Fuel Cut: What is it? How do I fix it? [merged]

[Slanted J]

All fuel cut threads are combined here.

I've tried doing a search but to no avail.

I was just wondering what Fuel Cut is. I've heard it tossed around alot, but do not actually know the details behind it. And, naturally, I can gather that its when the fuel is cut off, but when and why.


Thanx,
Jon

 

[crxp-o-s4now]

thanks man

 

[ddavisaf]

You didn't answer a single question. Is your car stock? Does it have fuel mods?

Now, answer my questions.
What kind of spark plugs and wires are in there?

 

[91dsmeclipse]

im getting fuel cut when i start boosting around 4,000 rpm i know for a fact i have a boost leak but i had a boost leak before this started happening do you think that the hole just got bigger. my boost leak is at the turbo i just want to know if this might be causing this before i go buy another turbo(their is no use to fixing the turbo the car has 189,000 miles on it with the orig turbo i think its time to be replaced) so what do you guys think

 

[DSM90AWD]

im getting fuel cut when i start boosting around 4,000 rpm i know for a fact i have a boost leak but i had a boost leak before this started happening do you think that the hole just got bigger. my boost leak is at the turbo i just want to know if this might be causing this before i go buy another turbo(their is no use to fixing the turbo the car has 189,000 miles on it with the orig turbo i think its time to be replaced) so what do you guys think

What do you mean a boost leak at the turbo? Is the compressor housing cracked?
Boost leaks are generally a result of loose IC, leaking BOV, disconnected VAC lines or even blown gaskets (BOV, Throttle Body). I've never heard of the turbo leaking boost unless the OEM boost nipple (which connects to the wastegate and BCS) is not capped

 

[91dsmeclipse]

when i did the boost leak you heard all the air comming out of the turbo i could,t pinpoint the spot but i checked everything else and no leaks

how do u test the bov?

 

[DSM90AWD]

Just to make sure I'm on the same page as you here.
When you performed a "Boost Leak Test" you had everything connected from the turbo outlet to the throttly body and "pressurized" from the turbo inlet.. right?

 

[Boost95]

Im still hitting fuel cut to this day. I got another TB and it doing the same thing. It wont hold any boost. When Im doing the boost leak test and I open the TB it still hisses out. Even with the "low mileage" TB i just got in the mail 2day.

 

[91dsmeclipse]

yes when i found out my turbo was leaking i disconnected the lower intercooler hose and pressure tested it that way to and it tested fine only thing that didt test find was the turbo. i read somewhere that the bolts to the manifold sometimes back off im going to take off the heat shield when i get a chance and see whats up

 

[crxp-o-s4now]

You didn't answer a single question. Is your car stock? Does it have fuel mods?

Now, answer my questions.
What kind of spark plugs and wires are in there?

car has a k and n filter, manual boost controller, and autometer boost gauge. no fuel mods..im not positive on what kind of spark plugs but have heard they BLOWW!!!!
keep in mind i have had the same spark plugs in the car and it ran fine b4?? dont know the problem still..i have the day off tomorrow so im gonna turn down the boost some (try that) and if that doesnt work another leak test.

p.s-gotta love when i post a problem on this site and then MY HEAD LIGHTS JUST SHUT OFF WHEN IM DRIVING ONE NIGHT SHITTT

all for the love of

 

[laserspeeddemon]

I'm betting that either the TB seals are bad or the TB gaskets need to be replaced.

 

[BLampinen]

update for anyone who may have the same problem: you guys all hit the nail straight on the head. i got an SAFC2 and tuned evertything down to -20% at low throttle and -25% at high throttle. no more fuel cut even though i just took it out to the track the other night and was boosting at 23 lbs on 96 octane gas (by mixing toulene and gasoline) .
thanks for all the help
ps. i stilll dont have an afpr and from what i can tell, i dont believe i need one yet because at 23 lbs, im gettting 2050 hz on my karmann reading and with -25% correction on the safc2 im not getting any fuel cut.

 

[steve]

ps. i stilll dont have an afpr and from what i can tell, i dont believe i need one yet because at 23 lbs, im gettting 2050 hz on my karmann reading and with -25% correction on the safc2 im not getting any fuel cut.

There is nothing in what you posted that has anything to do with the need for a AFPR. You would need a fuel pressure guage to see that the fuel pressure at low loads is way over where it should be.

