Random Fuel Cut? or Serious Problem?

[Generation1JeY]

Alright guys maybe a month ago after i put my rnr 3" o2 eliminator exhaust on my car it has just been getting worse and worse with fuel cut. I just got my car running tonight after being dead for a week and a half from a busted alternator. I get everything running and its all good, only problem is in 2nd, 3rd, 4th, and 5th gear i cant get passed 4k without being bombarded with fuel cut.

It happens like this, i floor it, the turbo spools up and my car pulls hard as hell, once the turbo spools up all the way and my car hits its true power band, it just starts to hit fuel cut really fast and backfire. It almost always happens at 4k rpms if that makes any sense.

I have my boost controller set at 15-16 psi with maybe a little creep when downshifting and what not, but even when i'm hitting fuel cut i'm only at 15 psi. I'm gonna try taking my boost controller off and running stock boost levels to see if i can hit high rpms without it ####ing up.

My mod list is up to date, but for those who are too lazy:

-stock 14b turob
-2.5 uicp w/ turboxs bov
-ported 2g manifold
-3" o2 eliminator full turbo back w/o cat

I'm just not sure on what could be making it hit fuel cut so fast. Before i got my exhaust i could run it all the way to redline with full 15 pounds of boost and no problems whatsoever. But ever since i had my exhaust i have been having problems with fuel cut.

Any suggestions greatly appreciated...

 

[anconover]

stock untouched mas? stock fuel? whats it creep to when it fuel cuts?

 

[Generation1JeY]

stock mas, with lower honeycomb removed right when i got the car and ran perfectly fine until maybe a month ago, stock fuel system, and i'm not completely sure on what it creeps to, infact i cant even be sure that its holding at 15 psi right now, cause it just starts to hit fuel cut at 15 psi but it looks like it might wanna go higher so i'll go with stock wastegate tonight when i take it for a drive and see if i still have the same problems with stock boost levels. But the boost will probably never creep past 18, ever since i got my exhaust i have had my eyes peeled on the boost gauge and its never passed 18.

 

[fooked]

I have a hard time believing that it's fuel cut at only 15 psi. I would check for boost leaks first off. It's easy to do, and save you a lot of work in the long run.

Definitely try running stock boost levels and let us know what happens.

 

[1fast97gsx]

check plugs and wires ... my car did the same thing before and a new set of wires fixed it.

 

[CanadianTSi]

Yah it could be your plugs and wires or a boost leak. True Fuel Cut feels like slamming into a wall.

 

[thegreatms]

True Fuel Cut feels like slamming into a wall.

True, I thought i blew up my motor when i first hit it. I think many people miss-diagnose fuel cut. It seems unlikely to be happening at 4000rpm and ~15psi., with the lower honeycomb out. Your just not flowing enough are to hit it. Do you have a logger? what is your htz value right before this happens?

 

[Generation1JeY]

alright thx for all the replies guys i'll get on those plug wires as soon as i can cause i havent replaced those since i bought the car so those could be the problem.

Anyways for the update last night i turned my mbc all the way down and my boost stays at 11 psi, and i can run it all the way to redline

So basically whatever is happening its happening between those 4 pounds of boost.

For the explanation of what its doing, for all i know its fuel cut, but i mean i could be mistaken, all i know is when i hit 4k rpms and full boost the car just doesnt want to accelerate anymore and makes the fuel cut sound where the engine just completely stops for a split second. On really cold nights when i used to drive my car if i punched it all the way i would get a little bit of fuel cut, i mean its just like a pop sort of and it doesnt sound good, i wish i could explain it better but its just like the car shuts off for a second.

Also last night when i turned my boost down i filled my car up with gas cause it was nearly empty, and my friend said that he knew this guy that was hitting fuel cut when he just had a low amount of fuel in his fuel tank... I'm not sure i can believe this cause i dont see how it could matter but 4 psi isnt that much of a difference and right after i filled up with gas my fuel cut (or whatever it is) stopped.

 

[thegreatms]

here is a good website on fuel cut:

http://www.tmo.com/faq/diagport/970929.htm

one part reads:

"I am getting something that feels like fuel cut, but the car only has a slight hesitation, not a dramatic on/off.

Here are three possible reasons for fuel-cut like hesitation. Keep in mind that none of these involve the ECU directly.

1. Lack of spark. Under high boost conditions, if the spark is weak due to dirty plugs, it can be completely blown out. If the spark plug wires are old, the insulation might be breaking down, letting the spark arc to the engine instead of firing in the cylinder.
2. Lack of fuel. Fuel filter or fuel injectors could be clogged. The fuel pump might not have enough output to handle your fuel load. Sometimes, simply running an extra heavy gauge wire to the fuel pump can overcome voltage drops that occur when the pump is drawing a lot of current.
3. Modified MAF. If you have removed the honeycombs (they produce a laminar airflow) from a DSM MAF, you can disturb the phenomenon by which air flow is counted. If the MAF is missing air counts, the ECU will not put out enough fuel to properly match the air the engine is getting. This can cause a lean condition."

maybe your fuel pump is going out. the little extra pressure from a full tank is helping the pump put out enought psi. have you done the rewire?

 

[LA97GST]

I had the exact same problem. The solution is run a few tanks with fuel injector cleaner in it. Clogged injectors suck. When our boost is at 15 psi the clogged injectors arn't being able to squeeze enough fuel through to manage that boost level. That is my theory. All i know is i cleaned my injectors and I no longer have that problem.