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? http://imageshack.com/a/img537/9310/XN6NLJ.jpg

[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?

[Rocketbunny240sx]

No the engine sounded the same it was running the same and not even the professionals knew till they popped off the valve cover

[Rocketbunny240sx]

They thought it was something minor like a vacuum leak

[Ilya]

hmmmm. that is some silent sniper Chris Kyle stuff right there!!

[Kingtal0n]

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.

BS. I bet they only told you that. A running Sr20det (that sounds normal, no clacking tapping noises) will never have issues with the valvetrain unless you install aftermarket cams/springs incorrectly and most of the time that ruins the entire engine (journal scores, dropped valves, etc...). Think about this, if the engine is boosting fine then the valves must be opening correctly, which means the camshafts and springs are doing their jobs.

Your bypass valve (blow-off) was causing the idle drop / rich stall condition you had. That is why tightening it seemed to help. You could have further diagnosed the issue by tape'ing the damn thing shut with some regular duct tape and go for a drive to verify. Shady mechanics that notice you know nothing about cars will tell you whatever you want to hear and charge your ignorance.

[Rocketbunny240sx]

Tbh i really dont know. I only just got the car for like a month. Like i said i have hks camshafts but apparently they said one of the valves or lifter is worn out and had a big gap or something like that which caused some mix up

[Kingtal0n]

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.



So lets talk about this as well. The factory intake rubber (and all similar length inlet tubes, like the greddy) is designed with the factory bypass valve in mind, meaning that, at idle, and during off-throttle conditions, the bypass is leaking air back to the rubber intake tube to prevent this exact problem.

When you install an aftermarket Bypass, such as a HKS SSQV, or any bypass that holds shut at idle, the air will flow backwards through the turbocharger (instead of through the bypass) at idle and the maf sensor will see that and the engine will run rich when you lift from the throttle. You can fix with an extended/bendy inlet tube, or running an open bypass at idle (such as a recirculated greddy type-S)

[Kingtal0n]

Tbh i really dont know. I only just got the car for like a month. Like i said i have hks camshafts but apparently they said one of the valves or lifter is worn out and had a big gap or something like that which caused some mix up

Its complete nonsense. You cant even see the valves or lifters without taking apart the engine. And if a valve was bent or ruined, A: the car wouldn't run well B: compression will be lower (a compression test is free and easy to do) C: if they took apart the engine and found a bent valve, they should return it to you for proof. Never take anyone's word. Also, a real shop performs a compression test before touching anything, or making any bold claim about a valve/lifter. Where are your compression test results?

[Rocketbunny240sx]

they did that tho they took the valve cover off and did a few checks around it and found it.

[Kingtal0n]

they did that tho they took the valve cover off and did a few checks around it and found it.

taking off the valvecover is not taking apart the engine. to see the valves you have to pull the head off the engine. Which means removing exhaust manifold, intake manifold, all plumbing, turbocharger, etc....

You can NOT just look under a valvecover and see a bent valve. You can't really see anything except whether the rockers are all intact and if the lobes look good.

Also... "Found It" that found WHAT? You still havnt been specific with what exactly "they found". Nobody, even you, has any clue what "they found" because they probably didnt find anything.
You are getting scammed, is my diagnosis, based on the information you have provided.

[Rocketbunny240sx]

Im probably gonna have to have a look at this myself. I'll take it apart and see whats going on.

[Croustibat]

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.

They lied, probably just add a sticker to your ECU. There are some nismo ECUs but they are different, old, and your map would not fit on it.

Also if the maps you have are set for 104 octane, you'd have melted your pistons or made holes in them. High octane = more timing = tons of detonation and swift engine death with regular octane.

Go away from that shop.

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.

They lied again, go away from that shop. Your car would not run at all if you had a "blown lifter or bent valve". You'd hear it . A blown lifter would sound like a hammer in the engine, plus it would surely have broken a rocker as it would only have 1 lifter to push on. Your engine would not be turning anymore. Same as the bent valve.

No the engine sounded the same it was running the same and not even the professionals knew till they popped off the valve cover

Let me guess ... they now want to sell you new cams and are happy to recycle your dead cams back ?

Can you name that shop, so other people DON'T end up there ?

[Rocketbunny240sx]

They lied, probably just add a sticker to your ECU. There are some nismo ECUs but they are different, old, and your map would not fit on it.

Also if the maps you have are set for 104 octane, you'd have melted your pistons or made holes in them. High octane = more timing = tons of detonation and swift engine death with regular octane.

Go away from that shop.



They lied again, go away from that shop. Your car would not run at all if you had a "blown lifter or bent valve". You'd hear it . A blown lifter would sound like a hammer in the engine, plus it would surely have broken a rocker as it would only have 1 lifter to push on. Your engine would not be turning anymore. Same as the bent valve.



Let me guess ... they now want to sell you new cams and are happy to recycle your dead cams back ?

Can you name that shop, so other people DON'T end up there ?

Well actually they were right. I opened up my ecu and they had a brand new board in. They also added a usb port so i can manually tune it which was pretty cool. And my cam shaft when i had a look at it one of the bearings or thats what i think its called is rounded out from hitting the one lifter many times and its a circle now. If i ran that car any more probs would have blown up. So they set it at low boost and ordered me some new cams and lifters for a grand which is pretty cheap actually. Then they will bring my car in for a tune for 300 or so.

[Croustibat]

Well actually they were right. I opened up my ecu and they had a brand new board in. They also added a usb port so i can manually tune it which was pretty cool. And my cam shaft when i had a look at it one of the bearings or thats what i think its called is rounded out from hitting the one lifter many times and its a circle now. If i ran that car any more probs would have blown up. So they set it at low boost and ordered me some new cams and lifters for a grand which is pretty cheap actually. Then they will bring my car in for a tune for 300 or so.

Dude, words have meanings, if you don't bother using them properly we have no way of knowing what you mean. So first you have a nismo ECU, then you have a new nismo board in your ECU with an USB port ...

Meaning you have either a nisTUNE, or a nismoTRONIC, but neither are a nismo ECU ...

Do as you want, just dont come crying. mapped at 104 octane, worn AAC so "they set it at low boost"... you are either a genius troll or a genuine idiot. I really can't tell.

[Rocketbunny240sx]

Dude, words have meanings, if you don't bother using them properly we have no way of knowing what you mean. So first you have a nismo ECU, then you have a new nismo board in your ECU with an USB port ...

Meaning you have either a nisTUNE, or a nismoTRONIC, but neither are a nismo ECU ...

Do as you want, just dont come crying. mapped at 104 octane, worn AAC so "they set it at low boost"... you are either a genius troll or a genuine idiot. I really can't tell.

Its not like i always 104 octane it. Im saying it can 104 octane and i usually only do that on a track then have it serviced and checked. I may not know everything but i know enough to be able to fix it now