7mgte fuel cut

[kngofbrknprts]

i hate fuel cut. i have an 89 supra turbo and i have a few questions. how does fuel cut work on these cars and how do you avoid it. if the fuel cut is just a resistor in the computer can it be removed? if not than is there any kind of piggyback system that eliminates it? like a maf translator

[TcmaBoy]

You can find used HKS FCDs (Fuel Cut Defencer) pretty cheap on ebay.

[Jeeves]

If you do not have the supporting mods for an FCD, you should not get one unless you feel like paying for the cost of a rebuild.

FCD's are the cheap way of ruining an engine. Fuel Cut is there for a reason, to save your car from going into a condition which it can't give you enough fuel for.

VPC's will remove it, I don't know if MAF converters will. Personally, I think they're a crock. If you do the proper mods, you won't have to worry about it, but I don't recall what you have.

My $0.02. Do it the right way, don't blow shit up.

[CryoSlash]

Originally Posted by kngofbrknprts

i hate fuel cut. i have an 89 supra turbo and i have a few questions. how does fuel cut work on these cars and how do you avoid it. if the fuel cut is just a resistor in the computer can it be removed? if not than is there any kind of piggyback system that eliminates it? like a maf translator

just get a lexus afm. eliminating fuel cut is the worst thing you can do To your engine. well not the worst but its still bad haha.

[TcmaBoy]

Originally Posted by Jeeves

If you do not have the supporting mods for an FCD, you should not get one unless you feel like paying for the cost of a rebuild.

FCD's are the cheap way of ruining an engine. Fuel Cut is there for a reason, to save your car from going into a condition which it can't give you enough fuel for.

VPC's will remove it, I don't know if MAF converters will. Personally, I think they're a crock. If you do the proper mods, you won't have to worry about it, but I don't recall what you have.

My $0.02. Do it the right way, don't blow shit up.

What are you talking about? A FCD will not ruin your engine. You do not need supporting mods for it either. All it dose is override the safety fuel cut at about 15 PSI. What you do need supporting mods for is the extra boost you intend to run. After all, the only reason to run a FCD is if you intend to raise the boost level. If you don't do supporting fuel mods for the extra air flow then you can blow the motor. Now, if you intend to raise the boost levels in your engine you will need some kind of fuel cut defense, as well as the supporting fuel mods. Otherwise the ECU will kill the engine as soon as you hit the cut point. You will never see higher levels until it is eliminated. Some piggy back units such as the HKS PFC-FCON will provide a fuel cut override. Some don't so you will need some thing like a FCD. Either way you will need it.

[Jeeves]

Originally Posted by TcmaBoy

What are you talking about? A FCD will not ruin your engine. You do not need supporting mods for it either. All it dose is override the safety fuel cut at about 15 PSI. What you do need supporting mods for is the extra boost you intend to run. After all, the only reason to run a FCD is if you intend to raise the boost level. If you don't do supporting fuel mods for the extra air flow then you can blow the motor. Now, if you intend to raise the boost levels in your engine you will need some kind of fuel cut defense, as well as the supporting fuel mods. Otherwise the ECU will kill the engine as soon as you hit the cut point. You will never see higher levels until it is eliminated. Some piggy back units such as the HKS PFC-FCON will provide a fuel cut override. Some don't so you will need some thing like a FCD. Either way you will need it.

Thanks for answering your own question.
He's near stock wanting more boost, nah uh. Good way to cook shit.

[TcmaBoy]

Originally Posted by Jeeves

Thanks for answering your own question.
He's near stock wanting more boost, nah uh. Good way to cook shit.

Right, I just wanted to be clear that it is the extra airflow, not the FCD that cooks the motor. Even with out the FCD you can blow things up on a stock 7M. You can run enough boost to damage the ceramic turbo before hitting the fuel cut. Also, there was no mention of existing or future mods in his post.

[Jeeves]

Originally Posted by TcmaBoy

Right, I just wanted to be clear that it is the extra airflow, not the FCD that cooks the motor. Even with out the FCD you can blow things up on a stock 7M. You can run enough boost to damage the ceramic turbo before hitting the fuel cut. Also, there was no mention of existing or future mods in his post.

The only ceramic CT26's were on Mr2's in Japan and were almost always replaced with steel ones if they were rebuilt.

I've seen CT26's that were grenaded while having shaft play, or poor maintenance, but 12psi is well within a normal, maintained CT26. The only boost level I've seen consistantly grenade them was a guy running 15-16psi through them.

[kngofbrknprts]

i have a 70mm turbo, walbro 255 fuel pump and mass air translator. im not stupid, i know that too much boost is bad, but i think the stock injector should take up to 20 psi, i also have a huge intercooler and i have a laptop on my car that constantly tells me my stats. ive got a MLS head gasket, ARP studs, 40mm wastegate, 2 dsm blov and 3" exhaust. i think the car can take more boost than the ecu lets it. i appreicate the help

[bgrieger]

Glad to see you have many of the various supporting mods...However, feel free to think what you will, but my many years around these cars says stock 440 injectors will not happily deliver enough fuel at 20psi...especially for an upgraded turbo.

Bob

[kngofbrknprts]

what size would you suggest than? i was thinking of 550s but thats only something like a 25% increase. will those be enough?

[bgrieger]

Pressure isn't the real determinant. Power is. I know of very few people that require more than 550's, but you might be shooting higher. Roughly, the limit will end up somewhere around 1hp per cc of fuel delivery, but you start to push the duty cycles of the injectors as you approach the "limit". Every car is a little different, but this is an eyeball point for the 7M.

[Jeeves]

440ccs will not run up to 20psi. Uh uh. Watching my A/F's and such I wouldn't run 'em much above 14 personally, but who knows. You may have better 'luck'. I'll be going with 550s and those will satisfy my goals of 450rwhp @ 5280ft elevation.