Author Topic: Legacy B4 secondary boost at 5-6k rpm..  (Read 1722 times)

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Offline Valkyrie

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Legacy B4 secondary boost at 5-6k rpm..
« on: May 05, 2016, 01:07:06 pm »
Not my car bit helping a friend troubleshoot an issue with his legacy B4, and having a great time learning about sequential turbo setup thay subaru has designed

In a nutshell, symptoms are the code 66 (which now only shows up intermittently after cleaning out the solenoid box, he says it flashes on when he gives it the beans but then it goes away after.) but secondary turbo doesn't seem to be making boost till between 5 and 6k rpm. Hits about 7 psi for normal pull then... nothing till much later on in the rpm range. My initial thought was the air intake control valve wasn't opening until the turbo was forcing it open at a much later rpm. Now I'm thinking the exhaust control valve may be stuck open. Anyone have any similar experience on this type of issue?

One thing I did notice was the line #1 to the air intake control valve actuator seemed to have excess pressure in it when I removed it from the solenoid box with the car off. Is this normal? Isn't the valve actuator controlled by negative pressure?

Any bit of help/knowledge appreciated, cheers.

Offline Valkyrie

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Re: Legacy B4 secondary boost at 5-6k rpm..
« Reply #1 on: May 06, 2016, 04:46:36 am »
Issue solved. Sorry for posting in wrong section.

Offline piggy

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Re: Legacy B4 secondary boost at 5-6k rpm..
« Reply #2 on: October 12, 2016, 12:30:20 pm »
I'd be interested in hearing how you solved the problem as my car seems to be running in a similar manner.

Offline Valkyrie

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Re: Legacy B4 secondary boost at 5-6k rpm..
« Reply #3 on: March 29, 2017, 10:36:32 am »
this is how this whole ordeal played out,

Code 66 and had a code 22 as well which i wasnt aware of until he re scanned. So we cleaned the solenoid box, changed primary and secondary turbos and replaced the ICV and ECV. tested both valves before installation. Basically the primary was garbage, both were which was why there was no initial boost untill secondary kicked in. Also after finding the code 22 (knock sensor crapped), nothing we had done before would have shown as fixed cause the car was stuck in limp mode.

SO.. if boost only hits 7 psi at 6k means primary TC is dead. Issue was solved by converting to a single turbo setup and deleting the sequential completely.