Welcome to the SR20 Community Forum - The Dash.
Register
SR20 forum logo

Thread: Soften deceleration fuel cut on low RPMs

+ Reply To Thread
Posts: 11-20 of 44
2013-07-23 18:58:37
#11
Originally Posted by Nicoxis
Originally Posted by Haulin200sx
Originally Posted by Nicoxis
Originally Posted by OnTheChip
Yes, The "FC" tables are for overrun fuel cut.


This is what I currently have, so how do I modify it to smooth things out?


Not sure if this will work on not but try using the same rpm from the top to the bottom (use the higher rpm value from the coldest temp) then repeat for all tables. Give it a try. Can't hurt, if it doesnt work just put it back to what was preloaded.


I thought the same and had already tried that, but the engine kept shutting itself off :/ Thanks for the suggestion though


What exactly happens? did it stall at 3,000rpm?

I also have the herky jerky ride if i go slow in first with my foot just a bit on the gas pedal. I always thought this was due to aggressive timing off idle. I lowered mine more like the stock timing table around that area just off idle and it didnt make much of a difference
2013-07-23 19:14:01
#12
Originally Posted by Haulin200sx


What exactly happens? did it stall at 3,000rpm?



It wouldn't even idle, it would shut unless I kept pulsing the gas pedal.

I'll keep testing...
2013-07-23 19:47:09
#13
did you try this on just the first table or all of them. Make sure the OFF tables are lower like Dave said also

Did you try 3,000RPM in the first table, 2,900RPM in the second through the whole coolant temp range...etc... etc...
2013-07-23 20:08:55
#14
I did 2900, 2800, 2850 on the first three tables from 0° to 110°
2013-07-23 23:38:16
#15
If your going to make changes, it should probably be done to ALL OF THEM. lets go over this again.

table 1: make the entire table 3000
table 2: " " " " 2900
table 3: " " " " 2950
table 4: " " " " 2850
table 5: make the entire table 2750
table 6: make the entire table 2800

Does you car do the herky gerky when its cold? I don't think mine does. Anyways I still can't grasp all this fuel overrun cut stuff...let alone why there are 6 tables which appear to all work differently.
2013-07-24 00:32:55
#16
Originally Posted by Haulin200sx
If your going to make changes, it should probably be done to ALL OF THEM. lets go over this again.

table 1: make the entire table 3000
table 2: " " " " 2900
table 3: " " " " 2950
table 4: " " " " 2850
table 5: make the entire table 2750
table 6: make the entire table 2800

Does you car do the herky gerky when its cold? I don't think mine does. Anyways I still can't grasp all this fuel overrun cut stuff...let alone why there are 6 tables which appear to all work differently.


OK, I'll try it that way.

When cold there's almost no jerkiness and I also can't grasp all this overrun stuff, well it's been just a couple of months since I got my nismo RT so I think its acceptable lol hahahha
2013-07-24 08:36:20
#17
Fuel Cut tables have always baffled me, the description in help says a lot of stuff, but not what changing things higher or lower rpm, and/or making the rpm values closer or further apart will change the driving experiance.

I recently picked up a GTIR Pulsar, with totally stock ecu, and its a joy to drive compare to my P10, it starts and idles perfectly, can be driven at light load low speed easily, has rock steady idle all the time. My P10 is a pig in traffic, and idles horribly at times. Yeah the P10 with the tuned ecu is faster and fine under load, the the light load and idle stuff is baffling and so hard to work out what and where needs to be adjusted to sort these issues out.
2013-07-24 19:52:31
#18
Originally Posted by Evlnxr
Fuel Cut tables have always baffled me, the description in help says a lot of stuff, but not what changing things higher or lower rpm, and/or making the rpm values closer or further apart will change the driving experiance.

I recently picked up a GTIR Pulsar, with totally stock ecu, and its a joy to drive compare to my P10, it starts and idles perfectly, can be driven at light load low speed easily, has rock steady idle all the time. My P10 is a pig in traffic, and idles horribly at times. Yeah the P10 with the tuned ecu is faster and fine under load, the the light load and idle stuff is baffling and so hard to work out what and where needs to be adjusted to sort these issues out.


^^^THIS!
2013-07-24 20:08:15
#19
NismoTronicSA Help - ACCEL/DECEL Tab
2013-07-24 20:24:21
#20
Originally Posted by Evlnxr
Fuel Cut tables have always baffled me, the description in help says a lot of stuff, but not what changing things higher or lower rpm, and/or making the rpm values closer or further apart will change the driving experiance.

I recently picked up a GTIR Pulsar, with totally stock ecu, and its a joy to drive compare to my P10, it starts and idles perfectly, can be driven at light load low speed easily, has rock steady idle all the time. My P10 is a pig in traffic, and idles horribly at times. Yeah the P10 with the tuned ecu is faster and fine under load, the the light load and idle stuff is baffling and so hard to work out what and where needs to be adjusted to sort these issues out.


I think that you will find that the majority of the idle problems that customers have are tied to mechanical issues.

The idle and light load is ALWAYS the hardest part of the tune to dial in and get just right, but anything like a MAF leak or vac leak at the IM will cause all kinds of problems.

To the OP, if you car is literally stalling after over run fuel cut .. it is HIGHLY likely that you idle air valve is not opened far enough to catch the idle OR that section of the fuel/ignition map needs some adjustment.

A lot of people also make the mistake of thinking that they can idle larger injectors (earlier style) at the same AFR as smaller stock injectors. This can definitely cause an erratic idle, try adding a little fuel to the idle portion of the map or even adjusting your battery offset tables.

I do understand that the idle and fuel cut parameters can be a little overwhelming when you first look at them.

But if you take the time and really read how it all works together and adjust 1 thing at a time to see a trial and error you might get the hang of things.

Also, if you guys have some more specific questions, other than this stuff baffling .. we can give you a more specific answer on what to change!
+ Reply To Thread
  • [Type to search users.]
  • Quick Reply
    Thread Information
    There are currently ? users browsing this thread. (? members & ? guests)
    StubUserName

    Back to top