proud 1st time owner of 87 supra turbo

marcusproctor90 · 03-29-2012, 04:50 AM

This is my first supra and I want to learn all I can about the car from regular maint to performance upgrades. But my first question I have is is there a way to determine if my head gasket has been changed recently? I changed thehead gasket on my 95 accord myself and I realized there is a small ledge coming off the block that the corner of the gasket sits on that was visible after the motor was put back together. It was very obvious the. Gasket was changed. And I'm just curious if there's A way to tell on these supras

marcusproctor90 · 03-29-2012, 05:07 AM

And also when I really get on it then let off the gas really quick my car dies. I read on another forum that it may be the blowoff valve. Could that be the case?

btwilson86 · 03-29-2012, 01:16 PM

I don't have an answer for your hg question, but running a blow off valve (vented to atmosphere, not recirculated) can cause your engine to stumble and/or die when shifting. This happens because all of that air passed through the AFM, so the ecu expects the air that was just dumped to still be in the intake. The ecu then provides the amount of fuel to the engine needed for the volume of air it thinks is still there, causing it to run excessively rich.

You can eliminate this problem by running a bypass valve instead of a blow off valve (easy) or by running a system like MATT-PRO 2 (?) in speed-density mode (not exactly sure if that's correct; in any case this would be a better setup because you can eliminate the AFM, but my understanding is that it's incredibly difficult to set up). A search on the forum or Google should bring up several results for this particular problem, as it's very common

marcusproctor90 · 03-29-2012, 02:38 PM

This may be a dumb question but what is the difference between a blow off valve and a bypass valve? My car is completly stock except the catback exhaust I might add. So if either one of those is aftermarket my car does not have one. I just assumed that since my car was turboed it had a blowoff valve. Just not one that made sound when it releases pressure

btwilson86 · 03-29-2012, 06:00 PM

Typically, a bypass valve vents excess boost back into the intake after the AFM, whereas a blow off valve vents the excess boost out of the intake into the atmosphere. If your car is bone stock, it should have a bypass valve and shouldn't be suffering from the issues people with blow off valves have. I'd start diagnosing by checking for engine trouble codes and inspecting your intake and vacuum lines for leaks.

marcusproctor90 · 03-30-2012, 02:46 AM

I checked my trouble codes and I believe. 24 41 51 came up. Ill start checking my vacuum lines. It doesn't do it when I rev the motor only driving when the turbo kicks in

03-29-2012, 04:50 AM	#1
marcusproctor90 Stock Join Date: Mar 2012 Location: coos bay oregon Posts: 10	proud 1st time owner of 87 supra turbo This is my first supra and I want to learn all I can about the car from regular maint to performance upgrades. But my first question I have is is there a way to determine if my head gasket has been changed recently? I changed thehead gasket on my 95 accord myself and I realized there is a small ledge coming off the block that the corner of the gasket sits on that was visible after the motor was put back together. It was very obvious the. Gasket was changed. And I'm just curious if there's A way to tell on these supras

03-29-2012, 01:16 PM	#3
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	I don't have an answer for your hg question, but running a blow off valve (vented to atmosphere, not recirculated) can cause your engine to stumble and/or die when shifting. This happens because all of that air passed through the AFM, so the ecu expects the air that was just dumped to still be in the intake. The ecu then provides the amount of fuel to the engine needed for the volume of air it thinks is still there, causing it to run excessively rich. You can eliminate this problem by running a bypass valve instead of a blow off valve (easy) or by running a system like MATT-PRO 2 (?) in speed-density mode (not exactly sure if that's correct; in any case this would be a better setup because you can eliminate the AFM, but my understanding is that it's incredibly difficult to set up). A search on the forum or Google should bring up several results for this particular problem, as it's very common __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

03-29-2012, 06:00 PM	#5
btwilson86 Super Moderator Join Date: May 2007 Location: Billings, Montana Posts: 1,034	Typically, a bypass valve vents excess boost back into the intake after the AFM, whereas a blow off valve vents the excess boost out of the intake into the atmosphere. If your car is bone stock, it should have a bypass valve and shouldn't be suffering from the issues people with blow off valves have. I'd start diagnosing by checking for engine trouble codes and inspecting your intake and vacuum lines for leaks. __________________ 1989 7MGTE R154 Targa Top White Package w/Blue Interior Driftmotion 57trim CT26, Upgraded Intercooler, 2.25" Hard Pipes, 3" Turbo Back Exhaust with Test Pipe, HKS VPC w/GM 3 bar MAP sensor, APEXi S-AFC, Walbro 255lph fuel pump, ProSport EVO Series Boost / Fuel Pressure / AFR gauges, Lotek a Pillar Gauge Pod, HKS Type 0 Turbo Timer, Eibach Lowering Springs, Tokico Illumina II TEMS struts, custom powder coated Motegi Racing TrakLite wheels

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Installation of T61 turbo on a mkiii supra	ahruizguerra	MKIII Supra	1	12-02-2010 11:19 PM
Possibly Buying Supra 1994 Twin Turbo	bswan9015	MKIV Supra	6	11-05-2009 12:29 AM
First time Supra buyer. Tips/Advice. See setup inside plz	pisto	MKIII Supra	1	09-13-2009 01:28 PM
Turbo trouble with JDM supra	wollis	MKIV Supra	2	06-06-2009 08:41 PM
New to forum...1989 Bright Red Targa Turbo Supra Virgin, Pics included.	whowouldfigga	Show n Tell	3	03-13-2008 07:47 PM

03-29-2012, 05:07 AM	#2
marcusproctor90 Stock Join Date: Mar 2012 Location: coos bay oregon Posts: 10	And also when I really get on it then let off the gas really quick my car dies. I read on another forum that it may be the blowoff valve. Could that be the case?

03-29-2012, 02:38 PM	#4
marcusproctor90 Stock Join Date: Mar 2012 Location: coos bay oregon Posts: 10	This may be a dumb question but what is the difference between a blow off valve and a bypass valve? My car is completly stock except the catback exhaust I might add. So if either one of those is aftermarket my car does not have one. I just assumed that since my car was turboed it had a blowoff valve. Just not one that made sound when it releases pressure

03-30-2012, 02:46 AM	#6
marcusproctor90 Stock Join Date: Mar 2012 Location: coos bay oregon Posts: 10	I checked my trouble codes and I believe. 24 41 51 came up. Ill start checking my vacuum lines. It doesn't do it when I rev the motor only driving when the turbo kicks in