VEMS overrun fuel cut

[Jamo]

What rpm settings are you guys using for fuel cut?

I've raised mine to over 2000 rpm and it seems to be a lot better

[dkw_dude]

I'm running 1800 and "catching up" at 1400, works good for me
Btw I converted to VEMS, thanks to PNanassy for VEMS delivery and excellent support

[KRIENG]

What is VEMS overrun fuel cut
design for save engine or save fuel or return to idel

When I run over 3000 RPM and quick break engine stall

Thank you all
I found some information in

http://www.vemssupport.com/forum/ind...8&topic=1805.0

[A80Avant]

if the car is stalling then you need to put fuel cut kpa to : ZERO

fuel resume should not be more than 100rpm different, so if you have cut at 1500 , then resume should be at 1400

TPS: always 0. Because on some odd occasions when you very slightly press the pedal and its below 2% on low city driving, you will get no fuel and the car will jump around.

my settings are: kpa: zero
fuel cut 1400, resume 1300
TPS: Zero

[Jamo]

TPS = 0 If you do that over run is never enabled as TPS has to be below that value to enable!

[A80Avant]

Nope.
That means that tps needs to be equal to zero to enable the overrun fuel cut, in other words you are not pressing the accel. Pedal at all to enable. That's when you want the fuel cut to act anyway. When you are not doing anything with the tps. I get a fuel cut as normal that way.

sent using Android

[Jamo]

Except TPS is not always 0 when off the throttle.

i've seen on cars that tps can be 1% when off the pedal especially with the throttle damper hence the 2% value

[A80Avant]

That's why you calibrate the TPS!
If you calibrate it properly you get it zero! If you cannot calibrate it then you need to make the adjustments

sent using Android

[Jamo]

Actually I realised I never updated this thread from my original request
My settings after many experimentations were
Fuelcut = 1700
Resume = 1200
0 Kpa
2% Idle

[A80Avant]

whenever i used to leave a big difference between fuel cut and resume it makes the car hiccup on slow city driving as the revs round down to idle. As it goes between 1700 and 1200, there is a net of 500rpm that no fuel is happening, and that is also a recipe for stalling, as lamda is not always quick to bring values up to speed from 20.9 lamda to 1 which is at idle.

After practice and discussions with mattias, i ended up with the above setup and it has never stalled since.

Also if you use fuel cut below KPA as well (instead of zero) it can stall sometimes, exactly because the engine has to have some time to go from no fuel to lamda=1 in a very short period of time.

[KRIENG]

Test and find some information

Pic1
I set fuelcut below = 0 kpa and TPS = 2% test run found Pulse Width = 0
so fuel cut function depend on TPS
Pic2
I found fuel resume by IAC ON

Better result stalling seem away but sometime RPM drop to 500

May be code for fuelcut is

if( RPM > overrun_fuelcut && (TPS < iac_tps_threshold)) ||
( kpa < fuelcut_min_kpa){
then cut fuel;
}

http://www.vems.hu/wiki/index.php?pa...2FPowerRelated

[Jamo]

I've never stalled or had issues, those settings I've been running since about 2 months after the original post

[Billman]

I've never stalled or had issues, those settings I've been running since about 2 months after the original post

after 4 years with VEMS never had issues with this. If your RPMs drop that low then you have Idle setting issues.

[A80Avant]

Pic1
I set fuelcut below = 0 kpa and TPS = 2% test run found Pulse Width = 0
so fuel cut function depend on TPS
Pic2
I found fuel resume by IAC ON

Better result stalling seem away but sometime RPM drop to 500

May be code for fuelcut is

if( RPM > overrun_fuelcut && (TPS < iac_tps_threshold)) ||
( kpa < fuelcut_min_kpa){
then cut fuel;
}

http://www.vems.hu/wiki/index.php?pa...2FPowerRelated

If you read my post again you will understand that feature better. The leaner it is close to the idle rpm, the more the revs will drop and go towards stalling.

sent using Android

[KRIENG]

Thank you all.

whenever i used to leave a big difference between fuel cut and resume it makes the car hiccup on slow city driving as the revs round down to idle. As it goes between 1700 and 1200, there is a net of 500rpm that no fuel is happening, and that is also a recipe for stalling, as lamda is not always quick to bring values up to speed from 20.9 lamda to 1 which is at idle.

After practice and discussions with mattias, i ended up with the above setup and it has never stalled since.

Also if you use fuel cut below KPA as well (instead of zero) it can stall sometimes, exactly because the engine has to have some time to go from no fuel to lamda=1 in a very short period of time.

if the car is stalling then you need to put fuel cut kpa to : ZERO

fuel resume should not be more than 100rpm different, so if you have cut at 1500 , then resume should be at 1400

TPS: always 0. Because on some odd occasions when you very slightly press the pedal and its below 2% on low city driving, you will get no fuel and the car will jump around.

my settings are: kpa: zero
fuel cut 1400, resume 1300
TPS: Zero

Thank you all ,I try to find best solution

In Pic1 I set fuelcut above 1500 and it cut at 1784
however if I set fuel cut 1400, resume 1300 It may be cut more than 100 RPM

Maybe fuelcut RPM 1400 means if you drive lower than 1400 this funcion not active
when you drive morethan 1400 and decelate it will active

I must fixed idel too.

I found
http://www.msextra.com/doc/ms1extra/...Manual.htm#wtf
"I would suggest it was around 800rpm higher than the tickover RPM " (tickover = idel)

Forgive me,My english is very poor