Overrun fuel cut too aggressive?. - 3000GT/Stealth International Message Center

keithmac · 02-12-2008, 03:00 PM

Anyone else find the overrun fuel cut too aggressive on these cars?, I`m thinking off adding a delay between when I shut the throttle and when the ecu sees the idle switch (maybe 3 seconds?) just to soften the transition between throttle and engine breaking a bit.

I was also thinking of dissabling the idle switch for 1/4 mile running, I don`t powershift and I`m sure the car cuts fuel between gearchanges making them harsher, longer to come back on the power.

Are the only factors for overun fuel cut idle switch on and revs over 1500 rpm or does the TPS come into play as well?.

TurboBob · 02-12-2008, 09:43 PM

Quote:

Originally Posted by keithmac

Anyone else find the overrun fuel cut too aggressive on these cars?, I`m thinking off adding a delay between when I shut the throttle and when the ecu sees the idle switch (maybe 3 seconds?) just to soften the transition between throttle and engine breaking a bit.

I was also thinking of dissabling the idle switch for 1/4 mile running, I don`t powershift and I`m sure the car cuts fuel between gearchanges making them harsher, longer to come back on the power.

Are the only factors for overun fuel cut idle switch on and revs over 1500 rpm or does the TPS come into play as well?.

check your dashpot.

keithmac · 02-13-2008, 03:44 PM

I did the check via the manual (dashpot contacts throttle lever at 2200 rpm) my car nevet stalls out, seems to rest at 1000rpm and then drop to 700.

I set the idle switch as per the manual as well with the feeler gauges, might have a play around with both to find a good compramise.

I take it with a propperly set up working dashpot it gradually falls to idle from 2000 rpm then?.

Cheers for the pointer.

TurboBob · 02-13-2008, 11:05 PM

it sounds like your dashpot is working, that pause at 1000 sounds about right.

Highboosted · 02-13-2008, 11:30 PM

Mine seems to act the exact opposite. It doesn't want to go into fuel cut/decel mode. just one of them things....

TurboBob · 02-14-2008, 01:02 PM

Quote:

Originally Posted by Highboosted

Mine seems to act the exact opposite. It doesn't want to go into fuel cut/decel mode. just one of them things....

the software I am working on right now lets to trigger the fuel cut on decel more easily. I just need to tweak on it some more and then I can post it.

Bob

keithmac · 02-14-2008, 04:46 PM

Had a play with today and tested on the way to work, with it all set up stock (idle switch and dashpot) it was awful to drive, took far to long to engine break (throttle plate was been opened too long, not a fuel cut issue).

I wound the dashpot rod in 10mm from the first setup and set the Idle Switch to come in at the last possible point (not using the feeler gauge method), it takes 5 seconds from foot off at WOT to the idle switch activating, I thoink this will be near where I want it to be, or maybe another 5mm to 10mm wound off the dashpot rod will be needed.

Just goes to show you can`t always trust the manual to get the best setup everytime!.

TurboBob · 02-14-2008, 05:37 PM

the dashpot does 2 things

helps eliminate stalling, and softens the bump if you step off the throttle without pushing in the clutch.

let us know how it goes. I'll measure mine tomorrow.

zalnn · 04-10-2008, 08:07 PM

Any updates?

I have an 3000GT SL (not sure if its supposed to have a dashpot or if it was removed), and would really like to soften the fuel cut (rapid RPM drop) when stepping off the throttle.

02-12-2008, 03:00 PM	#1 (permalink)
keithmac Forum Member Join Date: Sep 2006 Location: YORK / UK Trader Rating: (2)	Overrun fuel cut too aggressive?. Anyone else find the overrun fuel cut too aggressive on these cars?, I`m thinking off adding a delay between when I shut the throttle and when the ecu sees the idle switch (maybe 3 seconds?) just to soften the transition between throttle and engine breaking a bit. I was also thinking of dissabling the idle switch for 1/4 mile running, I don`t powershift and I`m sure the car cuts fuel between gearchanges making them harsher, longer to come back on the power. Are the only factors for overun fuel cut idle switch on and revs over 1500 rpm or does the TPS come into play as well?. __________________ JDM GTO TT, Emanage Blue - 450`s Hotwired Walbro - K&N - Blitz SSBC Port Methanol Injection - E85 - 12.4@115

02-13-2008, 03:44 PM	#3 (permalink)
keithmac Forum Member Join Date: Sep 2006 Location: YORK / UK Trader Rating: (2)	Re: Overrun fuel cut too aggressive?. I did the check via the manual (dashpot contacts throttle lever at 2200 rpm) my car nevet stalls out, seems to rest at 1000rpm and then drop to 700. I set the idle switch as per the manual as well with the feeler gauges, might have a play around with both to find a good compramise. I take it with a propperly set up working dashpot it gradually falls to idle from 2000 rpm then?. Cheers for the pointer.

02-13-2008, 11:05 PM	#4 (permalink)
TurboBob Resident mad scientist Join Date: Jan 2003 Location: Near Detroit Drives: 86 GN 91 RT/TT Trader Rating: (17)	Re: Overrun fuel cut too aggressive?. it sounds like your dashpot is working, that pause at 1000 sounds about right.

02-13-2008, 11:30 PM	#5 (permalink)
Highboosted king of ghetto Join Date: May 2004 Location: St. Louis Drives: '94 Stealth Turbo Trader Rating: (29)	Re: Overrun fuel cut too aggressive?. Mine seems to act the exact opposite. It doesn't want to go into fuel cut/decel mode. just one of them things.... __________________ pıdnʇs 'ɹǝʌo ǝɯ dılɟ Official member of the "I upgraded everything in my car and now it's slower than stock" club.

02-14-2008, 04:46 PM	#7 (permalink)
keithmac Forum Member Join Date: Sep 2006 Location: YORK / UK Trader Rating: (2)	Re: Overrun fuel cut too aggressive?. Had a play with today and tested on the way to work, with it all set up stock (idle switch and dashpot) it was awful to drive, took far to long to engine break (throttle plate was been opened too long, not a fuel cut issue). I wound the dashpot rod in 10mm from the first setup and set the Idle Switch to come in at the last possible point (not using the feeler gauge method), it takes 5 seconds from foot off at WOT to the idle switch activating, I thoink this will be near where I want it to be, or maybe another 5mm to 10mm wound off the dashpot rod will be needed. Just goes to show you can`t always trust the manual to get the best setup everytime!.

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02-14-2008, 05:37 PM	#8 (permalink)
TurboBob Resident mad scientist Join Date: Jan 2003 Location: Near Detroit Drives: 86 GN 91 RT/TT Trader Rating: (17)	Re: Overrun fuel cut too aggressive?. the dashpot does 2 things helps eliminate stalling, and softens the bump if you step off the throttle without pushing in the clutch. let us know how it goes. I'll measure mine tomorrow.

04-10-2008, 08:07 PM	#9 (permalink)
zalnn Forum Member Join Date: Oct 2005 Location: St Louis Trader Rating: (5)	Re: Overrun fuel cut too aggressive?. Any updates? I have an 3000GT SL (not sure if its supposed to have a dashpot or if it was removed), and would really like to soften the fuel cut (rapid RPM drop) when stepping off the throttle.