Fuel Cut: What is it? How do I fix it? [merged]

[Slanted J]

All fuel cut threads are combined here.

I've tried doing a search but to no avail.

I was just wondering what Fuel Cut is. I've heard it tossed around alot, but do not actually know the details behind it. And, naturally, I can gather that its when the fuel is cut off, but when and why.


Thanx,
Jon

 

[90dsmboy]

If you are running more than stock boost, you should adjust the greddy bov to a harder setting so it will hold more boost. Does you turbo sound really loud? Could be a couple things: perhaps one of your intake pipes bursted/ certain clamp no longer surving its purpose, sounds like a boost leak. Maybe intake manifold might have a leak due to running 20psi for 30 seconds. Hope this info. helps you out.

 

[fwdeclipse]

Ok thanks i will set the bov a little stiffer.I did not run 20psi for 30 seconds.When i did a boost leak test i pumped it up to 20psi and it took more than 30 seconds to leak out.I checked again last night and have no boost leaks.

 

[BoBbOrAzE]

When you switched to your upgraded fuel pump did you reset your ecu by unplugging the battery? I have heard from a bunch of members that this always helps, although I could be completely wrong.

 

[fwdeclipse]

I think I have a similar problem. I switched to my stock 2g bov and earlier tonight to a 1g bov. I reset the ecu which I was told will relearn fuel curves and help. It drove fine so after a little I got on it hard, I hit about 18psi and boom im pretty sure I hit fuel cut (it was 30˚ outside). The sudden slam stop and it cut in and out over and over and I could barely get the rpms up without it bogging down and eventually I limped home at low rpms. Does that make sense for fuel cut?/ fwdeclipse is that how yours felt? Im sure my problem is the new bov actually holding boost and the mbc too high. But so anyways when you switched to your upgraded fuel pump did you reset your ecu by unplugging the battery? I have heard from a bunch of members that this always helps, although I could be completely wrong.

No my car would hit fuel cut,then it would start to go again and just keep cuttin.But if i just drive normal it runs fine.I turned the boost down to 15psi and it runs alot better,but it still feels like im runnin rich or somethin cause it is kinda slugish.I did reset the ecu.I bought a logger and am waiting for it to get here and ill post some logs.

 

[andytalon]

If you got a friend with an safc, ask him to do you a big favor, and let you borrow it. Or best thing to do, just buy it. Install it and set all the setting for it, then run a log and tell us what its like.

 

[Openoner]

what about a fuel cut defencer?

 

[fwdeclipse]

Well i wont beable to buy one for a couple weeks.Could the car run rich with stock injectors.Cause that is what if feels like.The spot right above the muffler is startin to turn black.I should get the logger tuesday and i will log it.

 

[steve]

what about a fuel cut defencer?

As far as I know it does the same thing as the switch did on the early MAFT.

You only have one way to eliminate fuel cut, get a EPROM ECU and either a new chip or DSMlink. Both will remove the trigger or raise it to the point where 99.9% of the people will never hit it.

You can perhaps avoid triggering it by getting bigger injectors and reduce the airflow signal to correct for the difference. Making sure that you don't have any boost leaks helps insure that you don't have more air being counted than your really using.

Steve

 

[Openoner]

im in the process of getting dsmlink ...dsmlink has an option for disableing fuel cut? thats my biggest concern at this moment.

 

[will90Eclipse]

Do 1G N/T's have a fuel cut out after around 5000rpm's Is there any way to eliminate this
Thanks
WILL

 

[Pure92TSi]

I'm gonnna have to say no since there isn't any air actually being forced into the engine that could possibly exceed the capabilities of the stock fuel system. It's all being sucked in by the engine ina a N/A car. Sounds like you got some real problems.

 

[Ultimatedsm]

Its time for a tune up my friend.

1. Plugs
2. Wires
3. Fuel filter

You get the picture right? Theres a lot of possibilites of having those kind of symthoms, but I would start with the basics, do a tune up if you haven't. I can list a ton of parts that can cause that.

 

[will90Eclipse]

Thats true, but it seems like my car starts to slow down around or above 5000rpm's.

