proud 1st time owner of 87 supra turbo

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

cre · 03-30-2012, 03:34 AM

There may be vacuum line problems but the code 41 and code 51 are going screw with throttle state transitions (ie: the ECU cant's tell that you're flooring it until it's been floored for a few seconds already and it has a difficult time knowing when it's supposed to start modulating the ISCV for proper idle). The code 24 is going to screw with your fuel mixtures. While code 51 could just be an alignment issue the code 41 indicates damage in the TPS or its wiring.

I don't entirely understand your question about the head gasket. Yes, there is a ledge which protrudes out from under the head on the driver's side. It's supposed to be there. What else are you asking?

marcusproctor90 · 03-30-2012, 05:44 AM

Well I know my alignment is off and I believe the 24 code came up because I disconnected the o2 sensor for a minute. I hooked it back up but it still read.but I guess my main question is why would my car die after I floor it then let off the gas?

cre · 03-30-2012, 07:25 AM

Code 24 has nothing to do with the O2 sensor.... N O T H I N G.

As I've mentioned, all of these codes are in one way or another capable of affecting your throttle and idle transitions. Please don't make me bang my head on my desk.... I do that far too often around here. You've proven you can check for codes. Now go that extra three feet and fix them. There are many things which cause the stalling... I suggest we speculate on the other possibilities AFTER you fix what your ECU is already telling you is suspect.

marcusproctor90 · 04-09-2012, 03:59 PM

Welll I think I solved the stalling issue. There is a little adjustmentbolt/screw where the actual throttle rod meets the rest of the throttle body. I adjusted that and the stalling stopped. I figured it was snapping the throttle all the way shut before. I still have code 24 tho. So if its not the o2 sensor what is it? I only thought that cuz I read it on another forum.

03-29-2012, 06:00 PM	#2
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

03-30-2012, 03:34 AM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	There may be vacuum line problems but the code 41 and code 51 are going screw with throttle state transitions (ie: the ECU cant's tell that you're flooring it until it's been floored for a few seconds already and it has a difficult time knowing when it's supposed to start modulating the ISCV for proper idle). The code 24 is going to screw with your fuel mixtures. While code 51 could just be an alignment issue the code 41 indicates damage in the TPS or its wiring. I don't entirely understand your question about the head gasket. Yes, there is a ledge which protrudes out from under the head on the driver's side. It's supposed to be there. What else are you asking? __________________ 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 --->

03-30-2012, 07:25 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Code 24 has nothing to do with the O2 sensor.... N O T H I N G. As I've mentioned, all of these codes are in one way or another capable of affecting your throttle and idle transitions. Please don't make me bang my head on my desk.... I do that far too often around here. You've proven you can check for codes. Now go that extra three feet and fix them. There are many things which cause the stalling... I suggest we speculate on the other possibilities AFTER you fix what your ECU is already telling you is suspect. __________________ 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 --->

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03-29-2012, 02:38 PM	#1
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	#3
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

03-30-2012, 05:44 AM	#5
marcusproctor90 Stock Join Date: Mar 2012 Location: coos bay oregon Posts: 10	Well I know my alignment is off and I believe the 24 code came up because I disconnected the o2 sensor for a minute. I hooked it back up but it still read.but I guess my main question is why would my car die after I floor it then let off the gas?

04-09-2012, 03:59 PM	#7
marcusproctor90 Stock Join Date: Mar 2012 Location: coos bay oregon Posts: 10	Welll I think I solved the stalling issue. There is a little adjustmentbolt/screw where the actual throttle rod meets the rest of the throttle body. I adjusted that and the stalling stopped. I figured it was snapping the throttle all the way shut before. I still have code 24 tho. So if its not the o2 sensor what is it? I only thought that cuz I read it on another forum.