Fuel cut

Q&A regarding engines, turbos, and intercoolers and power upgrades

Fuel cut

Postby Rpz123isme » Thu Oct 18, 2012 12:27 am

Ok guys I cut my pim wire to the ecu in hopes to delete my fuel cut from the car. but sadly Instead of 11psi fuel cut I now have a 16psi fuel cut. any tips in completely removing the fuel cut? I know some people say its not safe for the motor, but I am not concerned about that. I can build another one for pennies on the dollar if something goes wrong. the car is an 88 165 with a manufacture date of nov 1987.

Thanks
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Re: Fuel cut

Postby jaydog82 » Thu Oct 18, 2012 1:00 am

Just remove the vac line to the boost sensor and cap off or change the vac tee out so there's no leaks
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Re: Fuel cut

Postby Rpz123isme » Thu Oct 18, 2012 1:13 am

But if I already disabled the signal from the sensor how will that change anything? Ill try it never the less
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Re: Fuel cut

Postby l0ch0w » Thu Oct 18, 2012 1:21 am

on a gen 2 eventually the motor hits fuel cut because the MAF sensor pegs out.

Only way around this would be to switch to a gen 3 EFI.
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Re: Fuel cut

Postby Rpz123isme » Thu Oct 18, 2012 1:37 am

I have a gen 1 motor and ecu. if its the mass I can rig it to never hit 100%max. but seeing how my old 185 never ran into this problem at 18psi im a little lost.
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Re: Fuel cut

Postby Rpz123isme » Thu Oct 18, 2012 1:44 am

found this.

erolit wrote:TPS = Turbo pressure sensor. on the st185 it provides a pressure signal to the ECU from which the ECU calculates fuel cut. It also has a separate wire connecting it to the stock boost gauge on the dash board.

Appart from these 2 functions it serves no other purpose. There is no pressure sensor based fuel/ignition corrections on an st185 ECU.

If you electronically disconnect it from your engine (ie you cut the PIM wire, unplug the sensor wiring harness etc.) the ecu will begin to calculate fuel cut based on the signal from your AFM & throttle position, and when you hit airflow based fuel cut you have to reset your ECU (by pulling a battery terminal). Basically dont do it.

It will also (by some means which i have yet to establish) pull ignition timing much more readily with the sensor electronically disconnected.

If you want to kill fuel cut, the best way to do is is to unplug the vacuum line from the TPS, and leave everything as it is. This is 100% effective with zero side effects (except for complete absence of pressure related fuel cut)

Elliott



makes since now. so when the ecu does not see any signal it uses a back up the afm. so leave the electronics alone.
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Re: Fuel cut

Postby Rpz123isme » Thu Oct 18, 2012 2:10 am

Works great! now my 3 mode home made boost controller can be used!

mode one stock boost

mode two 11psi

mode three 17psi


hopefully soon I can hit the dyno
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Re: Fuel cut

Postby jaydog82 » Thu Oct 18, 2012 2:44 am

I told you it will work, iv been running 15psi like this for months.
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Re: Fuel cut

Postby Rpz123isme » Thu Oct 18, 2012 3:01 am

Thanks. I just didnt know when u cut the pim wire the fuel cut is now on the afm.
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Re: Fuel cut

Postby celicast184 » Sat Nov 24, 2012 7:33 am

what we always do is plug the turbo pressure sensor with a plastic bb (airsoft bb) into the vac line before the sensor. this way, ecu still sees the signal but allows boost to be raised.
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