Fuel cut???

[coryd21]

Im not sure if this is fuel cut or what. I can run my car to 7k and build boos the whole time, but when I shift to 2nd it will only build boost until 5k and it only goes down from there as I go up in my gears. I only have stock injectors and I don't have a fmu yet. So what are my possible problems and how can I fix them??

 

[Boost92awd]

First off what turbo and how much boost? Stock fuel pump? A logger would beable to tell you exactly what your car is doing. Does kind of sound like fuel cut, does it feel like your hitting a brick wall?

Start by doing a boost leak test.
Check your plugs and wires.

 

[coryd21]

Its a t3/t4 turbo from JDM Sport. Yes it fells like I hit a brick wall when it gets to the point of not building boost. What has me really confused is the fact that I can run it all the way through first gear but it won't build boost through the rest of them. I have the stock fuel pump and I'm hitting about 8.5lbs of boost right now. What is a logger??

 

[JEFFREYCASTGSX]

First off what turbo and how much boost? Stock fuel pump? A logger would beable to tell you exactly what your car is doing. Does kind of sound like fuel cut, does it feel like your hitting a brick wall?

Start by doing a boost leak test.
Check your plugs and wires.

Keep in mind that this is a 420a not a 4g63. As for the diagnosis, we need to no more about your setup(your profile doesnt say anything about a fcd or fmu).

 

[coryd21]

I do not have a fmu right now or a fcd. I looking into a good one right now and im just wondering if its as simple as those two things to fix my problem.

 

[JayRolla]

Also remember fuel cut has nothing to do with injectors, pump or anything fuel related. Its when the maf is overrun and the ecu cuts the fuel to save the motor. If you have huge boost leak and the maf is in front of the turbo the turbo works harder and pulls more air overunning the maf. What maf are you running, 2g?

 

[shoobaah]

Hi this sounds extremely similar to the issue i am having, i have a 95 talon tsi awd, i can build 16lbs of boost easy in 1st gear and i can only build progressively less boost as i go up in gear, then it just feels like i slammed on my brakes. i have a small 16g 190rewired 650cc apexi neo stock smic, ngk plugs and bosch wires. good luck coryd21 as it seems we have similar issues

 

[coryd21]

yes it is a stock 2g maf. I'm pretty sure that I don't have a boost leak but I am have problems with my number 1 and 3 cylinders. I changed the plugs and when I got them out they had oil on them. Now the valve cover gasket looks to be missing a bit from the view of the plug holes, but could it also be my valve guides.

shoobah have you fixed this problem that you are having?

 

[JayRolla]

Come on guys dont say "I think I dont have boost leaks". Do a test. Fixes 80% of fuel cut issues if thats what actually is happening. Now that you say there is oil you may be getting a misfire from that leak valve cover gasket.

 

[shoobaah]

Unfortunately no, i havent been able to fix this problem since i bought the car in late april. When i bought the car it had stock fuel system and a 16g turbo. I swapped plugs (my plugs are gapped .027) and wires 190fp just got 650cc injectors and an apexi neo. I Still have the same issue. One interesting thing I may add is that when I originally purchased the car, it wouldnt even boost in first gear, it would still hit the "cut" though it seemed more like a misfire. When i changed the wires it helped; I could build full boost but it would still cut after two or 3 seconds of full boost. occasionally at WOT I can see my gauge holding boost but i dont accelerate, it feels very stagnant. other times it boosts temporarily and then it feels like i slammed on my brakes. I am buying the punishment racing FMIC tomorow and when that comes in and gets installed i am doing a boost leak test to rule that out. Hopefully it is just a boost leak.

 

[coryd21]

well im going to do a boost leak test and I hope that that is the problem, but im probably going to get new plugs and plug wires and a new valve cover gasket just so I can rule those things out or either fix it. The car pulls super hard in first and i want to see how it does through the rest of the gears bc even though its the 420a motor it seems to have a little bit of potential.

 

[the_mork]

It could also be that you are just outflowing your turbo. This happens all the time with nearly stock 2g turbo cars because the t25 just doesn't flow as much as the engine can with a couple small mods. Maybe your turbo is also too small.

Do you have a wideband? Have you changed your AFPR to a 1:1 rising rate unit? If not you are going leaner as your boost increases.

 

[coryd21]

Well i turboed my rs and i have a t3/t4 50trim turbo for it. no i do not have a wideband.

 

[LD25Delta9]

STOP WITH THE MAF POSTS!!!! HE HAS A NT!!!!! NO MAF!!!! to the OP: You have a Manifold Aboslute Pressure Sensor. Our cars read a negative vaccuum from the MAP and if it reads any boost you'll get fuel cut. Some (very rare) NT's have been known to ignore boost signals and run properly, however, it sounds as though yours is being picky. You need either a Fuel Cut Defender or a Missing Link. I recommend getting a FCD from Velicta Paola on this forum. You also HAVE TO HAVE A 12:1 FMU. Your stock FPR can't handle the fuel pressure flucuation so that's also another problem you're probably having. Start with a FCD and get a 12:1 FMU. put those on CORRECTLY then try a couple of pulls and let me know how it feels..

 

[rstare]

STOP WITH THE MAF POSTS!!!! HE HAS A NT!!!!! NO MAF!!!! to the OP: You have a Manifold Aboslute Pressure Sensor. Our cars read a negative vaccuum from the MAP and if it reads any boost you'll get fuel cut. Some (very rare) NT's have been known to ignore boost signals and run properly, however, it sounds as though yours is being picky. You need either a Fuel Cut Defender or a Missing Link. I recommend getting a FCD from Velicta Paola on this forum. You also HAVE TO HAVE A 12:1 FMU. Your stock FPR can't handle the fuel pressure flucuation so that's also another problem you're probably having. Start with a FCD and get a 12:1 FMU. put those on CORRECTLY then try a couple of pulls and let me know how it feels..

Lol, thanks you Delta.
Guys please read what the OP has before you start addressing his issue.

Delta hit it right on, though.
You will know if you hit fuel cut, it'll probably result in a shaking of the car, and you being thrown around in your seat a little. To me, it basically felt like hitting the rev limiter, just slightly more violent.
Without the 12:1 fmu you're not getting enough fuel. So, even if you did have an FCD you would be bogging down because your AFR's would be so lean.
Like Delta said, get an FCD and a 12:1 FMU and go from there.

 

[Locke]

So, you just threw a turbo on your NT and started boosting around, with no fuel mods at all?

Like Delta said, get an FCD and a 12:1 FMU and go from there.

Don't boost until you do this - you may have already damaged your engine, boosting without fuel.

 

[coryd21]

Thank you. That finally answers my questions. I had a pm sent to me about a 10:1fmu would that work??

 

[Locke]

Prefer the 12:1.

 

[coryd21]

why is that?? Because isn't it 10lbs of fuel pressure for every 1lb of boost and 12lbs of fuel pressure for every lb of boost.

 

[LD25Delta9]

Yes and you need the amount of fuel the 12:1 runs. The 10:1 won't give you enough at certain boost levels.

 

[JEFFREYCASTGSX]

Keep in mind that this is a 420a not a 4g63. As for the diagnosis, we need to no more about your setup(your profile doesnt say anything about a fcd or fmu).

No one listens to me.

 

[kergilman]

No one listens to me.

He also needs a fuel pump that will provide the fuel pressure needed for boosting...(the stock one only provides about half of the needed pressure)