ok i put turboback exhaust on today (dc sports downpipe that skips cat, and greddy evo2) and now the car hits fuel cut??? it didnt earlier when i first got on it, but just no (2am) i went and drove it and it fuel cut like 5 times, in 2nd and 3rd gear around 5000 rpm. i was gonna do either a reflash or safc2 anyway but now i guess i'm definitely doing it. i think i just need to lean it our a tad cuz the duty cycle is getting maxed out. or I could just bypass the fuel pressure solenid thats inline with the reg-intake vacuum hose and that would just eliminate it. maybe its boost cut??? i had good luck with my tsi awd with a safc on stock turbo so i hope that will do the trick, did anyone else have this problem???

mods are:

turbo back exhaust
intake
mr bov

i do not have a boost gauge in the car but i havent installed my boost controller yet either. and i do not have a check engine light either, even after i hit fuel cut

any insight would be greatly appreciated.

 

Hi,

I had ongoing problems with hesitation/fuel cut/misfire at ~4500 rpm or so for some time. It's worse when it's cold, since there is more 02. No cel either. Tried leaning with SAFC and it would help to some extent. I went from stock plugs to Denso Iridiums and it got worse over time (gapped at .028). I switched back to stock plugs and installed Samco hoses and the problem went away, for awhile.

Anyway, I recently switched to NGK copper plugs and reduced the gap to ~.025/.026. No more problems for the past couple weeks, even with the colder weather. I think it was misfire, and the problem would be worse if boost was set too high and it was cold out.

Oh well you don't list an MBC, but I think a tbe gives you a little more boost.

Good luck,

FB

 

Yeah what your describing is similar to some trouble I had when I first got my exhaust over a year ago.. I thought it was fuel cut but I think its actually a misfire.. I went to a colder plug gapped tighter .025 and it went away..

 

i know what fuel cut feels like. it feels like i hit a brick wall.

put it this way i was driving in 2nd gear and had my hand just barely resting on the shifter. when it hit, my body jerked enough to push the shifter out of 2nd gear and the car revved up. def fuel cut, but yea i have no boost controller

 

what you are describing is what boost cut feels like and a lot of people call it fuel cut also. you should install a boost gauge and check out the boost. interesting that you can boost cut w/ just a turboback and no cat. even more interesting you can hit it in 2nd/3rd gear. It would take more mods (ie boost controller) than that to hit boost cut if you had a 03-04 evo and usually will hit it only in higher gears too. install a boost gauge and report back your peak boost if you can.

 

Hey all,

Jack, I remember your posts about this issue, glad you got it squared away as well. It's so nice to drive my car and be able to floor it around 3-4K rpm without waiting for that stumble.

Oh well, maybe nolimit has one of those EVO freaks that makes lots of boost with the stock solenoid?

Good luck,

FB

 

I keep hearing the words "boost cut" and believe it is being confused with Fuel Cut. As far as I know, there is no "boost cut". Fuel cut occurs at 1700 Hz Karman value at 20°C and 1000 mbar atmospheric pressure approximately and results in an immediate cessation of fuel and spark. At least that is my understanding.

Speedlimit.....

 

boost doesnt cut it tapers down.it could be a mis fire or fuel cut due to cold weather where the boost spikes to fast for the fuel to comprensate.either get the ngk plugs or an mbc also just to have a set boost on cold temps.

 

The fuel pressure solenoid shouldn't have anything to do with your problem. The FP solenoid helps your car on warm starts. After you drive your car and park it, the heat from your engine bay warms up the fuel in the fuel rail which makes the fuel pressure go through the roof. The FP solenoid helps bleed this pressure off to give you a smooth warm start.

 

yea this is my own personal car so i need to take care of it. i'm gonna put a boost gauge in soon, and get the car dyno'd and flashed at turbotrix

 

I have the same experience with fuel/boost cut but only in 4th and 5th gear. I have an safcII, MBC, HKS RS, and a turbo back with cat delete. My boost goes to about 18 psi in 3rd and I turned it down slightly so it only hits 19 in 4th and 5th and I still get the fuel cut. WOuld a new fuel pump solve the problem or will the colder closer gapped plugs do the trick. I really don't want to turn the boost down anymore. Also, if I got a flash to take off the boost limiter, would that help?

Thanks!

 

i would think you can just lean it out a little with the safc2 to eliminate the fuel cut. i gotta get a boost gauge in the car

 

Hi,

In my experience fuel pump didn't help, I have the walbro.

Leaning SAFC helped to a point, but my case seems more like misfire. The plugs did help me, but YMMV.

Take care,

FB

 

With an upraded fuel pump, you should also get an adjustable fuel pressure regulator and a fuel pressure gauge. Most likely, overrunning your stock FPR is causing your driveability problems.

 

Hi,

Regarding overrunning the stock FPR, perhaps, but my car has been running great for the past two weeks with the tighter gapped NGK copper plugs and a little less boost, even with the colder weather here in New England. I don't notice signs of excessively running rich (well even richer than normal EVOs), such as a lot of black soot on the bumper. I did foul a set of Denso iridiums and the stock plugs did look a little rich as well. Haven't checked on the NGK coppers since I installed them, but at least they're cheap. I'm running stock heat range now, but have a set that's one range colder that I was going to run in the warmer months next year.

Take care,

FB