Getting fuel cut, help please!

[Abe'sGST]

Ok, so I got my gst 2 months ago and it came with a few mods. Every time I give it some gas at about 4500 rpm's i get fuel cut, and it smells straight up like gas, so i'm sure its running rich. It has an apexi SAFC and in settings its set on 0 on both low and high throttle. I want to fix this and what i would like is to remove the SAFC but i talked to the previous owner and he said it wouldn't run right if i did that. Is that true? If it is what would be the best settings for it? help please!

 

[bryanwheat]

That mbc is a 1 way valve so there will be no vacuum present. But when you go into boost it will open up and leak pressure assuming that it is set at a low psi. Yes take it out and put a hose directly to the bov as i stated before. ALSO, check on your wastegate to see how it is hooked up being that there is no line going to the mbc right now. The hose for the wastgate could be just sitting there un hooked which will cause the turbo to run max boost.

 

[Abe'sGST]

so i can do it both ways: hooking up the hose from the mbc nipple to the wastegate nipple, and taking off the mbc and just run a hose straight to the bov? which way is safer for the engine?

 

[bryanwheat]

I didn't suggest 2 ways to do anything. I suggested to remove the mbc from the bov line completely and run a new fresh piece of hose from the intake manifold to the bov. The mbc shouldn't be ran off the bov hose. It needs to be in between the nipple on the turbo compressor housing and the wastegate actuator.

 

[Abe'sGST]

ooo ok, i see...so just take it off and hook it up between the wastegate nipple and the turbo compressor housing... sorry man i was getting confused

 

[bryanwheat]

Yeah if you want it hooked up than do that. I would just leave the factory boost controller hooked up if i were you until you get everything else worked out, or just run with the hose directly from the nipple on the turbo to the wastegate with no boost controler.

 

[Abe'sGST]

also how do i know how much boost its set to?

 

[Calan]

OP - It sounds like you are just running rich and need a tune. Get your boost controller hooked back up, do a good boost leak test, and work on your tune.

 

[Abe'sGST]

ok, what does the stock boost controller look like and where is it at?

 

[bryanwheat]

Really?

And what happens when the leak is at an injector or somewhere else after the wastegate source? What about all the people that run the wastegate source straight off the compressor housing? Does the turbo just keep spinning madly and over-running the MAF because it knows that air is leaking somewhere downstream past the wastegate source?

*********

OP - Boost leaks don't cause fuel cut; they cause the car to run rich, exactly like you are describing. Too much air entering the engine (for any of a number of different reasons) causes fuel cut, and it feels like you hit something HARD when it happens. IF the leak was big enough and IF the turbo was being allowed to over-boost, then it's possible...but at that point you would most likely be running pig rich and the ECU would be in limp mode. And if you are running at WOT with an IC pipe off or something to cause those conditions, well...

Get your boost controller hooked back up, do a good boost leak test, and work on your tune.

It all depends on how big the leak is. If you have a giant leak in the intake manifold and the wastegate pressure source is on the turbo than you will still see less pressure at the pressure source at the same airflow. You have to achieve your target (pressure that the controller is set to) before the wastegate opens. The bigger the leak, the faster the turbo will have to spin to keep the pressure high enough to open the wastegate. The faster the turbo spins, the more air is being pulled thru the maf.

Are you assuming that it is impossible to hit fuel cut on the stock turbo? Instead of saying why fuel cut can't be achieved by a boost leak, why don't you explain it. There are plenty of people that understand and know why it does cause fuel cut

http://www.dsmtuners.com/forums/new...5h-cause-fuel-cut-otherwise-stock-engine.html

ok, what does the stock boost controller look like and where is it at?

The stock boost controller is a black solenoid below the intake pipe mounted on the frame rail. There will be a t in the hose between the source and wastegate actuator. From that t there will be a hose that runs to one side of the solenoid, and the other side of the solenoid goes into the intake pipe thru the little nipple on the front of it.

 

[Calan]

Are you assuming that it is impossible to hit fuel cut on the stock turbo?

No. I'm simply asking you not to tell the OP:

That mbc being open like that will cause the car to fuel cut because it is causing a big boost leak

Because the OP is describing an overly rich condition (and not fuel cut) in the first place.

 

[Abe'sGST]

thank you man, tomorrow when i wake up in the morning thats what im gonna look for, hopefully that solves my problem. once again thanks man

 

[bryanwheat]

I have done nothing of the sorts. I will tell the original poster the truth of the matter. I don't need you to tell me that i am wrong, and that i can't tell him something that is correct. You obviously don't understand. Don't be a dick to me because you can't fathom how this works. Sorry for being right and help full about something. By the way, i DID not directly tell this guy that he has fuel cut. You are putting words in my mouth once again.

