J-J-J-J-udder with Forge re-circ....
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Scooby Regular
Joined: Jul 1999
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Just fitted a Forge re-circ dumpvalve. Running an HKS FMIC. Improved over std BOV except...when in 4th or 5 th gear; if you tip-in on the throttle, then as you are accelerating you lift off the throttle gently, when you get to the `balance` point and the dump valve cracks I get a J-J-Juddery release of boost pressure.
Will a spring change sort it or a change of driving style?!!!!
Full throttle, quick throttle lifts no problem, infact it is only the slow back-out from the throttle that does it........any ideas? This is also what the OEM one did, only it was much worse!
Will a spring change sort it or a change of driving style?!!!!
Full throttle, quick throttle lifts no problem, infact it is only the slow back-out from the throttle that does it........any ideas? This is also what the OEM one did, only it was much worse!
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Joined: May 2001
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James - have a look at the spring. I had a very similar situation with mine when it was first fitted. I had the blue spring in mine, which apparently is best suited to the VTA, and you need the red one to be fitted. Once I changed this the problem went. 
If you've got a blue one, simply phone up Forge and they will ship out a replacement spring. The turn around time from Forge, was simply superb, as the replacement spring was with me the next day, all FOC.
If you've got a blue one, simply phone up Forge and they will ship out a replacement spring. The turn around time from Forge, was simply superb, as the replacement spring was with me the next day, all FOC.
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Joined: Nov 2000
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From: 32 cylinders and many cats
James, mine did the same quite severely with the blue spring and MD304 - really obvious and horrible after the FMIC.
Red spring virtually cures it, still a little shudder on very light lift off, but not much worse than the OEM one.
Just watch if you compressor wheel is up to the job of the red spring which is quite a lot stronger.
Shimming it would be an easy way to test. Forge are not too keen to send out springs unless you explain to them the problem. After that they sent me a weaker spring which they were sure would sort the problem, but as Bob suggested the stronger red spring was right for my setup.
Red spring virtually cures it, still a little shudder on very light lift off, but not much worse than the OEM one.
Just watch if you compressor wheel is up to the job of the red spring which is quite a lot stronger.
Shimming it would be an easy way to test. Forge are not too keen to send out springs unless you explain to them the problem. After that they sent me a weaker spring which they were sure would sort the problem, but as Bob suggested the stronger red spring was right for my setup.
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