The Top DSM Community on the Web

For 1990-1999 Mitsubishi Eclipse, Eagle Talon, Plymouth Laser, and Galant VR-4 Owners. Log in to remove most ads.

Please Support ExtremePSI
Please Support ExtremePSI

ECMlink LearndIdleAdj and ISC position with larger cams auto automatic trans

This site may earn a commission from merchant
affiliate links, including eBay, Amazon, and others.

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Brandon Nicholson

Proven Member
75
70
Jun 23, 2014
Scottsdale, Arizona
Hello there! so I've just got my car running with a refreshed cylinder head and larger cams- (BC280s,Kiggly steel street beehives and AEM cam gears) and I've got my idle stabilized at 1100 rpms or so and my process went like this.. Got the car idling and up to temp, then set ignition timing with the light(made sure to grounds the connector) then worked on getting ISC and LearndIdleAdj to 35 and 135, that all went smoothly and idle is consistent and will return with no issues, what I have questions/concerns on is when I put the car in D or R (since it's auto) the ISC shoots up to compensate for the load on the engine which goes to 90-100 steps, this seems to function correctly but the issue I'm facing is that learned idle will now slowly start climbing back up since ISC is much higher. What this is in turn doing is making the car surge for a second or two when putting it back in park or neutral.. Is there something I can do to where the isc retains functional but when in drive learned idle isnt cranking up making the car surge in park?
 

Attachments

  • ISC and LrndIdleAdj.elg
    107.4 KB · Views: 24
I think your issue is more likely the lack of "Coasting FC offset". Your idle is pretty darn high and could use a 2 to 300 Coasting offset value so that the ecu doesn't inject fuel and cause the car to surge. Maybe even consider lowering your idle to 1000 as those cams aren't terribly aggressive and may not require such a high idle anyways.

As far as the isc goes, a high value doesn't indicate bad behavior but one of a range of values (0-120) that the isc motor uses to control the idle. 30 is recommended as the gold standard at ide because that's generally the sweet spot where the isc can best control rpms in either direction. A low isc value indicates the ecu is trying lower the idle. A higher value indicates the ecu is wanting more air through the isc and thus a higher idle.

I've never owned an auto so maybe there's something I don't understand though.
 
Last edited:
I think your issue is more likely the lack of "Coasting FC offset". Your idle is pretty darn high and could use a 2 to 300 Coasting offset value so that the ecu doesn't inject fuel and cause the car to surge. Maybe even consider lowering your idle to 1000 as those cams aren't terribly aggressive and may not require such a high idle anyways.

As far as the isc goes, a high value doesn't indicate bad behavior but one of a range of values (0-120) that the isc motor uses to control the idle. 30 is recommended as the gold standard at ide because that's generally the sweet spot where the isc can best control rpms in either direction. A low isc value indicates the ecu is trying lower the idle. A higher value indicates the ecu is wanting more air through the isc and thus a higher idle.

I've never owned an auto so maybe there's something I don't understand though.
Thank you for the information Vegas! What I’ll go ahead and try doing is setting my idle lower as-well as adjusting my FC offset to a more reasonable value. My initial reason for setting my idle near 1100 was for giving me a little bit more vacuum at idle, around 11-12 inhg. And I have ignition timing at idle around 20deg to increase idle tq. Would this cause me surging issues also?
 
And I have ignition timing at idle around 20deg to increase idle tq. Would this cause me surging issues also?
Don't quote me but I do believe increased ignition timing can lead to surge although I forget the mechanism. The rule of thumb for coasting fc offset is your idle minus 200. So, 1100-900 would be an offset value of 200. You can increase or decrease that to your desire.
 
Don't quote me but I do believe increased ignition timing can lead to surge although I forget the mechanism. The rule of thumb for coasting fc offset is your idle minus 200. So, 1100-900 would be an offset value of 200. You can increase or decrease that to your desire.
I’ll try a few things out and report back, thank you!
 
@Vegas Smith so I went ahead and made some changes like you mentioned and put in a stock 2g timing map to get rid of any variables, set my idle to 1000 and its hovering around 950 +-100, still though same surge due to learned idle going up in drive making it surge in park.. Here's a new log and some screenshots
You must be logged in to view this image or video.
You must be logged in to view this image or video.
 

