proud 1st time owner of 87 supra turbo

[marcusproctor90]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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.