Is this Fuel Cut?
Jun 29, 2008, 04:54 PM
#1
Evolving Member
Thread Starter
iTrader: (4)
Join Date: Jan 2008
Location: SF
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
Is this Fuel Cut?
K so yesterday I was at the track and at the end of a big straightaway all of a sudden I lose massive power...My car wont really boost or rev at all high anymore. Ill get up to .5 bar and the turbo will be crazy loud, then itll just fall flat on its face and cut my power...I dunno what it is. all I know is that without boost your top speed is about 79mph, and its not fun to drive a few hours at that slow a speed..I checked my intercooler pipes and everything looks fine..What else should I look at?
Ive got upper and lower intercooler pipes, intake, exhaust, accessport tune, headers, 02 manifold, etc.
Ive got upper and lower intercooler pipes, intake, exhaust, accessport tune, headers, 02 manifold, etc.
Jun 29, 2008, 05:25 PM
#3
No, fuel cut is when you go full boost and hit a brick wall right at peak boost (or when your airflow gets high enough to trigger fuel cut in the ECU). If you can't boost anymore, then you probably blew off an IC pipe - have you checked beyond just looking? It may only be opening under boost, which you wouldn't see at rest.
Do a pressure test and check your MAF/BOV/Intake connections.
Do a pressure test and check your MAF/BOV/Intake connections.
Jun 29, 2008, 08:45 PM
#5
Evolving Member
Thread Starter
iTrader: (4)
Join Date: Jan 2008
Location: SF
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
No, fuel cut is when you go full boost and hit a brick wall right at peak boost (or when your airflow gets high enough to trigger fuel cut in the ECU). If you can't boost anymore, then you probably blew off an IC pipe - have you checked beyond just looking? It may only be opening under boost, which you wouldn't see at rest.
Do a pressure test and check your MAF/BOV/Intake connections.
Do a pressure test and check your MAF/BOV/Intake connections.
Ya thats what I was thinking, but i physically checked everything and it all was firmed up...Ill have to recheck with someone hitting the throttle i suppose.
Jun 29, 2008, 09:00 PM
#6
You cannot even come close to seeing a boost leak by using your hand/eyes unless the pipe is completely disconnected. I recently did a pressure test on my new IC pipes/FMIC that have t-bolt clamps, and there wasn't anything noticeably loose, but I had 3 _major_ leaks where boost wouldn't even build past 2 psi. You absolutely cannot check such things visually. You don't use the throttle to do a pressure test...
Jun 29, 2008, 09:51 PM
#7
Evolving Member
Thread Starter
iTrader: (4)
Join Date: Jan 2008
Location: SF
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
I can get the car up to 5k before it hits the wall and cuts all power, but thats with a very light foot and usually it falls closer to 3k. Looking at the way it happened I dont think it could be a boost leak, much less something I wouldnt notice right away. It was a big blow like an IC pipe blowing off..What exactly should I do for the easiest sort of test?
Trending Topics
Jun 29, 2008, 10:09 PM
#8
boost leak test...trust us man...take it to a tuning shop have them do it for like $60 or whatever it costs in your neck of the woods....cause with a leak test you can pressurize your system to what you run daily...so if you run 23psi daily or whatever, you can test that with your car not running which means you can hear a leak in most cases...then pinpoint it and fix it...turbo cars are very picky...any type of leak can cause **** to go wrong...
Jun 30, 2008, 05:28 AM
#9
Evolving Member
iTrader: (10)
Join Date: Dec 2005
Location: Orange County, CA
Posts: 300
Likes: 0
Received 0 Likes
on
0 Posts
When you say you can hit 5k and then the power gets cut...are you saying that the car bucks or just that power stops building?
I had an issue where I maxed out at 10psi. In the end the dealer replaced the wastegate actuator (I paid), powertrain control module (warranty), and engine control module (warranty). To me they troubleshooted backwards to fix the problem but it did get fixed.
"It was a big blow like an IC pipe blowing off..." - To me the big blow is usually a pipe coming off completely. They're either on tight or blown off all the way in my experience. If you have something completely disconnected I would suspect you'd be running a lot worse.
I had an issue where I maxed out at 10psi. In the end the dealer replaced the wastegate actuator (I paid), powertrain control module (warranty), and engine control module (warranty). To me they troubleshooted backwards to fix the problem but it did get fixed.
"It was a big blow like an IC pipe blowing off..." - To me the big blow is usually a pipe coming off completely. They're either on tight or blown off all the way in my experience. If you have something completely disconnected I would suspect you'd be running a lot worse.
Jun 30, 2008, 06:08 AM
#10
Evolving Member
boost leak test...trust us man...take it to a tuning shop have them do it for like $60 or whatever it costs in your neck of the woods....cause with a leak test you can pressurize your system to what you run daily...so if you run 23psi daily or whatever, you can test that with your car not running which means you can hear a leak in most cases...then pinpoint it and fix it...turbo cars are very picky...any type of leak can cause **** to go wrong...
WarTalon: that is the best description. You will know what Fuel Cut feels like, it feels like the car hits a brick wall, and falls flat on it's face, almost enough for you to be concerned if you broke somthing if you have no idea what it is.