Attachments

  • 1000rpm idle, FC offset change, stock 2g timing tables.elg
    316.5 KB · Views: 30
First, I'll say that I've never owned an auto so I don't know if there is something unique about how the autos idle etc. I'd hate to give you bad information. Just a disclaimer.
Second, anytime I change an Idle setting I reset the isc prior to altering the biss screw. If you don't reset the isc, which resets learnedidleadj, then you can adjust your idle to the perfect spot but the learnedidleadj will basically keep learning and fighting you if that makes sense. Here's how to reset the isc: https://www.sixsigmatuning.com/dsm-idle-control
 
Might want to reset all fuel trims also. Start fresh. Maybe put the 2g fuel map in also or at least compare it to yours.
My auto car doesn't surge when I go from drive to park, it will idle up a bit and then settle back to the normal idle so being an auto shouldn't make any difference in it but I haven't looked at the tune or log. Just my .02¢
 
Might want to reset all fuel trims also. Start fresh. Maybe put the 2g fuel map in also or at least compare it to yours.
My auto car doesn't surge when I go from drive to park, it will idle up a bit and then settle back to the normal idle so being an auto shouldn't make any difference in it but I haven't looked at the tune or log. Just my .02¢
I went ahead and tried a stock SD table but that didn’t really make much difference either. It’s just that when it’s in drive the isc is compensating and trying to hit a target idle of 900 in drive. That in turn cranks up learned idle adj because the car isn’t moving and still thinks it’s idling, which it is but skews my data. everything is working correctly in this sense but the idle is still being “learned” in drive causing these learned values to change.. I think it’s doing this because of the larger cams. It has like 3inhg in drive with these cams and I believe that in turn is driving up isc when it’s in drive. This is what it’s currently doing I made a video this time.
 
First, I'll say that I've never owned an auto so I don't know if there is something unique about how the autos idle etc. I'd hate to give you bad information. Just a disclaimer.
Second, anytime I change an Idle setting I reset the isc prior to altering the biss screw. If you don't reset the isc, which resets learnedidleadj, then you can adjust your idle to the perfect spot but the learnedidleadj will basically keep learning and fighting you if that makes sense. Here's how to reset the isc: https://www.sixsigmatuning.com/dsm-idle-control
That is where my issue is, The learned idle is fighting me whenever the car is in drive sitting at a stop. Neutral and park are wonderful since isc position and learned idle are in range of control, but the increased load sitting at a light makes the car all confused thinking that it’s current isc value is the one that needs to be learned. It’s almost like it should stop learning once the ecu knows it’s in drive so as to not skew it in other conditions, And if they are setup properly at idle in park it should still make isc corrections but not learn them once it it’s loaded up with the automatic. Is that feasible?
 
Idk if I do things differently (I'm absolutely positive I do) but I adjust my tune, in drive (deadtimes). I don't adhere to the normal "settings" on ISC and airflow per rev but I let the car talk to me and make adjustments accordingly to her liking. I admit I fiddle with her alot until I get there.
 
Idk if I do things differently (I'm absolutely positive I do) but I adjust my tune, in drive (deadtimes). I don't adhere to the normal "settings" on ISC and airflow per rev but I let the car talk to me and make adjustments accordingly to her liking. I admit I fiddle with her alot until I get there.
What ranges do you typically shoot for when your in drive? And are you making fine adjustments in injbatteryadj? I’m currently only making global adjustments. Right now in park at idle isc steps are between 25-31 but in drive goes to 100steps to make sure it doesn’t stall out.
 
Well, thats the deal. I don't have any ranges that I shoot for since the motor is pretty highly modified. I've built motors so long I just feel it out and make some injector voltage adjustments. Load her up hard electrically and play with that and then gradually unload her to "play". Usually I find a good 9 volt point (which will barely run the car if it would fire the injectors) then make a nice long "swoop" on the graph down to zero at 16 volts. My cars start up in winter with no FIAV's just the right sd tune. Like I said, I do play with it a lot but they like fine touches. Sometimes negative dt is involved. Just some little things but its nice when you get dialed in. I could throw up a tune to have criticized but my tune issues are usually with WOT fine tunes. I am no pro that is for sure. I do fine tune the idle at +/-5% STFT AND LTFTs. If they are that close, and the car likes it, its good enough for me.
 
Support Vendors who Support the DSM Community
Boosted Fabrication ECM Tuning ExtremePSI Fuel Injector Clinic Innovation Products Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications MyMitsubishiStore.com RixRacing RockAuto RTM Racing STM Tuned

Latest posts

Build Thread Updates

Vendor Updates

Latest Classifieds

Back
Top