overboosting

pacman7mgte · 03-31-2010, 05:02 AM

i have a 91 turbo supra (automatic transmission ),i need some advice.. my car is drivable, but when i hit the gas to pass someone or just because, the boost needle goes up to 15 psi (more less) on my aftermarket meter and the stock goes all the way to the top,, after that is total downhill cause the check engine light comes on (for a second or so) and i start to worry cause i dont want another bhg,, i think im experiencing fuel cut?.. what could be the reason for that boost pressure? i dont have any mods, only hks mushroom filter and hks ssqv bov and my exhaust has no catz just a muffler with a 4 inch tip. I want stock boost not this crazy thing,, could it be that my boost pressure sensor has gone bad? or my wastegate actuator? or the timing is off??... when idling it doesnt shake or knock nothing like that, the idle is perfect it sounds clean and deep... ANY ADVICE?

cre · 03-31-2010, 07:59 PM

you should be hitting fuel cut earlier, IMO. You are overboosting, unlikely that two different gauges are both wrong and the ECU doesn't monitor boost pressure. check the error codes yet? I bet theres one for abnormal boost pressure.

Check the waste gate, actuator and vacuum hoses.

Bill UK · 03-31-2010, 08:25 PM

Without a doubt, no cats and shimmed waste-gate will produce 15 psi resulting in fuel cut-out.

pacman7mgte · 03-31-2010, 09:05 PM

Quote:

Originally Posted by Bill UK

Without a doubt, no cats and shimmed waste-gate will produce 15 psi resulting in fuel cut-out.

Who said anything about shimmed wastegate?

Bill UK · 03-31-2010, 09:59 PM

No one, but thought I'll mention it as mine did the same when I first bought my first Turbo Supra, just in case yours is shimmed. I ended up fitting the second cat back on.

03-31-2010, 05:02 AM	#1
pacman7mgte Stock Join Date: Mar 2010 Location: Texas Posts: 23	overboosting i have a 91 turbo supra (automatic transmission ),i need some advice.. my car is drivable, but when i hit the gas to pass someone or just because, the boost needle goes up to 15 psi (more less) on my aftermarket meter and the stock goes all the way to the top,, after that is total downhill cause the check engine light comes on (for a second or so) and i start to worry cause i dont want another bhg,, i think im experiencing fuel cut?.. what could be the reason for that boost pressure? i dont have any mods, only hks mushroom filter and hks ssqv bov and my exhaust has no catz just a muffler with a 4 inch tip. I want stock boost not this crazy thing,, could it be that my boost pressure sensor has gone bad? or my wastegate actuator? or the timing is off??... when idling it doesnt shake or knock nothing like that, the idle is perfect it sounds clean and deep... ANY ADVICE?

03-31-2010, 07:59 PM	#2
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	you should be hitting fuel cut earlier, IMO. You are overboosting, unlikely that two different gauges are both wrong and the ECU doesn't monitor boost pressure. check the error codes yet? I bet theres one for abnormal boost pressure. Check the waste gate, actuator and vacuum hoses. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

03-31-2010, 08:25 PM	#3
Bill UK AEM EMS Join Date: Jul 2006 Location: UK Posts: 891	Without a doubt, no cats and shimmed waste-gate will produce 15 psi resulting in fuel cut-out.

03-31-2010, 09:59 PM	#5
Bill UK AEM EMS Join Date: Jul 2006 Location: UK Posts: 891	No one, but thought I'll mention it as mine did the same when I first bought my first Turbo Supra, just in case yours is shimmed. I ended up fitting the second cat back on.