zhastaph

Hi, following on from another thread it seems my MY99 Type RA STi is boosting too high. At least 18.6 psi according to the SECS.

The reason I says at least is cos I understand that the SECS clips at 18.4 psi, though it has definately shown 18.6

Tonight I reset the peak values in the SECS, brought her home and quite easily got the new peak up to 17 psi. I then found if I kept sustained high(ish) revs in 4th then floored it she peaked at 18.3 psi and big red on the KL gave a quick flash at the very same time

She's never hit fuel cut since I've had her (bout 2/3 weeks). KL activity is generally very quiet, at worst I've seen the very occasionally amber or red, I'm guessing that these come in when she hits this high boost.


To my knowledge the car is totally standard other than a full decat and I haven't noticed a Dawes nor a bleed valve. I believe the car was imported new, so given that she's run on OB have no reason to suspect that she's been remapped.

Tomorrow when there's some light, I'll have a good look under the bonnet, just doulbe check there's no manual boost altering devices. Next I'll clean the boost solenoid, I guess if this was 'leaking' then technically boost will go very high, though if this was the case then I'd expect to see fuel cut.

I understand having a decat downpipe fitted to these things can cause boost spikes, but to this degree? And it very easily hit 17 psi on only very light throttle (but high revs).


Any other suggestions for what to look for would be greatly appreciated?

sg72

See youve got the right monitoing parts fitted Zhastaph .

Boost should be @1.1 bar (16psi) on you car.
Check for splits in solenoid/Turbo pipework
Should get car remapped with decat.
What OB you using?

Steve

zhastaph

Millers. Seems to do the job at only 3 quid a bottle

sg72

Not doing the job if your getting Big Red!

However, seems your over boosting.So check for splits. Get it mapped and run NF.OB.

You can get it mapped to run UK fuel, if you want.@£600.

Means No OB. Less power. It's upto you

zhastaph

Big red is rare, even amber'srare, normally under very heavy driving I get 2 greens. However tonight, I woz investigating what boost pressure she's running at, managed to get her to peak at 18.3 psi, and at that exact time big red lit up. Not really to be unexpected at that sorta pressure.

But yeah, I think you're right, defo overboosting and probably casued by a leak or somethin.

zhastaph

Ok, I've checked and cleaned the boost solenoid.

I've also check all the hoses from the turbo to the boost solenoid and to the wastegate actuator, no leaks no blockages.

I've checked the wastegate, (by hand with a spanner wedged against the back of the turbo), which opens fine.

I also tried disconnecting the BCS theorising that she should then peak at around 7psi (as pressure will then be controlled by the wastegate only), at least it would prove the wastegate is doing it's job. This resulted in a CEL and then fuel cut when I tried flooring it. I may attempt this experiment again, but by carefully clamping the hose instead with a pair of forceps.



So what next?

Is this really just caused by the decat? If so I assume a manual boost controller like the Dawes will stop this?

Suggestions gratefully appreciated.



Just wanted to add, if there's anyone that hasn't experience fuel cut in their scoob, it's somethin I suggest you try, it's quite an eye opener , though I think the bruise on my forehead may last a few days to remind me of it

dowser

How did you disconnect the solenoid? If it was the electrical connector then this should result in ~7psi...if it didn't, it's not hosed up correctly

Richard

zhastaph

I disconnected it at the electrical connector. Somehow the ECU knew about it though and threw up the CEL. The highest I managed to get out of it after that was 4.7psi. That was when it hit me somewhat nicely with the fuel cut.