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

 

[Laser-man]

that still doesnt answere my questions, i dont have that kind of money, and its not necessary right now.

 

[SpoOLxExO]

While true that TMO shut down, it's not impossible to get ahold of that EPROM program.
There is a seller on ebay named "MistubishiSpecialties", that sell copys of the program for $90 shipped, you can't go wrong with that price considering the original was $300
But you still haven't said weather or not you actually have an EPROM ecu or not. So, if you dont add another $150-200 for it.
The program will be your best bang for buck upgrade, next to a act2600. And when you put those two mods together, you have a "Launch-mobile"
A logger IS a good idea, but the resources on TMO logger is slim, and pocketlogger is prolly the only choice for 1g right now.
But still tell us if oyu have an Eprom, we'll start there.

 

[Laser-man]

i do have an eprom thats why i was concidering getting a chip, i would not have said that if i didnt know if i had an eprom or not, and i was not planing on getting a tmo loger, i was looking at the one under the parts guide, and i am planning on putting a new clutch and flywheel in soon, any ideas on a good flywheel for the price, i am only pulling my tranny once more for a while i hope and while i am in there i am doing it once and doing it right.

 

[SpoOLxExO]

Yeah if you want some rev-ibility, consider the ACT2600/ACT flywheel combo. They just released it for the turbo DSM. It features a surface, perfectly stepped for the 2600. Plus its only $270 for the flywheel, and around $400 for the clutch kit. Either that or go with your resurfaced stock flywheel and clutch. When I installed the TMO program, and the act clutch. I could chirp 2nd with a stock 14b, and stock exaust at 15psi. So its definately worth the loot.
Check out that ebay deal, I just looked for it, and they're still sellin em lke hotcakes.

SO brief review:
-ACT2600/Xtreme flywheel or stock one
-TMO program chip off ebay
-Palmlogger or TMO laptop if you can find the program.

aside from the clutch, the logger and the eprom chip will definately solve your fuel-cut problem! Hope this helps

 

[SpoOLxExO]

maybe. Seeing he has an eprom ECU, its possible that when Diamond Star Motors were "Tweaking the emissions program" that he got stuck with a bunk chip that was intentionally de-tuned for emissions sake.
LAndo, do you just have a blaha maf? no EProm program? how does it work? got any logs with a blaha and that 20g?

Its alot harder to figure out without the car being in front of you of course.

Let us know how it goes!

 

[LandoAWD]

Yeah, I run the Blaha, no EPROM. Never get fuel cut unless I have intake leaks. I'll post a few logs with my setup in tuning when I get my IRC FMIC on.

Edit: Needless to say, Al's MAF is a huge improvement over stock for not too much cash.

 

[SpoOLxExO]

But you said, Never get fuel cut unless you have intake leaks...
Laser-man your absolutely positive you have no intake leaks, not even the throttle body seals, and the compressor outlet? The intake manifold sometimes leaks...
I'm just saying or the sake of saying
good luck

 

[LandoAWD]

He may just be overrunning the stock MAF. Do check for leaks properly, not visually.

 

[hostile]

LAser-Man, you have no fuel mods in your profile. Get atleast a fuel pump and then your car should run rich enough not to hit fuel cut. The problem is you have too much air and not enough fuel.

You really need fuel control, a fpr and an afc would probbaly take you pretty far.

With just an fpr and a fuel pump you could make your 450's flow like a much larger injector, probably more than enough fuel for anything a 14b can throw at it.

Maybe even pick up a 2g mas since all thoose guys are going to GM mas's you could probably pick one up cheap.

It really depends on what your plans are with the car, and your budget.

 

[SpoOLxExO]

This is true hostile. However no matter how many hard parts you bolt on to remedy the situation, the more variables are introduced. Eliminating his electronic "Gremlins" at this point of the game is more crucial than adding fuel components, IMHO. I know a DSMer who has the same car as I do. last year he managed to run a 12.6@ 106 on STOCK:

-MAF with no honeycomb/ screw backed out.
-Ported 14b
-450cc injectors
-re-wired stock Fuel pump
-Stock sidemount, and upper pipe
-2.5" turbo-back
-act2600
-AFC
-TMO III ECU
-PocketLogger

His car runs soooo well thanks to an ECU that doesn't act like a brat, and a little fine-tuning w/ the afc guided by the datalogger.

I have invested most of my initial mods as electronics that Guaruntee that maximun performance can be attained, no matter what hard-part is bolted on.(TMOIII/VPC/Logger/Nice 60mmEGT/Boost Guages etc..

The TMO mod is crucial when going fast even with the use of a stock MAF. That is why you see sooo many cookie cutter DSM's that these F&F "Newbies" are coming out with. WHat does he have?
-Turbo XS RFL BOV
I dont care what ANYONE says, w/o a VPC, AEM, Or stand-alone, you simply cannot vent your Blow-off valve to the atmosphere. The "Loudness" factor is basically what these guys are going for.
-Walbro255 HP
Although a good flowing pump for the money, it overruns your Fuel pressure regulator everytime.Got to have an adjustable fuel pressure regulator.Is funny how these guys are at like -50% on their afc, and it doesn't lean out enough.Ususally the only fuel mod when bolting on huge "DiscoPotato" Turbos that they definately dont need.
-AFC
This is a very nice piece. However without TMO, or even a Datalogger (Which is a must) fuel tuning is played by ear, and usually doesnt work well enough.

All I do is observe what happens in my DSM community, and thankfully my local club NewEnglandDSM is there to rectify the misguiding associated with "TV tuning". Thanks Leon

Bascally you want:
-No intake leaks
-Good timing advance
-ECU logging to see what is holding you up

Hope this helps

 

[hostile]

You guys are really missing the point, stock fuel +14psi = fuel cut. There is nothing wrong with his car.

