Tech/Tuner help needed !!!

[88YotaTurbo]

I am running an 88 supra turbo with greddy intake, Hks SSQV BOV, 3" turbo back exhaust without a cat. I have been experiencing my fuel cut at 15 psi. I'm looking for a way to lower my psi without my silencer so I no longer hit fuel cut. I know I can buy a fuel controller or do the lex/550 mod. But I'm looking for something cheaper. Please help I am soon to autocross my car and I would love to use it without my silencer. Thank you for your time.

 

[GrimJack]

Are you using any kind of boost controller? Are you still using the stock AFM? How did you get your boost up to 15psi?

 

[88YotaTurbo]

no boost controller. Stock AFM. it is boosting to 15 psi all by itself without a boostcontroller or upgrades.

 

[88YotaTurbo]

anyone have any answers?

 

[snotboy]

is your wastegate shimmed?

 

[88YotaTurbo]

I checked today because that is what I first thought and it turns out it was not shimmed. I also checked my piping and didn't notice any cracks for boost leaks.

 

[jdub]

What are you using to measure boost psi?

 

[chevyeater]

Wastegate stuck shut?

That Duane's car in your car club picture? He could definitely help you out if you know him...

 

[88YotaTurbo]

I'm using an Autometer mechanical Phantom 30-30 guage. maybe it is stuck shut????? could it be anything else?? can I limit boost via bov.??

 

[Supracentral]

I'm using an Autometer mechanical Phantom 30-30 guage. maybe it is stuck shut????? could it be anything else?? can I limit boost via bov.??

Negative - wastegate is really the only way. The WG vents exhuast. The BOV (if you could find a way to make it leak) would just vent air that your ECU had already added fuel for - you'd wind up hitting cut even earlier.

Try removing the two bolts that hold the wastegate acutator on so you can see if the wastegate flapper moves freely. If it doesn't the problem is inside the turbo. If it does, I'd start suspecting that the actuator may have a blown diaphram.

 

[88YotaTurbo]

Thank you very much. I'll check on that tomorrow and get back to you. If it isn't the wastegate then what else can it be?

 

[Supracentral]

Thank you very much. I'll check on that tomorrow and get back to you. If it isn't the wastegate then what else can it be?

Make sure the little hose that goes from the compressor housing to the WG actuator is intact.

Other than that, nothing I believe.

 

[bigboost7m]

Make sure the little hose that goes from the compressor housing to the WG actuator is intact.

Other than that, nothing I believe.

And make sure that hose isnt pinched, as you could hit max boost levels on the stock turbo and end up overspining it.

 

[88YotaTurbo]

ok will do and get back to you all. Thank you for all your helps o far.

 

[88YotaTurbo]

ok I check the hose running from the compressor housing to the actuater it is intact and not kinked. Then I loosend the two bolts that hold the actuater in place and it feels like a hard spring is inside the actuater. I tried to pulling on it toward the front of the car and it is quit a hard spring. i had to struggle a little bit to compress it. I'm not to certain what to look for but it seems as if everything is working properly.
However I am still boosting to 15 psi and hitting fuel cut.

 

[jdub]

Does the wastegate arm on the turbine housing move freely?

Test the actuator. Take the actuator off, use an air compressor (set the regulator to 7.5 psi) and blow air into the actuator through the hose...use a tip so it will seal on the air compressor side. If the actuator doesn't move, it's bad. Here's what the TRSM says:

http://www.cygnusx1.net/supra/library/TSRM/tc/TC_08.html

 

[88YotaTurbo]

ty for the clearification. I'll test it and let you know.

 

[tubbie]

Could just be your boost gauge is bad....... Barrow one to see if it does the same thing......

 

[jdub]

Could just be your boost gauge is bad....... Barrow one to see if it does the same thing......

Yeah...thought that too earlier. But if he's hitting fuel cut, likely it's fairly accurate.

 

[88YotaTurbo]

I am hitting fuel cut. I'll describe it to you. driving hard almost wot say like 95% throttle. High rpms say 5,500 boost gauge climbs to 13, 14, 15 sudden violent jerk and CEL. Read the code and it's for turbocharger pressure or something. code 34 i think???