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Hi all,

Wel affter £250 work to repair a cowboy's work I have fond a nasty niggle with my 93 Aero (non TCS).
I can accelerate hard in any of the first 4 gears but if I put the power down through each gear, revving to about 5K in each, it starts to pull in 5th then almost immediately I get an overboost cut-off effect which at 85-90mph is very off putting. It happens for a split second then appears to be fine, and only in 5th as far as I can tell.

Does anyone know what this could be? I do have the speed warning set at 85mph but surely this is just an alarm. I will try a couple of test runs tomorrow.

Thanks
Lee
 

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I have the same problem with my 9-3 after fitting a Stage 1 (see my topic "Problem under acceleration" in the 9-3 section). Seems to be that base boost has been set too high. I'm going to the garage for a service tomorrow so I'll let you know
 

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Hi
When it hits the overboost, where is the boost gauge registering? Mine will boost well into solid red now in 1/2/3/4 without "overboosting" but I never really floor it in 5th anyway..it gets to 90mph in third so never really felt the need.

You could try filling it up with Optimax and see if it does the same thing.Could possibly be poor fuel causing knock and limiting boost.
Have you done an adaption run as well?

HTH
Ant
 

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Originally posted by HSJrSaab9000:
[qb]I don't understand. How can setting the boost to high cause it to cut out to low? Am I missing some thing?    [/qb][/b]
Because the base boost is too high, there is not enough headroom for a boost spike to occur before hitting the boost limiter.

The apc valve has a delay so boost can rise quicker than the APC can cope. It is even worse if you have a ball bearing turbo which spin is very quickly!!

Andrew
 
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