BTW I just recently did a tune up, could the ECU be slowing my car down??

 

[Ultimatedsm]

Weak spark, bad plugs, bad wires, clogged fuel filter, clogged catalytic convertor, bad compression ratio, weak fuel pump, clogged fuel injectors, bad o2 sensor (Front) etc. Thats why I said you probably need a tune up .

 

[Pure92TSi]

That dosen't sound like fuel cut anyway. Fuel cut feels like you hit a wall. Maybe the powerband just drops off after 5000.

 

[Ultimatedsm]

yeah, I know he wasn't really talking about fuel cut, forgot to mention clogged intake filter as well.

 

[will90Eclipse]

That dosen't sound like fuel cut anyway. Fuel cut feels like you hit a wall. Maybe the powerband just drops off after 5000.

Thats exactly what I mean, it feels like the powerband drops.

 

[delneroni]

I have a 1990 Plymouth Laser with 550 injectors and 16g turbo, many other mods, see vehicle profile for complete list. All done professionally, I am not qualified to do this stuff. I have a problem which might be fuel cut - when accelerating hard through the gears, the car will sometimes give a huge jerk, almost feels like someone slammed into my rear bumper - then it will recover and keep going. I think the ecu is momentarily shutting down the engine, either because of too much boost or something else. Other than this problem, the car is running absolutely great and is is excellent condition, but I need to solve this and would like to know if it sounds like a fuel cut problem and, if so, how best to deal with it (I am getting boost up to 20 lbs and would like to continue that - I think I read somewhere that if you have too much boost the ecu will shut down the engine?)

 

[nukefission]

Do you have any logs or O2 readings of when this happens? You are likely hitting fuel cut. Since you already have an AFC, and I'm assuming it is dialed in correctly, the amount of signal being taken out is not enough to offset the amount of airflow being metered by the MAS. You can either go the dime store route and splice a potentiometer inline with the baro signal wire and raise the baro that the ECU sees, or you can get some EPROM mods for the ECU (if yours is EPROM) to eliminate fuel cut entirely. The latter is preferable.

 

[delneroni]

Thanks for the response. I have looked into this, and I think I will take your advice about using a modified EPROM ECU. Problem is, my ECU is not EPROM, so I need to get one of those. Does anybody know of a reliable source? I have also had some people advise me to get a DSM Link for programming the ECU, and then I could get rid of the SAFC. That is a little pricey, but may be worth it. Opinions?

By the way, now that I know what the problem is, I found a good writeup here:
http://www.tmo.com/prod/eprom/nolimits.shtml
Does anybody know if this company, TechnoMotive, is still in business? When I tried their phone number, I got somebody else entirely. But if they are not there anymore, why would they still have a website going?

 

[nukefission]

TMO has long been defunct. Some place like Foreignecurepair.com or something like that now takes most of the business that once went to TMO. As for EPROM ECU sources, that's a tough one. Check your local DSM crowd to see if anyone has one, or ebay.

www.dsmchips.com is today's replacement for TMO. DSMLink is a good choice, but if you don't plan on going bigger than the 16G, it may not be worth it.

 

[Quasimondo]

If you can't get your hands on an eprom ecu, sell the 550's for a set of 650's or 660's. With the larger injectors you won't have to adjust the AFC to run so rich and you can stay under the fuel cut threshold.

 

[nukefission]

Yes. Keep in mind though that the bigger injector you go with, the more airflow signal you are taking out of the ECU. With 660s you start reaching a point of diminishing returns when the ECU starts bumping up the timing advance way too much because it thinks are you aren't flowing enough air for it to be a threat to the motor. This can have a profound impact on performance, as you will constantly be struggling with knock due to too much advance. To make matters worse, 1Gs have a timing advance "mound" that they apply around 5000 RPM that bumps it up even more. A keydiver chip can remedy most of these issues.

 

[xucpxeclipsex]

hi.. i was wondering if there was any way that i could eliminate the fuel cut besides buying an hks fcd.. let me know if theres an easier way please.. thanx

 

[pepsi21463]

Buy DSM Link?