils in hope it was that and still no improvement.

I'll most likely have to leave it for a month or so and take it to a tuner to look at it when I get some work done.

Frustrating at the moment!

have you had the car scanned for fault codes?

is it the stock actuator on the turbo or a aftermarket one?

Guessing it dont boost spike under light throttle and load?

Was the car ever tuned to run 10psi? stock tune on these was 4-6 psi from memory, and anything over 10 i'm under the impression the PCM went into a LHM mode to save engine damage.

sounds to me like its not getting the exhaust gas out the back quick enough, as bry40l said



i would also get the tune checked to make sure its tuned properly