Fuel Cut disable/delete??? ST185

Selsvik

New member
im having trouble with finding out how to disable the Fuel Cut on my 91' ST185. i have a Fuel Cut Defender, but im not sure where to install it... i would be so glad if someone could show me in photo where to mount it.:)
 

Selsvik

New member
thanks for the reply! :) But isn't there an easier way to to it with some of the hoses that goes to the pressure sensor?
its just that i dont know exactly what hoses to connect to. btw, i have a turbosmart FCD :)
 

underscore

Well-known member
It's posted up in several places, but you just disconnect the hose running to the MAP sensor and plug it. This will disable the stock (useless) boost gauge as well.
 

alltrac801

New member
The MAP sensor bolts to the firewall and has a vacuum hose on the bottom side of it. If you google ST185 MAP sensor you should be able to get an idea of what it looks like. If you still cant find it let me know and I can send you a picture.
 

EvilStig

New member
I installed the FCD box on mine recently and have pics from then.



This is the MAP sensor. Fuel cut happens when the voltage returned by the MAP sensor on one wire reaches 4.4 volts. The fuel cut defender works by reducing this voltage by a particular amount so the ECU reads a lower voltage than the sensor puts out. It's effectively a variable resistor.

Fuel cut is an important safety feature and I would not recommend disabling it entirely. You could blow your engine or manifold if you exceed around 15-17 PSI without supporting mods.

You will absolutely want an aftermarket boost gauge at least so you can keep an eye on your pressures.

More info on fuel tuning here: https://www.alltrac.net/tuning/fuelfaq.html
 

Selsvik

New member
Ok, so i disabled the Fuel Cut entirely by plugging both ends on the pressure sensor.
I have a boost gauge and an air fuel ratio gauge for safety, so i dont blow my engine.
But there is still something with the car... It doesn't like boost over ca 0,7bar(running on 1bar boost)
I dont know exactly what it is, but feels like it cuts the fuel or something.
The AFR gauge says 8,xx to 9,xx when i give full gas on third and fourth gear, so it runs very thick... And when it idle, it runs on ca 15,xx 16,xx.
Can this be what causing the troubles im having?
And btw, when i disconnect the battery for a little while, there is no problem with running 1bar boost...
Could it be something with the ecu not liking this?

Specs:
3" downpipe De-cat from gt4-play. Rest of the exhaust is original
Turbosmart boost controller - 1 Bar boost
Turbosmart boost gauge
AEM air fuel ratio gauge
POD Filter
 

underscore

Well-known member
Sounds like you're overfueling under boost and a little lean at idle. Do you have any intake or exhaust leaks?
 

Selsvik

New member
Not that i know of... Will check later! Where on the intake would this be a problem? Before or after the turbo? Because the hose before the turbo has a crack in it.
And i think i got the exhaust tight when i changed the downpipe, or else i would have heard it. The lambda sensor has been changed as well, so that should be ok.
 

underscore

Well-known member
Selsvik":sa9ct82r said:
Not that i know of... Will check later! Where on the intake would this be a problem? Before or after the turbo? Because the hose before the turbo has a crack in it.
And i think i got the exhaust tight when i changed the downpipe, or else i would have heard it. The lambda sensor has been changed as well, so that should be ok.

Everything after the AFM needs to be sealed (and really everything after the air filter so you're not sucking dirt and debris into the engine) or you'll have issues like this.
 

Selsvik

New member
I found out that there was a hose that had came off. So now that i attached it, it runs perfect on idle. (ca14,7AFR)
But it still dont like boost over 0,7 / 16 in AFR
 

underscore

Well-known member
Reset the ECU (pull the EFI fuse or disconnect the battery for a couple minutes) and see how it does, it'll probably have to relearn now that things are correct.
 
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