Supra falls on its face when floored.

Status
Not open for further replies.

Drake69

Enjoyin' mah ride...
Aug 24, 2009
648
0
16
55
Richmond, Virginia, United States
You guys REALLY need to research this stuff before you get yourselves and others killed.... :3d_frown:

From : http://www.dsmtuners.com/forums/frequently-answered-dsm-questions/186971-what-fuel-cut.html

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 corresponds 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 defenser 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 a 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 DEFENSER.
DO NOT JUST LEAN OUT YOUR AFC TO UNSAFE AFRs.
DO NOT TURN DOWN YOUR 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.
 
Last edited:

Drake69

Enjoyin' mah ride...
Aug 24, 2009
648
0
16
55
Richmond, Virginia, United States
And.... from http://autorepair.about.com/od/glossary/gr/def_egr-valve.htm

What is EGR?

The EGR valve helps your car more efficiently and completely burn fuel by recirculating a portion of your exhaust and running it through the combustion process again. This results in a cooler, more complete burn of the fuel which decreases you car's noxious emissions by prohibiting the formation of some harmful gases.

Pros:

The EGR valve is vital to your car's emission controls.

Cons:

When the EGR valve goes bad, it must be replaced.

Description: EGR Valve = Exhaust Gas Recirculation Valve.

The EGR valve controls formation of noxious emissions.
Rough idle and poor acceleration can be caused by a faulty EGR valve.

Guide Review - EGR Valve

The EGR valve, or Exhaust Gas Recirculation valve, is a vacuum controlled valve which allows a specific amount of your exhaust back into the intake manifold. This exhaust mixes with the intake air and actually cools the combustion process. Cooler is always better inside your engine. The exhaust your EGR valve recirculates also prevents the formation of Nitrogen related gases. These are referred to as NOX emissions, and are a common cause for failing emissions testing. Unfortunately, your EGR valve can get stuck, causing NOX gases to build up. You'll know if your EGR valve is stuck or malfunctioning because your car will experience symptoms like rough idle and bucking on acceleration.

This other article is from Wikipedia... READ IT...

http://en.wikipedia.org/wiki/Exhaust_gas_recirculation
 

Drake69

Enjoyin' mah ride...
Aug 24, 2009
648
0
16
55
Richmond, Virginia, United States
I don't mean to sound like an ass, but removing, adding, or playing with your engine mechanicals without proper knowledge is the common cause for engines grenading, resulting in quick deaths of the car or large amounts of cash being thrown away to correct your mistakes. Before excising ANYTHING underneath the hood, read up on why it was put there in the first place. Just because someone else (or many someone elses...) on these forums do it, it doesn't mean it's the best thing for you to do it in your car.
 

lewis15498

Don't blame ebay cheapass
Sep 28, 2008
1,397
1
0
Raynham, Massachusetts, United States
You owe drake a big thank you for finding all those links and explaining them. I would also add to the EGR comment, that when EGR is in use, your computer reduces the fuel injected accordingly. Since your computer thinks it is still there, it reduces fuel when it would normally be using the EGR system. Of course it is not there, resulting in a lean condition aka kaboom.

A rule of thumb that can be applied to modifying any complex machine:
Unles you know
-what it is
-why its there
-what it does
-how it does it
-what happens if it breaks
-what happens if its malfunctions
-what happens when it is removed
-how everything else relates to it
then you shouldn't touch it.
 

Poodles

I play with fire
Jul 22, 2006
16,757
0
0
43
Fort Worth, TX
The real danger without EGR is the aggressive timing used during EGR operation. Hence why it CAN'T be tuned out properly with piggybacks.
 

supramk3

sleeper
Apr 6, 2009
32
0
0
queensbury
This is all i have to say ive have been through alot with my 7m because of stupid mistakes but these older guys are right do some research i had to i have to find a new egr because i took myne off and tost her away now im looking for the parts i saved i have spend thousands of dollars on my 7m stick with what these guys say and ull be fine i know some of them are total dicks and fuckheads but they get pist because they love there supras and hate when kids go and fuck them up thanks guys dont be dicks to me some of u piss me off
 

SupraDuD3

Banned
Jan 1, 2009
78
0
0
knoxville
wow yes i had no idea ab any of this. yes i should have done my research but i just get freaked out and start asking questions and i thought the best place 2 ask was here. so yes thank you ALL for the feed back. whenever this bitchin snow clears up, i will remove the fcd. And go buy an egr valve. this was a great help so once again thanks! i will let u know how things go
 

lewis15498

Don't blame ebay cheapass
Sep 28, 2008
1,397
1
0
Raynham, Massachusetts, United States
supramk3;1502686 said:
This is all i have to say ive have been through alot with my 7m because of stupid mistakes but these older guys are right do some research i had to i have to find a new egr because i took myne off and tost her away now im looking for the parts i saved i have spend thousands of dollars on my 7m stick with what these guys say and ull be fine i know some of them are total dicks and fuckheads but they get pist because they love there supras and hate when kids go and fuck them up thanks guys dont be dicks to me some of u piss me off

Period, space, space, capital letter.:p
 

smokemkevo

New Member
May 28, 2009
565
0
0
.
I've got a HKS FCD, not n the supra yet, but i was wonderin should i go lexus afm, over it.

Would a FCD be safe with 550's, wideband, afpr, walbro fp, n boost contoller?
 

Poodles

I play with fire
Jul 22, 2006
16,757
0
0
43
Fort Worth, TX
smokemyocum;1503410 said:
I've got a HKS FCD, not n the supra yet, but i was wonderin should i go lexus afm, over it.

Would a FCD be safe with 550's, wideband, afpr, walbro fp, n boost contoller?

No, it was meants to be used with HKS's full suite of piggybacks.
 

SupraDuD3

Banned
Jan 1, 2009
78
0
0
knoxville
Drake69;1503282 said:
They're just jealous of your Supra and want to try and help you blow it up.

ya the weird thing is that they have the same thing as i have except bigger turbos and one is running a MINES ECU. so o well! lol
 

kamikazemkiii

Active Member
Mar 21, 2009
1,219
0
36
North Carolina
smokemyocum;1503410 said:
I've got a HKS FCD, not n the supra yet, but i was wonderin should i go lexus afm, over it.

Would a FCD be safe with 550's, wideband, afpr, walbro fp, n boost contoller?

Sell the FCD, add the 550's, lex afm and your other things then you should be happy. The 550's and afm will allow you to run a few more psi.

Id rather have my motor than a few more psi, Ive learned the hard way.
 

smokemkevo

New Member
May 28, 2009
565
0
0
.
k, sorry for thread high jackin but i was also wonderin why need both a safc and afpr? with 550, n lexus afm. could u go without the afpr?
 

dbsupra90

toonar
Apr 1, 2005
2,374
0
0
indiucky
i always use an afpr. i tune to get the a/f flat with the afc, then adjust the entire fuel curve with fuel pressure. another good thing about using the afpr, it will not effect timing like an afc will. hey and you are in bardstown?
 
Status
Not open for further replies.