 

[Calan]

After reading Wes's comments in the thread that was linked to above, I'll retract my implication that boost leaks don't lead to fuel cut, as they obviously can in some situations (although they don't cause it; and every boost leak I've personally seen has led to other problems rather than fuel cut). And I'll stand by my opinion that the OP is most likely experiencing a tuning issue or boost leak that is causing him to run rich.

Otherwise... my bad for posting generalized information, and apologies for the argument.

I've also cleaned up my posts to avoid any confusion in the future.

 

[knochgoon24]

OP, you need to figure out if the injectors are stock. Look at the part number on them.

If they have a blue top, look for the part number INP-009. It should say B450L on the other side. If they have a black top, look for the part number INP-018 and it should say MDL450 on the other side. If either of those are true, then you have stock 450cc injectors. If they are not stock, you'll need to use the SAFC to get the car to run right.

What other mods, that you know of, have been done to the car?

 

[Abe'sGST]

just the ones i listed before...safc, turbo timer, aftermarket bov (not sure which), dats all i know of...but what imma do is try to hook up my boost controller and see how that turns out

 

[knochgoon24]

Because adding more boost will fix the problem.

-Do a boost leak test and fix any leaks.
-ID your injectors so you can set the SAFC correctly.
-Loop the hose from your pressure source to your wastegate directly. This makes it so you run the minimum amount of boost that you can.
-Get everything else on working correctly.
-Then maybe it would be an acceptable time to install the boost controller.


EDIT: It looks like there's a j-pipe in the background of your one photo. The stock turbo wouldn't have that. So somewhere along the line, someone put a different turbo on. Now you need to ID the turbo too. Look on the compressor cover.

You must be logged in to view this image or video.

You need to get the number off the flat area show in the upper left hand side. It will be probably be one of these:

14B
49178-01010
49178-01030
49178-01400
49178-01410

Small 16G
49178-01520
49178-05200

Big 16G
49178-01420

Evo I Big 16G
49178-01450

Evo II Big 16G
49178-01460

Evo III Big 16G
49178-01470

 

[Abe'sGST]

ok, thats what im going to do, thanks man...also do you by any chance know what bov is in mines?

 

[LiquidX]

It looksto be a TurboXS piece but I'm not 100% positive. You NEED to have your BOV recirculated back into the intake which would mean getting a different BOV (stock 1g works with adapter works well).

If you have stock injectors and are on a at the minimum of a 14b you do not want to have your boost pressure above 13psi unless you have larger injectors so you are not at or near 100% IDC. You will have a hair more play with a 14b but the larger your go, the more CFM is blown at the same "psi" and that is what you need to account for.

 

[Abe'sGST]

ok so i took of my mbc and just ran the bov straight to my intake and the car drives a whole lot better, instead of getting fuel cut at about 3500-4k rpms i get it at about 6500 rpms which my guess is that it has to do with the safc now, but now i dont smell the unburned gas like i used to. Now its just to figure out if my injectors are stock ### if they are, bye bye afc

also what do you mean by having to get my bov recirulated? it seems like its working fine

 

[bryanwheat]

ok so i took of my mbc and just ran the bov straight to my intake and the car drives a whole lot better, instead of getting fuel cut at about 3500-4k rpms i get it at about 6500 rpms which my guess is that it has to do with the safc now, but now i dont smell the unburned gas like i used to. Now its just to figure out if my injectors are stock ### if they are, bye bye afc

also what do you mean by having to get my bov recirulated? it seems like its working fine

It means running the blow off valve outlet back into the intake pipe. You bov does not allow for that, so it would be a good idea to pick up one that does such as a 1g bov with 2g mount.

 

[Abe'sGST]

do i have to do that tho? what is it going to make a difference on? my sorry man im lost

 

[bryanwheat]

You could use the search button these questions because this has been answered thousands of times, but i'll help you out. The Blow off valve releases air pressure when the throttle plate is closed to prevent the turbo from rapidly slowing down. This air that is releases has been measured by the maf sensor and is calculated into the air that should be in the intercooler piping going into the engine. When it doesn't go into the engine or back into the intake pipe (after the maf sensor) the car will run rich because of less air than what it thinks it has. This can make the car stall out between shifts, and will also make the car a bit less responsive when you get back on the throttle because of the extra fuel in the cylinders. It can also cause problems with idle, and bucking at very light throttle cruising.

 

[Abe'sGST]

i mean i know what a bov does, im just asking why do i have to change mines for? it seems like its working fine to me, its some aftermarket one, idk which tho

 

[jed344]

Im sure your bov is working fine. The problem isnt with the bov it is with the car not knowing you have it vented. You "should" recirculate it back into your intake.

 

[Abe'sGST]

do u think thats what is causing mu fuel cut? whats the best thread in here that will help me recirculate it?