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

 

[chanley talon]

Have you adjusted your throtlle position sensor latley? I have seen that happen where we changed the stock intake to a fhr racing intake we didnt get the tps set right and we had cut at around 16 . We tried everything thing . Finally we checked the adjustment on the tps sensor and sure enough it was way off . Lined it up right and it was gone.

 

[daren_p]

I see you also have 510 injectors & an safc. If these are installed and adjusted correctly you should be able to boost higher then a "stock" car because of the negative correction from the safc. I would say something up as you shouldne be hitting fuel cut at 16 psi with that setup.

 

[steve]

Your datalog will tell you if you hitting fuel cut vs some other problem.
If the TPS is saying the the throttle is WOT and the IPW is 0 then your hitting fuel cut.

Steve

 

[steve]

Bad news there is no rev limiter on the 1g's

Sure there is.

Steve

 

[2DaTrakNow]

Theres a rev limiter, but not a speed limiter! Try doing a nice toasty burn out, thats the easiest way to hear your engine stop when it hits the rev limiter. Unless of course you have AWD, but just hold it in a gear for a little while.

 

[awd93talon]

well i will check for boost leaks today and check the tps, but im pretty sure there good. I dont have the afc in right now because i have hade some many problems with tuning i took it out, I just now got it to pull all the way throught the rpms without any knock or studder at 14psi but if i turn the boost up to 16psi it feels like fuel cut. I have lower honeycone out too.

steve i dont see on the logger where it has ipw?

 

[awd93talon]

i figured it out the pcv was leaking and few other hoses were leaking, pulls fine now thanks guys.

 

[billys90tsi]

Ok i want to apologize about my statement about the rev limiter. I have had my rpm over 8200 and nothing . thats why i said there isnt one sorry for the dumb comment.

 

[fel1979]

Hi,

My friend has a 1G 91 DSM with ECU without EPROM, running a hybrid turbo, comp cams, Front mount intercooler, forjed internals and 1000cc injectors and SAFC.

The main problem was, we hit the dyno and somehow I cannot go further to 17 psi and 5600rpm without the fuel or MAf cut.

Someone told him that with a MAF translator and a 3,5 MAF from GM will solve the cut problem. Is this correct or still we'll face the same problem again?

If not what should I do to remove the MAF cut?

Regards
Felipe

 

[luvmygst]

I may be wrong bit I would think you need to get someway to compensate for those injectors. Like a chip, or LINK. The biggest injectors that you should run with a SAFC is like 750cc. Since the MAFT compensates just like the SAFC I dont think it would fix the problem. I would start with a E-prom and a chip. I may be wrong but that is where I would start you are probably maxing the SAFC out. Good luck.

 

[exile]

I think the best solution to your problem would be DSMLink, it appears to have the solution to making that car 1 heck of a beast.

 

[fel1979]

I think the best solution to your problem would be DSMLink, it appears to have the solution to making that car 1 heck of a beast.

However for him to use the DSMlink, he will need to purchase a new ECU with EPROM or do the DSMlink can be installed on non EPROM equipped cars?

Regards
Felipe

 

[luvmygst]

However for him to use the DSMlink, he will need to purchase a new ECU with EPROM or do the DSMlink can be installed on non EPROM equipped cars?

Regards
Felipe

Ecu+ can be installed on a car without e-prom. It is still a piggyback(a very advanced one) It should fix the problem, but im not sure if even it can compensate for 1000cc injectors without a chip.

 

[fel1979]

Ecu+ can be installed on a car without e-prom. It is still a piggyback(a very advanced one) It should fix the problem, but im not sure if even it can compensate for 1000cc injectors without a chip.

I just checked in DSMlink website, and the ECU that my friend has, does not have the capability to install the DSMlink on it

It seems that the only thing that have last for him is to install a ECU with EPROM with a DSMLink, am I right?

The main problem is that here in Brazil it's not easy to find one, and it's also far from cheap, it costs something around U$ 1000.

Regards

 

[steve]

The only way to remove fuel cut is to use a EPROM ECU with new software. All other "solutions" either change the trigger condition where you hit it or risk your engine by capping the airflow metering below the trigger.

The old MAFT with the fuel cut switch capped the output. They have since realized what a bad idea that was and removed the "feature".

Steve

 

[94EclipseGST]

^^^Yes, what he said.

Also, my new advice is to forget the MAFT and just get a chip or dsmlink.

I've been away for almost 8 months because my car has been running like crap. I just couldn't tune with the MAFT (no a fault of the MAFT). I pulled the MAFT out just yesterday and put back my stock mas and the old girl pulled so hard I almost crapped my pants.

 

[Jeff822]

Ok, i used to have a 3" turboback on my car but it was creeping really bad to 23 psi and i would get a bad fuel cut, so i put a 2.5" turboback on and now it spikes to 18 psi and when i floor it i get a fuel cut, my car is automatic with the stock T-25 still, idk what it could be, i have a evo o2 housing that i have to put on still and a new o2 sensor that i still need to put on, idk if any of this could be causing it or if venting my bov could cause it, thanks.

 

[No_Skillz]

Fuel cut means the car thinks (correctly or incorrectly) that there is too much air and it can't supply enough fuel. One of the most common problems for this is boost leak. Try a boost leak test and let us know what happens.

 

[fastalon82]

If your running pump gas and your boost is spiking at 18 psi then it probably isnt fuel cut but rather just popping and backfiring from running too lean. My suggestion is to put back on the 3" exhaust, pull off the turbo and buy a 34mm flapper from slowboy, port the hell out of the flapper hole and put the new flapper on, port and put on the evo O2 and that should stop it for the most part. Also, check all your vacuum lines for leaks. Especially the ones going to the wastegate.

 

[JayRolla]

Turn your boost controller down. Thats way to much boost for a stock t-25. The turbo is blowing hot air and most likely your knocking like crazy, which will slowly kill your motor. Also he has a t-25, so why do all that work to that crapy turbo that shouldnt be creeping anyways. My guess is you have a boost leak.

 

[fastalon82]

who's to say he wants to upgrade right now. He has to do something to control his boost. Thats why I said to port everything, now if he just has his boost cranked up to 16 psi or higher on pump gas and a baby turbo then he's just asking for problems.

 

[GSTdude06]

it would be a bad wastegate causing the high psi..... mine was messed up on my 14b and it went to 23+ now I got a working one and it is set at 15 no higher no lower.....

 

[Jeff822]

I have the greddy profec 2 boost controller and its set all the way down at %99. I plan on doing a evo 3 16g in the near future hopefully by the summer time or in the summertime.

 

[No_Skillz]

You also mention boost spike... how is your mbc hooked up?

 

[Jeff822]

You also mention boost spike... how is your mbc hooked up?

Its the electronic greddy profec b spec 2 boost controller, i didnt hook it up my local shop did