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The mkiv Supra Owners Club

Supra has started overboosting...


Kev_A

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My car...

 

'96 TT auto BPU

 

Blitz Nur spec R with double de-cat and (afaik) 1.2 bar RR (Exhaust was on car when I got it)

 

HKS SSQV

 

FMIC

 

BMC CDA

 

Greddy Profec B EBC

 

The car has always boosted fine and I've never had the boost set above 1 bar as I haven't fitted an FCD yet (I do have one ready to go on)

 

Car's been off the road most of the winter but after I had the car M.O.T'd a few weeks back on the drive home I booted it and it made 1.5 bar! :blink:

 

At first I thought some spanner monkey had been playing with my EBC but when I got home and checked all was well.

 

I've since turned down all the settings and even tried turning it off but to no avail, it still overboosts.

 

Any ideas?

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I'm really not too sure mate, again, the exhaust was on the car when I got it, maybe I need to check this, where in the exhaust should it be located? Any recomendations for a replacement if this is the problem?

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People put them in different places mate. Some between the 1st/2nd decat, some after the 2nd decat. You should be able to see it between the joins though.

 

A restrictor ring from CW or Whifbitz is a safe bet :)

 

Also be worth checking all the pipework for the boost controller to check that is all ok.

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Thanks for the advice :) 1st thing tommorow I'll check the pipes from the solenoid and I'll get under the car and check the RR.

 

Nigel as Scott M said, 1.5 bar is way out of the efficiency range for Stock J-spec turbo's, it reached that boost for a split second before I let off, was so quick fuel cut didn't have a chance to cut in!

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First thing to check would be the boost controller hose connected onto the 1st turbo at the front of the engine (wastegate actuator). If it has disconnected it won't control the boost pressure and you will get spikes.

 

Other than that I can't be sure of how to check the wastegate as it is internal with the TT's. Manually pushing and pulling the actuators should let you know if they are ok. Just check them all. I've had one of them sticking leading to me losing pressure but never gaining it.

Edited by Scott (see edit history)
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i was over boosting up as far as 1.71bar not sure if its a combination of cold weather and octane boosters and toulene/xylene, since i stopped adding the additives its come back to 1.4/1.5 bar. was wondering the car was mapped in a hot summer 25deg can the map adjust to when its down to 5 deg say. i really feel that the cold er weather really does give a power surge

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Seen as it has been boosting fine before you took it off the road it could be any of the above. Restrictor ring fell to peices (Dom special - cardboard or something) EBC tubes to check again. wastegate vsv?? wastegate actuator, boost controller solenoid foobared and stuck closed, split pipe(s) I'll see if I have some spare time to take a peek.

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Seen as it has been boosting fine before you took it off the road it could be any of the above. Restrictor ring fell to peices (Dom special - cardboard or something) EBC tubes to check again. wastegate vsv?? wastegate actuator, boost controller solenoid foobared and stuck closed, split pipe(s) I'll see if I have some spare time to take a peek.

 

Cheers dude, I'd appreciate that :)

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