Jun 30, 2008, 02:09 PM
#11
Evolving Member
Thread Starter
iTrader: (4)
Join Date: Jan 2008
Location: SF
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
WTF? $60? I thought everybody did boost leak checks? All you need is an air compressor, or the very least, a bicycle tire pump.....
WarTalon: that is the best description. You will know what Fuel Cut feels like, it feels like the car hits a brick wall, and falls flat on it's face, almost enough for you to be concerned if you broke somthing if you have no idea what it is.
WarTalon: that is the best description. You will know what Fuel Cut feels like, it feels like the car hits a brick wall, and falls flat on it's face, almost enough for you to be concerned if you broke somthing if you have no idea what it is.
Jun 30, 2008, 02:55 PM
#12
Evolving Member
http://www.vfaq.com/index-main.html
^^^^^^^ Click on the link. Go to the "Intake" section, and scroll down and click on the link under "Misc. Intake: Intake Leak Tester". That site was meant for DSMs, but has alot of information that can be applied to even your 4G63, or turbo cars in general.
Basicly, you either need to cap off the turbo completely with a rubber cap with a clamp, or make a cap with a built on air nipple. The first choice is easier to do. Then you either pressureize the system from a vaccum line, or from the nipple on the cap, had you choose to go that route. It helps to have another buddy around to watch the boost guage and see how high the pressure is reaching. If you are struggling to build any pressure, you have a massive leak (ie, disconnected charge pipe, hole in coupler, ect.). If it rises and holds steady or falls very very slowly, you have little to no leaks. If it rises, and falls quickly, you have a boost leak from one or more places.
It is helpfull to have a spray bottle of soapy water around. Spray down all of your charge pipes, around the throttle body, BOV, and the turbo "J" outlet. As you pressureize the system, bubbles will easily show you leaks. You can also hear them as well.
Jun 30, 2008, 04:34 PM
#13
Evolving Member
Thread Starter
iTrader: (4)
Join Date: Jan 2008
Location: SF
Posts: 183
Likes: 0
Received 0 Likes
on
0 Posts
No, fuel cut won't feel like a misfire. It will literaly feel like you hit a brick wall. It's one big BANG, and then nothing. It is unlike a misfire. Fuel cut will make you think for a second if you arent expecting it or know what it is, that you blew up your engine.
http://www.vfaq.com/index-main.html
^^^^^^^ Click on the link. Go to the "Intake" section, and scroll down and click on the link under "Misc. Intake: Intake Leak Tester". That site was meant for DSMs, but has alot of information that can be applied to even your 4G63, or turbo cars in general.
Basicly, you either need to cap off the turbo completely with a rubber cap with a clamp, or make a cap with a built on air nipple. The first choice is easier to do. Then you either pressureize the system from a vaccum line, or from the nipple on the cap, had you choose to go that route. It helps to have another buddy around to watch the boost guage and see how high the pressure is reaching. If you are struggling to build any pressure, you have a massive leak (ie, disconnected charge pipe, hole in coupler, ect.). If it rises and holds steady or falls very very slowly, you have little to no leaks. If it rises, and falls quickly, you have a boost leak from one or more places.
It is helpfull to have a spray bottle of soapy water around. Spray down all of your charge pipes, around the throttle body, BOV, and the turbo "J" outlet. As you pressureize the system, bubbles will easily show you leaks. You can also hear them as well.
http://www.vfaq.com/index-main.html
^^^^^^^ Click on the link. Go to the "Intake" section, and scroll down and click on the link under "Misc. Intake: Intake Leak Tester". That site was meant for DSMs, but has alot of information that can be applied to even your 4G63, or turbo cars in general.
Basicly, you either need to cap off the turbo completely with a rubber cap with a clamp, or make a cap with a built on air nipple. The first choice is easier to do. Then you either pressureize the system from a vaccum line, or from the nipple on the cap, had you choose to go that route. It helps to have another buddy around to watch the boost guage and see how high the pressure is reaching. If you are struggling to build any pressure, you have a massive leak (ie, disconnected charge pipe, hole in coupler, ect.). If it rises and holds steady or falls very very slowly, you have little to no leaks. If it rises, and falls quickly, you have a boost leak from one or more places.
It is helpfull to have a spray bottle of soapy water around. Spray down all of your charge pipes, around the throttle body, BOV, and the turbo "J" outlet. As you pressureize the system, bubbles will easily show you leaks. You can also hear them as well.
Jun 30, 2008, 08:30 PM
#15
WTF? $60? I thought everybody did boost leak checks? All you need is an air compressor, or the very least, a bicycle tire pump.....
WarTalon: that is the best description. You will know what Fuel Cut feels like, it feels like the car hits a brick wall, and falls flat on it's face, almost enough for you to be concerned if you broke somthing if you have no idea what it is.
WarTalon: that is the best description. You will know what Fuel Cut feels like, it feels like the car hits a brick wall, and falls flat on it's face, almost enough for you to be concerned if you broke somthing if you have no idea what it is.
i said for him to get done somewhere cause he seemed lost lol and i had it done just cause i was there about to get tuned and we thought it'd be a good idea since i was having some issues so thats why i said the $60
