1JZ-GTE Throttle Lift car starts bucking

[drzaeis]

Hey guys I've searched and can't quite find the answer. We have a 1987 Supra with a 1jzgte - 5 speed manual - race car only so no codes to read.

The problem is when you get on the throttle pretty heavily, as soon as you lift off the car will start bucking and occasionally back firing..it runs GREAT otherwise...

any ideas? blow off valve? the engine is a straight JDM stock motor. just runnung a cold air intake and a Denso 2jzgte fuel pump...

thanks in advance

 

[stevenr816]

Race car only= no code retrieval?


Really? Must I say more?



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[tlo86]

so its running rich...

 

[te72]

so its running rich...

That is what I gathered... although my 1j rarely backfires, no matter how hard I get on it. Certainly doesn't buck when getting off the throttle.

Perhaps his carrier bearing has gone bad?

 

[JPsToyota]

Race car only= no code retrieval?


Really? Must I say more?

Dude's got a point.


te may have an idea with some sort of drivetrain/slack issue if it's a "mechanical" bucking and not the engine. If the engine is surging, maybe you have a TPS issue? No idea why it would be only after full throttle though.

Do you have a list of things you've checked/tried?

 

[toy4speed]

what kind of fuel or engine management system? Not sure about the backfire, but bucking could be fuel cutting in and out when letting off the gas. With my standalone, some tuning of map pressure above 22" helped with my bucking, which was due to lean condition upon letting up of throttle.

 

[Poodles]

If you're on the stock ECU...you have codes to read.