It isn't something wrong with his ecu, it is something wrong with his fuel.

Once the mas gets over a certain hz value you hit fuel cut.

If he adds more fuel and takes out some signal form the mas he will be fine at higher boost.

Since he is a first gen the afc II would be pretty good, since it shows knock on the display he could use it to tune.

 

[SpoOLxExO]

You guys are really missing the point, stock fuel +14psi = fuel cut. There is nothing wrong with his car.

Well I have to ask, have you ever owned a first gen?

So fuel cut means theres nothing wrong with the car huh?

It isn't something wrong with his ecu, it is something wrong with his fuel

Were you even reading my post?
that 12.6 run was at 20-21 psi on 116vp , but on his stock fuel pump, injectors, and regulator.

Besides, now your contradicting yourself

First he says:

You really need fuel control, a fpr and an afc would probbaly take you pretty far.

And that would intercept the ECU signal, which controlls the engine btw, and tricks it to behave a certain way.

But then its:

It isn't something wrong with his ecu, it is something wrong with his fuel.

Hmm interesting.
Laser-man has an Eprom ECU
Bottom Line, Get the chip.
Data log
Seal all leaks.
New plugs, fuel filter if not done recently.

peace

 

[Laser-man]

i have coverd everything every one has said in here except the chip and fuel upgrades, i have a hard wired fuel pump, so i am getting a little more fuel than stock. i checked my intake with that boost leak tester off of vfaq time and time again, and it still does not leak. i guess i just need to get a chip and a logger next, thoes will probobly be my next mods, after the 2600 and the flywheel. thanx for the help

 

[90AWDTalon]

Fuel cut has nothing to do with how much fuel your getting. When the ecu see's a preset volume of air it will cut fuel and spark to save your engine. This limit is preprogrammed and can not be changed. Your ecu doesn't know or care how much fuel your getting, once it hits it limit it cuts fuel.

When you upgrade your fuel system and have the ability to safely run higher than this set limit, you have to fake the ecu into thinking your inhaleing less air volume. This is usually done by installing bigger injectors and either a MAFT or SAFC. When you install bigger injectors your ecu doesn't know their bigger, it continues to operate as if you have the stock injectors and you run way to rich. To combat this with the MAFT or SAFC tricks the ecu into thinking its getting less air. This does three things, 1. you have the proper air fuel ratio, 2. your timming gets advanced some, and 3. fuel cut gets delayed. The limit hasn't changed but because the MAFT or SAFC tells the ecu its getting less air it delays its onset.

Read this:
http://members.shaw.ca/costall/ECUprimer/ECU_ch7.html

 

[LandoAWD]

Originally posted by Laser-man
i have coverd everything every one has said in here except the chip and fuel upgrades, i have a hard wired fuel pump, so i am getting a little more fuel than stock. i checked my intake with that boost leak tester off of vfaq time and time again, and it still does not leak. i guess i just need to get a chip and a logger next, thoes will probobly be my next mods, after the 2600 and the flywheel. thanx for the help

If you still have the stock 1g MAF and no fuel upgrades, you haven't covered everything.

 

[Laser-man]

i mentiond i had no fuel up grades except hard wired pump, i forgot to add i didnt do any mas mods eather, except the silencer removal.

 

[GoSpeedRacerGo]

Do they still the Blaha mas? If so where can I get it at? Haven't been able to find it anywhere!

 

[LandoAWD]

PM T6Rocket on here or on talk. Al will make one for you.

 

[SpoOLxExO]

Do the "Free" mods as listed under www.vfaq.com. Should have known better to begin with. Crazy how the simple things distance themselves so much as we quest for advanced knowledge!

 

[Thebeast431]

B12 Chemtool, its a fuel cleaner in a white bottle. When I was hitting fuel cut, at only 12psi, I removed my lower honeycomb on the MAF and haven't hit it since.

Travis

 

[PRESSURIZED]

Laser Man, take out the lower honey comb in your stock mas.

 

[sqhopeful]

Last week I blew a clamp of my FMIC piping. this weekend I replaced the clamp and install new NGK bpr7es (i think that is number, I just asked for ngk plugs for a 91 tsi) and gapped them at 0.028.

after the plugs and new clamp I drove it but did not log it. It seemed pretty good, spool up was a little slower than before so I assumed I still had a little leak and planned to back under the car tonight.

the car sat until today (I have to take to my insurance company, they said they need to take picutres since the car is over 10 years old). I borrowed my work laptop to log it on my to work.

now, the car hits what I think is fuel cut. anytime I go WOT and get over 4k rpms.

It seems I may still have a large boost leak (but when i blew the clamp it would not build boost at all). But since I did the plugs at the same time I am not sure what is causing the problem.

My questions are:

1. does the attached log infact show fuel cut?
2. do think I still have a bad boost leak or is there a problwm with the plugs? the runs seems ok when not WOT.
3. why would the problem show up after the car sat for a few days on not on saturday when i first did the work?

any insight is appreciated.

 

[LandoAWD]

Learn how to quote, boy. Notice the "no fuel mods..." before the portion you quoted.

Go write your tech articles, and notice the rules concerning attacking mods.

Edit: After researching, I was (and have been since day 1) mistaken about a lean condition causing cut.

http://www.dsm.org/how-tos/JFM/MAF_Mod.html

Last sentence.

 

[a351must2]

and I forgot I also had it do that at low boost once when an intercooler hose came loose and would only leak with boost.

 

[boostedinaz]

I have had several issues like this with my car. The only things it has ever been were:

Plugs and wires

Leak in IC piping or pipe off all together

Low voltage

That last has been a PIA for a ahile because I didnt think of it, If you car isnt at 12.8 or higher in volts then you car will miss top end.

Hope that helps

Michael