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Re: Overboost on cruise control...

Posted: Sun May 31, 2015 10:44 pm
by Doggy
Yes, more or less.....

It's got a variable turbo & no waste gate. The turbo actuator is vacuum operated and needs vacuum to reduce the boost.

The problem will be down to either a vacuum leak, or something limiting the rate the vacuum can be applied to the turbo.
(Mine was a split diaphragm in the swirl actuator, GingerMagic's was a partially blocked vacuum restrictor in one of the vacuum pipe tee-pieces).

Only trick is finding it - since your's only does it climbing a hill, you have a minor leak / restriction.

Re: Overboost on cruise control...

Posted: Mon Jun 01, 2015 6:34 am
by GingerMagic
The restrictor is built into the 'T' piece that clips onto the vac pump, and also on the servo end.

Once you have simplified the vacuum system, you only need a 2 way outlet clip on the vac pump ( 1 to turbo EV, 1 to servo ) which will hopefully make things better.

Do you have access to a hand held vac pump? You can measure the vacuum before and after the EVs to eliminate them as suspects 8)

Re: Overboost on cruise control...

Posted: Mon Jun 01, 2015 12:37 pm
by Doggy
Username Removed wrote:This post has been removed.
:oops:

Re: Overboost on cruise control...

Posted: Mon Jun 01, 2015 4:47 pm
by GingerMagic
I believe if you are overboosting, the wastegate isn't opening fast enough, or not at all - the vacuum reduces the boost by opening the wastegate...

Re: Overboost on cruise control...

Posted: Mon Jun 01, 2015 5:10 pm
by Doggy
One sure way to find out - disconnect / plug the vacuum supply pipe to the turbo/wastegate control valve and CAREFULLY test.
No boost = vacuum need to close wastegate.
Normal/overboost = vacuum needed to open wastegate.

Re: Overboost on cruise control...

Posted: Mon Jun 01, 2015 5:14 pm
by steve_earwig
WHen the mechanics accidentally knocked the vacuum line off the turbo on mine it was a slug, so I guess it needs vacuum to close :?