Brake light switch and neutral safety switch problems

[btwilson86]

Originally Posted by cre

details on how to check diagnostic codes is posted in the FAQ

Originally Posted by jtown125

I don't have a reader I said that

Alright, a little bit of clarification:

I believe cre meant to type "BOV" and not "BOS", referring to an aftermarket Blow Off Valve.

Checking codes on MKIII Supras does not require the use of a code reader, just a jumper wire or a paperclip. As stated above, details on how to check codes are here in the FAQ. Once again, keep in mind that just because the CEL is not on it doesn't mean that there are no error codes stored.


When you do the 4-N and 5-N shift, will it still die if you accelerate at partial throttle without boosting? Does it do it under half load? Full load?
Also, does it cut out regardless of what engine RPM's you shift at (lo vs hi)?

[btwilson86]

Oh, one other thing....

You're saying it's shutting off. Is just the engine shutting off, or does all electronics shut off?

[jtown125]

give me a second....

[jtown125]

Alright...

It does have a BOV. And it wasn't doing was it was supposed to do...how would it cause the car to shut off immediately?

I don't think that the rpm's have anything to do with the car shutting off. I could be wrong.

I took it out again after the last post and it died stopping from 3rd-N too....

but it has yet to shut down from 1-N or 2nd-N. And im always shifting anywhere from 2500 to 3500 rpm's.

Of course when since the gears are high in it i usually just leave it in 4th when going 40 mph. running 2500 or a little higher and then putting it neutral.

With the engine only having 3,000 miles on the rebuilt motor all of these things that people are saying aren't making any sense to me. They are the original parts though, so wear is def possible.

It hasn't died from full boost and quick let off of gas... BOV still does what it is supposed to do...from what I can hear.

I don't know if back pressure has anything to do with it...but the down pipe has 2 pipes and one is cut off. Which would cause a lot of backpressure.

It "dies", it just does it without any hesitation. my def of dying is chug chug chug chug....die....

All the warning lights will come on and i just put it back in gear and remove the clutch...

[jtown125]

And i don't know about the electronic things...i would assume they stay on...the cd player don't work half the time so it usually stays off.

[btwilson86]

Originally Posted by jtown125

And i don't know about the electronic things...i would assume they stay on...the cd player don't work half the time so it usually stays off.

I suspect that since the warning lights come on, it's just your engine cutting out and not the entire car. This also makes me think it's not as likely to be a bad ground or a short

[btwilson86]

Okay, I'm starting to suspect the BOV.

Stock turbo supras came with a bypass valve instead of a blow off valve. Biggest difference between the two is that the bypass valve will redirect excess boost pressure back into the intake pipe between the AFM and the turbo, meaning all of the air stays in the intake system and is accounted for by the AFM. Blow off valves vent the excess pressure to atmosphere. Our computers are programmed to "expect" that air to stay in the intake system, so if it is vented to atmosphere the engine will briefly run rich after shifting (which can cause it to chug and die) because it anticipates more air in the intake than what is actually there.

Basically, as far as the computer is concerned, each time you shift your BOV creates a giant boost leak. The only reason I can think it does it in the higher gears is because it takes longer for the RPMs to get there, allowing you to build more boost pressure thus loose more air/pressure when you shift.

[jtown125]

One thing i do know...IT DOES RUN RICH!!! lol

So, lets go ahead and say its the blow off valve. Y would it not die after boosting in a single gear?

And to fix it?

[btwilson86]

Well, the only thing I can think of is that the ecu has time to realize what happened and fix the fuel curve as the engine revvs down.

I was reading an earlier post of yours and you said that it doesn't die off after full boost, so I'm assuming during these times you reach a higher rpm which could help support my above statement.

Fixing the problem, AFAIK, would require either tuning in some way (piggyback ecu or something along those lines) or replacing the aftermarket BOV with a factory or an aftermarket bypass valve (they do make them). You usually don't get the same sound, but they provide better performance over an OEM one. If your donor car is a turbo and has the required parts, swap them in and go for a drive. If it still happens then that's not the problem, but I really think that will fix your problem.

FYI, when I had my 7MGTE I put an aftermarket high-flow cone filter and a AFM adapter on mine and it made the turbo spool and OEM BPV much more audible

[jtown125]

I don't know how it can do it so fast though?? It is almost instintaniously.

Is there a way to reset the computer and maybe it will fix it in itself?

Since the BOV has been on for a while...y now?

I drove it home 600 miles from mississippi and not one problem.

And what was the cone shaped thing you were talking about?
how does that set up work?

BTW: The BOV is welded on to the intake.