240sx 1990 hatch stalls (when stopping)

[Rocketbunny240sx]

Hi guys i have a fully built 240sx and i have it tuned at 19 psi but i recently had a vaccum leak and had the hoses replaced. Now what happens is my car when coming to a complete stop it will stall. (Only when i accelerate fast and then slowdown or push the clutch in it will idle extremely low or stall) atm i am running 14 psi low boost because of this issue. Does anyone have any ideas? Also the car tends to be len or have too much air some times.

[Fuego]

You still have a leak.

[EnnEssEnnKAT]

My car does this but it's stock ka. Friends think it's the IACV or whatever the thing is back there on the intake manifold. There's a FSM procedure in EF + EC to test it..mine failed. Good luck.

[Rocketbunny240sx]

Yeah idk my mechanic saids i need a new ecu? or something. He just recently replaced all the vaccum lines and my gauge saids its at -20 vaccum which is where its suppose to be

[badbob2121]

Running an atmospheric BOV setup?

[TheRealSy90]

You bov is not recirculated to the turbo intake, and is vented to the atmosphere. This causes a stalling effect when going down to idle from higher rpm's. Either recirculate the bov to the intake after the MAFS, or have the ecu re tuned to compensate for the vented bov.

[Rocketbunny240sx]

Yeah im running an atmo bov i have a greddy bov rz type and my mechanics did mention something about the bov or changing it.

[Fuego]

VTA alone does not cause this. The RZ is good if it's a real one, tighten that bitch up and report back.

[TheRealSy90]

Yes, another method that works is to tighten up the bov so that it only opens around the full boost pressure, and not at partial throttle or low boost. That little bit of surge you might hear won't hurt anything.

[Rocketbunny240sx]

So ive tightened it up to the max, any more and the nut might not be able to go on, it makes a nice sound xD but yet it still tends to want to stall. As soon as i come to a complete stop if i push the clutch in or put it in neutral the rpm drop to 500 sometimes lower. And then it will wanna try and come back up. Sometimes it succeeds some times it stalls :/. Another thing about the car is it does tend to become too len and some times too much air. The build of the car made it like so its all custom piping i guess. I just recently got the car so im not so familiar with it. I had the intake gasket leaking a while ago and replaced it and i had a vaccum leak somewhere but i manage to find it and replace it as well. I have 700cc injectors on it i think and a gt37 turbo i believe? Maybe its the mixture? Or the injectors? Idk but im up to try just anything to get her fixed

[Rocketbunny240sx]

Heres a picture if her maybe you guys and find something wrong?

[Highway Riding]

What is idle set to? Raise if @ stock RPM I'm thinking

[Rocketbunny240sx]

The timing was reseted to its optimum so its doing perfectly fine when its idling. It idles at 1000-1500 sometimes when cold it warms from 1500-2000 then back down to 1000

[Rocketbunny240sx]

Also i tried to tighten the bov some more it seem like it works. I tried to boost it then slow down quick it started to wanna stall then i gave it some gas and it popped back up.

[badbob2121]

If you run an atmospheric BOV you need to have an AFC so you can adjust the Decelleration air table so that the car doesn't stall when the BOV opens and releases the air into the atmosphere rather than back into the intake track

[Croustibat]

ALL BOVs leak at idle. Some leak less than others, but your choice is either a retune with a higher fuel recovery threshold, or recirc your BOV.

Or both. I went for both. Works great.

Edit: did you get a new tune when changing injectors or setting your boost higher ? Because if you dont, you should start there before blowing your engine.

[EnnEssEnnKAT]

Does a recirculated BOV significantly reduce that awesome noise, or can you still hear it plenty?

[Croustibat]

If you noise, use a loud speaker.

[s13Cory]

My 240 does the same thing with stock ka and I've been getting told its the IACV but I haven't gotten around to installing a new one yet to see if it fixes it.

[Rocketbunny240sx]

Well i can tell you it didnt reduce the noise the car is more responsive and the idle isnt as bad. Im running low boost atm running at 14 psi. High boost is 19 psi. The car seems to be able to handle it perfectly fine no jerks or anything it still boosts very powerfully but its just when decelerating that it tends to stall. Tightening the bov helped it abit. Its better then it was. Less stall but still it does want to stall a few times.

[S-Verteen]

Just a quick guess here but have you checked your tps sensor?

[ultimateirving]

Ok so since your idle is high and your still stalling with a tight bov you need to take off the iacv and thoroughly clean the little valve and test to make sure it's properly installed/wired and fully functional. I have run a greddy type s for years atmospheric and I don't stall between shifts or on decel.

[Rocketbunny240sx]

Yes ive checked my tps sensor long before. That was the first thing i did. I had it cleaned and made sure it was running fine. And i have already done that i took it off and cleaned it off , wasnt sparky clean but clean. No change in it.

[cbh148]

Everybody always says IACV and MAF stuff in these kinds of threads, but you never ever see anybody report back that replacing those things or changing them made any difference.

I had this same problem, and what fixed it for me was having my SR's intake pipe extended to 18" (between the MAF and the turbo) with two 90 degree bends added.

[Rocketbunny240sx]

Ive already had the maf and the iacv cleaned and i even had it checked its fine their both fine. I had a leak coming from the pipe to the intAke. It blew a hole underneath and got loosened so i had to replace that. But now it needs a tune cuz it went out of place and everything isnt stabled

[cbh148]

Try resetting the ECU to clear the self-learn values in case they were "adjusted" for the leaky intake you previously had (even though that "adjustment" wasn't enough to prevent it from stalling). I'd invest in a cheap Consult USB cable ($25 shipped) so you can watch your sensor values in real time to see what's going on. But the stalling-when-letting-off-the-throttle issue that these engines love to have seems to be mostly due to intake pipes being too short and/or not having enough bends. The pipes will develop a vortex inside, upstream from the turbo, which will cross the MAF in that swirl motion and cause the element wires to read more air coming in than is really entering the intake. Also, surging when getting off throttle will cause the air in the intake to rapidly go forwards and backwards (even light surging that you can't really hear), which the MAF can't differentiate which direction the air is flowing, and so it meters it all as more air coming in, which causes it to dump fuel to accompany all that false air, which causes it to get super rich at that moment and try to stall out.

[Rocketbunny240sx]

Well i brought my 240sx in to a professional shop and they said their gonna change my ecu considering its old now. So their giving me a nismo ecu system to tune the car and btw yes you are right my digital gauge has told me multiple times the car has too much air flow then too len and then when stopping rich and then its difficult to restart the car cuz its too rich. So id have to rev the engine while starting to get it back up and running. I hope they pros can get it working im getting the car fixed by friday. So their gonna have a new ecu and a good tune. The car can run 104 octane and also its been daily driven at 19-25 psi but i had to set it to 14 psi stock due to the leakage right? Im gonna try and have it reset again.

[Ilya]

Leaky injector

[Rocketbunny240sx]

Hey guys so i figured out what happened. It turns out one of my lifters or valves blew up cuz of my camshafts i have hks camshafts and i guess it probably hopped or something happened there but thats what was causing all the problems. I hope this helps you guys out for future use.

[Ilya]

you are telling me that your valve train is messed up and you didnt hear ANY changes in the sound of the engine or how the engine operated? and even if you did hear it, you failed to mention that when asking us to diagnose the issue?