Fuel cut/ explanation

[SavageMotors92]

So I recently bought a 98 gst with 158,000 for 2 grand.

Also has a 3 in cat back exh. And cold air intake.

Im thinking my exhaust is too big an may not be creating enough back pressure to equalize the turbo intake/exhaust..? Turbos are new to me so idk....


So I do have an O2 that needs to be replaced, but while im driving in any gear then floor it. The boost will go up to 15-16psi and the fuel cutoff activates....

I can stop the cutoff by slowly pressing the throttle and controlling boost..

Im not trying to repost but nobody has any legit answers for this type of issue..

Thanks for any contributions....

 

[awdtalon4451]

You havent read enough then. This has been covered dozens of times if not hundereds. Use the search button before everybody flames you. A quick search yielded this. Courtesy of Crankbender

WHAT IS FUEL CUT?Fuel cut is actually a removal of the the injector firing signal from the ECU. This is to say that your engine computer doesn't put fuel in the engine, hence the name.WHAT CAUSES FUEL CUT?#Despite the rumors of fuel cut being caused by too low of#fuel pressure, too small of injectors, high flowing exhaust, high flowing intake, or large turbos fuel cut is not directly caused by any of these. Fuel cut is actually caused by the ECU seeing more air entering the engine than it was originally programmed to use. This likely cooresponds with an injector duty cycle which is unsafe or unattainable. So basically fuel cut is caused by the MAF seeing too much air. Don't ask what too much air is....WHY DO WE GET FUEL CUT?Since fuel cut is caused by the ECU seeing too much air we get fuel cut by increasing the air flow through the MAF.#WHAT CAUSES TOO MUCH AIR TO BE SEEN BY THE MAF?Many things can cause this. basically anything you do to the engine to make more power increases the airflow...way to many to list here.SHOULD I GET RID OF FUEL CUT?NO NO NO NO NO...Do not use any device to eliminate fuel cut. Fuel cut is there for a reason. If you are hitting fuel cut the ECU believes that you are moving more air than the#fuel system#can safely deliver. If you are having to eliminate fuel cut with some sort of defender either you have an inadequate fuel system, inadequate tuning tools, or a leak somewhere.WHY DO LEAKS CAUSE FUEL CUT?Since fuel cut is caused by air flow and not actual AFR lost air can cause fuel cut.SO HOW DO I PREVENT FUEL CUT?This really isn't that hard. You have to SAFELY reduce the air the ECU sees. This means to deliver more fuel to the engine (assuming you are shooting for the right AFR) per air count. To do this you must increase the injector size (fuel flow per air count) and then use an new ECU program or AFC to decrease the air count accordingly. Not going to get into tuning now.WHAT SHOULD I NOT DO TO PREVENT FUEL CUT?Do not decrease air counts without adding more fuel per air count. This will cause you to just run lean all the time and cause exactly what fuel cut tries to prevent. So....DO NOT PUT IN A FUEL CUT DEFENDER.DO NOT RUN A 2G MAF ON A 1G WITHOUT A WAY TO BALANCE IT OUT.DO NOT JUST LEAN OUT YOUR AFC TO UNSAFE AFRs.DO NOT TURN DOWN YOUR GM MAFT TO UNSAFE AFRs.DO NOT TRY AND PUT IN LARGER INJECTORS WITHOUT FUEL MANAGEMENT.DO NOT TRY TO UP THE#FUEL PRESSURE#WITHOUT FUEL MANAGEMENT

 

[WES_393]

Here's all the answers for how/why fuel cut happens:
http://www.dsmtuners.com/forums/frequently-answered-dsm-questions/186971-what-fuel-cut.html

But it sounds like you have a boost leak or your boosting too much for your injectors. A high flow exhaust will not cause fuel cut.

 

[awdtalon4451]

Here's all the answers for how/why fuel cut happens:
http://www.dsmtuners.com/forums/frequently-answered-dsm-questions/186971-what-fuel-cut.html

But it sounds like you have a boost leak or your boosting too much for your injectors. A high flow exhaust will not cause fuel cut.

^^+1 I forgot to mention this, thanks Wes

 

[Tyeler18]

The 3" could be causing boost creep, which would cause fuel cut. Or you have a boost leak, like mentioned above which will also cause it. If you want some help with it, or someone to look at it shoot me a PM. I'm like 15 minutes from Chandler.

On a side not, on a turbo car you cannot have "not enough" back pressure as long as it's post turbo. The more free flowing the exhaust after the turbo is, the better. You could run open o2 housing and that would technically be the most effective power-wise.

 

[SavageMotors92]

Hey guys, Thanks for the information. Well I ended up solving this fuel cut. it was a bad 02 .

Now my Wideband A/F Gauge works... it bounces back and forth like it should.. It also ran much better.

Last night I washed and waxed my car and went for a drive. I go to take off for work this morning and I get to the road where I can hit a little boost.

Well Ill hit about 9-10 psi and it will cut out and start sounding like a WRX, I am able to drive it in vacuum - 0 boost but once it builds boost it cuts out and starts sounding like a WRX.... ( In any gear )

I have searched the forums and looked for similar problems... So dont reply telling me to look and search or use the search bar.... I know how to use a forum, Thanks. R


Ya Tyler.. It would be cool to meet up, even just to talk car. Would you happen to have a boost leak tester?