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Canadian monster
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596 Posts
Discussion Starter · #1 ·
OK guys, just got my car out of storage, i installed a turbo kit but i am still on the MAF. I also installed Exedy triple carbon clutch which is really light.

Here is my problem, when i drive, even slowly, and i am at say 20mph, if i push the clutch because a stop is coming and i want to let the car roll by itself, the rpm drops too quicly and the car shut off. If i leave the car in gear and push on the clutch at the last minute before i stop, everyting is fine. It also shuts off if i want to just move the car a couple of feet, like getting up the driveway, i have to rev the hell out of the car because the clutch is hard to drive and when i push the clutch, it shuts off.

i don't think it is my new BOV because i have not hooked up the vacuum yet.

Could it be because my flywheel is too light? what else could it be? I have not raised the idle yet.

thanks for any help
 

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1,136 Posts
My first impression would be the bov. is it an aftermarket one? either try tightening it or put the old one back in and see if its the problem.
 

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Canadian monster
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596 Posts
Discussion Starter · #3 ·
it's a Tial but it is not hooked up, i mean the vacuum. I did not even run it into boost yet.

i read somewhere that the Ecu had to relearn. Anyone can confirm this? I will also try to raise the idle.
 

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mine was doing that for a while, turns out it was one of the first signs of crank walk. Not sure if yours is but the best thing you can do is find out early and stop driving it. Otherwise it will wear down the thrust washers and into the block which isnt repairable. The only reason I bring up crank walk is you just installed a clutch and it wasnt doing it before. I had my clutch installed only a couple hundred miles when it destroyed my block.
 

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Canadian monster
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596 Posts
Discussion Starter · #6 ·
yeah but i didn't start the car with the clutch pressed in, i have like 15 miles on it and it was doing it exactly after i did all the mods.

And i tried a supra with crank walk and the car would shut of as soon as you pressed the clutch. Mine goes really well other than the problem i mentionned above. i am sure it is not crankwalk.

If it can help, i found this today. When i rev the car in neutral with the clutch press and i rev to let say 3000 rpm, the engine will go well and keep it's idle at 1200 (i adjusted it). If i rev to 4000 with the clutch press in, the car will make a quick stop at 1000 then die. if i slowly let the gas pedal of, it won't die, just when i give it a quick shot and let off.

i will try to make a video tomorrow and post it here.

thanks for your opinion though.
 

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Canadian monster
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596 Posts
Discussion Starter · #8 ·
i have not installed cams and to be honest i did not check if it did it when cold but it certainly does it when hot.

If i drive the car carefully and don't push on the clutch when my RPM is high, everything is fine. If i see that the car wants to die, i just give it a slight throttle bip and it goes back up in place. If i just let the car go to the stop without letting it go with the foot on the clutch pedal, it drives like a champ.

I am still on the MAF, could it be a problem? could it be because i don't have a BOV? (have not gone into boost yet) It really feels like the RPM is dropping too quickly and the ECU doesn't have time to react.
 

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Garage Queen Club
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2,822 Posts
At idle, rev the motor (w/o pressing in clutch). Does the RPM drop correctly and stay idling?

Press in clutch. Do rpms drop or rise? With clutchin, rev the motor, in neutral while stopped. Let the rpms settle with clutch still in.

Describe what happens
 

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Canadian monster
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596 Posts
Discussion Starter · #10 ·
ok, just went to try what you said, when i press the clutch the rpm doesn't move.

it will die if i rev it neutral with an agressive 4k+ rpm letting go gas quick, no matter if the clutch is pushed or not, no difference.

I really am starting to beleive that my problem is the BOV that i don't have routed back after the MAF. i read those thread which seem to have the same problem i have. Basically i have no BOV which is i suppose the same as having one vented to the atmosphere.

http://www.supraforums.com/forum/showthread.php?t=63108&highlight=dying
http://www.supraforums.com/forum/showthread.php?t=94089&highlight=dying

i checked on my wideband and when the car wants to die it is because my A/F ratio goes really low like in the low 10 and 9.
 

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Canadian monster
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596 Posts
Discussion Starter · #11 ·
i have a Tial BOV installed but not hooked up yet (vacuum), anyone has an idea how i could install a BOV without having to weld an other nipple or an other BOV on my intercooler piping? any kind of adaptor that would fit on the Tial flange to use like a stock BOV?
 

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Espresso Connoisseur
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1,636 Posts
I'd suspect the BOV is leaking. Try tightening the adjustment screw all the way or swapping back to the stock one all together. If it's open too much, even without a vacuum reference, it's venting your intake charge that was already calculated for.

Another thing to look into would be your idle air control system and TPS settings. If these are out of spec, they can cause fast-rev-drop stalling issues as well.
 

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Canadian monster
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596 Posts
Discussion Starter · #13 ·
well i just adjusted the tps so that's not it but what about the iacv? is there any adustment on this?

oh and the Tial BOV is not adjustable :(
 

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Espresso Connoisseur
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The Idle air control motor should be set by the ECU...that is assuming it's still in a range it can control. Also a fouled up IACV can cause idle issues if it's broken, malfunctioning or just plain needs cleaning out.

Regarding the Tial BOV...try connecting a vacuum source. I'm not familiar with that unit's internals, but it probably requires vacuum to keep it shut.
 

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Supra Owner Since 1996
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2,723 Posts
I have had similar issues after going single on MAF and LWF. My car runs pig rich and could be a major contributer. I'm going to try out the Map-Ecu in the coming weeks to account for the lost air dumped from the BOV. My ecu can't recorrect fast enough when the rpms drop to idle. It will stumble and die. So when driving I have gotten used to riding the throttle when coming to a stop. I can let off after I gradualy let the trottle down and the ECU stabilizes.
 

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Canadian monster
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596 Posts
Discussion Starter · #18 ·
Well i just rerouted a stock RX-7 BOV from the intercooler piping to the pipe before the turbo and i still get the same thing.

anyone else has an idea what it could be? Would going VPC get rid of my problem?
 

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Supra Owner Since 1996
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2,723 Posts
True. Tial to atmosphere.
 

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Garage Queen Club
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Verify your bov is opening and venting back to the front of the turbo (unhook it from the turbo inlet, have someone WOT at idle, and listen/feel for what is going on).

If you can verify that is happening, make sure the vented air is being dumped INTO the turbo, not 'backwards' towards the maf. You could be screwing the readings.

Also, there is a biss screw, small black allen screw under the throttle body which yo can try adjusting. This will open the plate a bit more at idle. Your idle plate may be dirty/gummy. Try spraying carb cleaner on it while idling or before turning ont he car.

I do not think this is crankwalk related. If you think you have crankwalk, you can easily go under the car and find a way to pry the crank pulley (carefully) while at the same time someon presses in the clutch. Then, pry it back against the engine. Do this when the car is off of course).

What you can also try, is put the car on a steep incline. Rev it at idle, see what happens.
 
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