Steve

 

[jkrause]

I just put hks 264/272 cams in and every once and a while when i boost to 18 or higher i get this horrible cut and just seems like i hit a wall. I have no clue what this is but it never happened before i put the cams in and the timing is perfect. Any help is very appreciated

 

[vr6chris]

fuel cut. it is necessary that you now tune the car. different cam shafts, especially the ones you used, need more fuel added up top. if you have a piggy back controller like a safc or whatever, go to the dyno and tune it.

 

[oldman]

Im still hitting fuel cut to this day. I got another TB and it doing the same thing. It wont hold any boost. When Im doing the boost leak test and I open the TB it still hisses out. Even with the "low mileage" TB i just got in the mail 2day.

I have been away for a while, any updates on this?

 

[Boost95]

Yes, I got a new ReMan TB with all new seals and gaskets. The TB no longer leaks but there is still a decent sized leak somewhere. It still wont Hold Boost. The boost will build faster during the test but it still leaks out. It seems like its coming out near the center or the Intake Manifold. I dont know what to look at anymore. I cant see bubbles anywhere. This is annoying On top of my car being a PITA my g/f had trouble with her car yesterday and the tow truck company towed her AWD car 5 miles with just the front wheels up!!

 

[ddavisaf]

Injectors, either the seals or the insulators. Spray them down and test again.

Edit: BTW, you don't mind if I hop in do ya Bruce?

 

[Boost95]

Take a quick view thru the post. They were already replaced.

 

[ddavisaf]

So check 'em again anyway
They may not be seated correctly.

There is no way in hell I'm reading 90 somethings posts on fuel cut issues






Ok fine I'll skim through.

 

[ddavisaf]

Okay, I just read 100 posts on this problem.
Here is what I'm not understanding.

You're hitting fuel cut at 13 psi. Then you're hitting 20 psi.

You tested the actuator, and you said it worked just fine. But it's not opening when you drive the car.

Now here's the good news.
I think we'll have your problem fixed within 20 posts from now.
Update your car profile for us real quick (it'll only take a second.)
And another thing that'll make life easier on all parties would be for you to repost everything that you've done to fix the problem thus far.
As I said, 20 posts.... I have faith.

 

[oldman]

BTW, you don't mind if I hop in do ya Bruce?

Please do, the more ideas the better. I'm just going to sit back and see how this 20 posts commitment will be fulfilled.

 

[ddavisaf]

I have faith

Edit: BTW, PM's don't count

 

[Boost95]

Okay, I just read 100 posts on this problem.
Here is what I'm not understanding.

You're hitting fuel cut at 13 psi. Then you're hitting 20 psi.

You tested the actuator, and you said it worked just fine. But it's not opening when you drive the car.

Now here's the good news.
I think we'll have your problem fixed within 20 posts from now.
Update your car profile for us real quick (it'll only take a second.)
And another thing that'll make life easier on all parties would be for you to repost everything that you've done to fix the problem thus far.
As I said, 20 posts.... I have faith.

So im guessing you browsed thru real fast. If you actually read them you would see I posted every time and what is there to update in my profile. Bruce has been helping me out quiet a bit. If you are in here to complain about stuff , id rather do it myself. I listen to it from my girlfriend all day, I dont need another on complaining. I would love to get it done in 20 posts Its one thing after the other thats why it is so long. Once I fix something another thing goes. I checked rechecked the seals. Im going to go take the car apart in a few to change an ISC motor. When im putting it back togeather I will try to pinpoint it better. :

 

[Boost95]

Now to answer your questions.

Im hitting fuel cut at about 10 psi now w/o that leak near the TB.
When I was hitting 20 PSI that is because the Line to the WG was kinked.
I tested the Actuator arm and it functions properly.
Drove the car and teh arm popped off.
Fixed the arm and all is good.
Replaced Injector Seals
Blocked Off EGR( WAS A BIG LEAK)
Blocked off some vacuum lines
NEW TB & shaft seals + gaskets

That should help bring you up to speed

 

[ddavisaf]

I'm not here to give you a hard time bud. I'm here to help you get your car running.
Bruce is awesome, he's my go to guy. I know that we can get your car running like a champ again. And since we've already ruled out so many things I don't see it taking very much longer. Just remember to attack the problem with an open mind.

Oh, and if you think your girlfriend is complaining now, wait until you're married. Then they KNOW they can get away with it so it gets worse.
Here's hoping my wife doesn't decide to log on Tuners today......

Anyway, back on topic.
You're taking out the ISC and whatnot, then running another boost leak test. Then you're going to try and pin point the leak better and post back what you find right?

Run your boost leak test straight from the TB elbow to pin point the leak near your intake manny better. Once you find that, get her fixed and move back to the turbo inlet and test it again.

2/20