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Discussion Starter · #1 ·
Hi all you supra owners, I need some help! I'm not a Supra owner and I don't know too much about supras, I'm posting this for a friend. He doesn't know anything about the car, he bought the car with A LOT of mods. what i can remember are

Trust T88 big single kit, SP downpipe, HKS Super Dragger Exhaust, HKS VPC, HKS GCC, HKS EVC IV, HKS 296 Cams, HKS Twinpower ignition, HKS adjustable cam gears, HKS Triple Plate Clutch, HKS fuel rail, HKS fuel injectors(not sure the size). and some other stuff....

boost is 1.5bar, car dynoed at 598rwhp and 580ish lbs/ft of torque. on the dyno sheet the curve shows a lot of spikes....

The car is not running right since he bought it, here are the problems

1. it idles very rough and low, I thought it might be the aggressive HKS 296 cams caused the rough idle, but it idles WAY too low at around 400-500rpm and it will stall when it's cold and no throttle is given. must hold the throttle to keep it from stalling.

is there a way to djust the idle? I tried to turn the Idle knob on the VPC but it doesnt seem to do anything.

2. the clutch is very rough, from what I've heard the HKS Triple disc clutch is supposed to be a very streetable clutch, but it acts like an ON/OFF clutch and it's not slippable. it's very hard to drive on the street. What problem it might be? or thats the way it is? most parts on this car was installed at SP Engineering.

after driving for a while, the exhaust temp shows about 500-600F, never went past 700F

lots of black smoke coming out of exhaust when boosting.

i think thats the most major problems on the car, all you supra owners please help my friend out. Thanks!

8 Posts
Well I dont have a supra but my friend does(BPU++). The rough idle could be from the bov in combination with the hks cams. That can make the idle pretty rough. The black smoke coming out of the exhaust is normal to my knowledge since the car has a downpipe and full exhaust. Some smoke is fine, but if there is a real lot of black smoke there could be a problem.


Discussion Starter · #3 ·
Do at least a compression test and if possible a leakdown test. Bad idle + lots of smoke could definitely be a blown motor. I hope that's not the case!


Discussion Starter · #4 ·
The motor was compression tested and changed a new head gasket(factory) recently. and the car pulls strong when boosting. so the motor shold be fine. when the car is warmed up, it won't stall just the idle jumps between 300-500rpm.

the bov is a greddy type-R and it's dumped into air. I'm guessing the black smoke is due to the car runs rich now. my turbo prelude did that when it hits boost...
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