pow

soulreaver

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Apr 4, 2005
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i got an 89 supra turbo, when i'm driveing it makes a pop when i shift. if i am getting on i a little it will backfire sometimes when i shift into the next gear. i looked at all the pipes and i doesent look like they are cracked so i dont think thats the problem. i have it timmed up farther than what its sapposed to be, when its at its stock time it will backfire alot more than it does now plus its alot slower when its like that. the o2 censor is not old and the air filter is not bad. it has one of its cats removed but the one on the below the manifold is still there. anyone know what could cause this? oh and the wires and plugs are new. thanx
 

shaeff

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check your codes. my bet is that you have a code 52. (knock sensor/s) my car backfired like crazy when i had code 52.

-shaeff
 

shaeff

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go in the engine bay. right near the battery there's a little box that says 'diagnostic' on it. open it up, and jump terminals t1 and e1, (or te1 and e1, depending on year) turn all accessories off, and turn the key to 'on'. watch the engine light. it'll blink in a sequence, with 1 second breaks between numbers.

example: blink blink blink blink blink (one second space) blink blink = code 52, knock sensor troble code.

check this out:

http://www.cygnusx1.net/supra/techtip/engineerrorcodes.html

then get back to us, and we'll go from there. the first thing you should always do is check the codes. many times, this will tell you immediately what's wrong with your car.

-shaeff
 

SidewayzSupra

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Mar 30, 2005
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Ok this might be a stupid question but if your bov is vented to the atmosphere what causes the backfire. Running rich??? Thanks I have the same problem and I'm running a Greddy Type-S bov.
 

rakkasan

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SidewayzSupra said:
Ok this might be a stupid question but if your bov is vented to the atmosphere what causes the backfire. Running rich??? Thanks I have the same problem and I'm running a Greddy Type-S bov.

When you vent to the atmosphere, you're releasing metered air which the ecu is going to supply fuel for. Hence being rich.
 

shaeff

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rakkasan said:
When you vent to the atmosphere, you're releasing metered air which the ecu is going to supply fuel for. Hence being rich.

and yes, causing you to backfire.

-shaeff
 

SidewayzSupra

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So in theory with the stock bov I noticed when unhooked from the intake it leaks once boost rises. If I plugged the intake side and added my Greddy(atmosphere) the car will run a little richer all the time, right? So if I cranked up the boost a little it shouldn't do any damage? Just a thought. Running a little rich never hurts anything does it? Thanks
 

shaeff

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SidewayzSupra said:
So in theory with the stock bov I noticed when unhooked from the intake it leaks once boost rises. If I plugged the intake side and added my Greddy(atmosphere) the car will run a little richer all the time, right? So if I cranked up the boost a little it shouldn't do any damage? Just a thought. Running a little rich never hurts anything does it? Thanks

eh, no. an atmospherically vented BOV doesnt make you run rich all the time, only when you shift, or coast to neutral. pretty much the only time you run rich is when the BOV lets off excess pressure. if it was open all the time, thats called a boost leak, and sure, you'd run rich, but you still wouldnt go anywhere!

so, in short, no, that wont work, as the vented BOV only causes you to run rich when it is activated.

-shaeff
 

soulreaver

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Apr 4, 2005
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it is a code 21 but the car ran the same when i put a new o2 on it. and thats the only code it trows. where can i get an o2 at besides the dealer?
 

shaeff

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soulreaver said:
it is a code 21 but the car ran the same when i put a new o2 on it. and thats the only code it trows. where can i get an o2 at besides the dealer?

did you clear the codes after you replaced it? (if not, pull the EFI fuse in the engine bay fuse box for 30 seconds, then re-check them)

-shaeff
 

soulreaver

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Apr 4, 2005
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ok i put the timing back to stock and now it backfires more than it did. i pulled the fuse to reset the computer and now it doesnt throw a code.