About to throw in the towel nailing down idle

[GHuggins]

Sorry to hear about the pump. Also not sure why the histograms aren't working unless some of the pids weren't compatible with the vehicle in question.

BUT it's no longer surging? Just stalling now? Did you get your MAF dialed back in? What are your fuel trims? Sorry don't have my labtop with me to look at your datalog or tune again. Speaking of which, do you have a latest tune and log to post?

Since it's no longer surging, try adding back (.5 to 1g/s) at a time to your entire min airflow table and see if the stall goes away. Just don't go beyond what it takes to get your problem fixed.

[pganci]

GHuggins, I was just staring at my tune and in looking the Injector Control Offset the Offset Select is set to Vacuum, if I am running a boost referenced FPR shouldn't that be set to MAP? And should the Offset Vs Volts Vs MAP table be set to something, it is currently zero'd out? Lastly the offset table that I originally copied from the Injector Dynamic spreadsheet was off slightly, would this small amount have any effect, see attachment.

Offset.JPG

Thanks

Paul

[schpenxel]

GHuggins, I was just staring at my tune and in looking the Injector Control Offset the Offset Select is set to Vacuum, if I am running a boost referenced FPR shouldn't that be set to MAP? And should the Offset Vs Volts Vs MAP table be set to something, it is currently zero'd out? Lastly the offset table that I originally copied from the Injector Dynamic spreadsheet was off slightly, would this small amount have any effect, see attachment.

Offset.JPG

Thanks

Paul

You'll either use the offset vs. volts vs MAP or offset vs. volts vs VAC, you will NOT use both. It's two different ways of doing the same thing basically.. so don't worry about it

[pganci]

I am back up and running and playing with the suggestions I was given which helped with the surging when cold. What's happening now is from an initial start and going into gear it will pull away smooth but as soon as I let off the throttle and come to a stop it will start sputtering and popping until I give it enough throttle to push through it. Once I have been driving for like 10 minutes it does not seem to do it, what I see when this is happening is my timing is jumping all over the place going negative from what I believe is the >Spark Limiter >Minimum Timing Table, the tuner had set this table to 12 degrees to keep it from dipping but then it would dip to 12 and stay there for a few seconds and the vehicle would stumble.

Something I notice when I am looking at the main spark timing advance when scanning is when I am in idling in park my cylinder air mass bounces between .32 an .36 g/cyl and when I put it in gear it jumps to .44 and .48 g/cyl, isn't that high for idling?

Here is the tune I am currently working with, I have tired so many different settings I have lost track of what I changed.

Looking for input to fix this pig or put her out of my misery!

Paul


Ganci E38 T42 Dyno 3.00 Pulley Beta 05.08.2015.1 Modified.hpt

[schpenxel]

Got a log to go along with it?

Mine idles at about .17 g/cyl. just as a rough reference point.. Stock LS2 engine. Obviously yours is a totally different setup so I'm not sure how much good that number will do you.

What's your timing at at idle once everything is stable?

[pganci]

Got a log to go along with it?

Mine idles at about .17 g/cyl. just as a rough reference point.. Stock LS2 engine. Obviously yours is a totally different setup so I'm not sure how much good that number will do you.

What's your timing at at idle once everything is stable?

Here is a short log from yesterday, I made a few changes but it should be pretty much the same. I notice that when the timing is swinging in a rhythm its seems fine its when its choppy or holding still that it sputters.

Thank you for taking a look.

[rio95]

***Updated for clarity and added CFCO recommendation 7/18/12***

I just did this again and refined the process a little. As of 3/23/11 this is now updated for 2.23 and the config/histo changed to plot dynamic airflow. I have only ever done it on a manual car so the auto steps are SWAG's.

- Set you're target idle speed to whatever you would like it to be (be reasonable based on your cam)

- Set your idle speed minimum to the same as your lowest target idle speed. IE: I have 900 when cold ramping down to 750 when warm so I'd use 750 for idle speed minimum.

- Make your idle spark table match the corresponding columns from your HO spark table. The reason for this is that the idle spark table is only referenced when the speed is 0 and the HO table is referenced when moving. I can't see a reason for wanting them to be different. If you make changes to one, make them to the other as well. You do want the advance in the idle cells to not be optimum. I suggest ~15-20 degrees. This is so the adaptive idle spark can add spark and actually have it do something. If you have your idle spark at the ideal then adding to it won't help.

- Under Idle, Idle Airflow, Base Running Airflow, zero out the entire Airflow Final Minimum table. This prevents the PCM from predicting any minimum airflow which would prevent us from finding the real minimums.

- I suggest leaving the idle adaptive spark control overspeed and underspeed tables and adaptive idle proportional and integral tables as they come stock. Since I can't find an empirical way to determine how much to edit these tables, i leave them alone and they seem to do a nice job even when I had my lopey big overlap cam. The other thing I'll say about these is the airflow tables under proportional and integral should remain stock, even on a scaled tune. I've tried cutting them in half along with all the other airflow/airmass related tables when I do a 50% scaled tune and it doesn't work out well.

- Unlike gen 3 idle tuning, start with a warmed up engine. AC off. This is where idle airflow will be the smallest. While parked, start the motor and in VCM controls command the different RPM's in the airflow final minimum table; 650, 800, 1000, 1200, etc. As of 2.23 you cannot type in numbers into this field anymore. I think it stops at 1200 now. Leave it at each cell for at least 30 seconds, 60 is better so the values in each cell can stabilize. You may have a hard time staying in the 650 RPM cell until later when the numbers get more accurate or if you have a big cam you may not be able to get it to go that low at all. Automatic guys will want to do this in park and again in drive with the e-brake on and tire stops for safety. Use the park numbers for park and neutral and the drive numbers for all other gears, although in actuality you will probably only be able to get the 660 and 800 numbers while in drive. Manual guys use the neutral numbers for all gears.

- Using histogram 10 on average (A), which plots dynamic airflow against the final idle airflow minimum table. The idea is to command the lowest RPM in each field so we find the minimum flow for each cell. Simply using the "L" function (lowest value) of the histogram doesn't yield good results.

- Paste the numbers you get directly into the Airflow Final Minimum table for all gears (auto guys use the numbers for park and neutral and re-do in gear and paste those values in all other gears). Leave the values above the RPM's you stopped as zeros and make up some numbers for the 450 and 250 RPM cells that follow the trend of the line. Then sutract 20% from the whole table (select all and multiply by .8).

- Flash and restart the engine. Log idle adapt advance against the final idle airflow minimum table with histo 11 using the average (A). Command the RPM's again, just like before. Copy and paste these numbers (paste special, multiply by %) into the appropriate cells. (again, auto guys will need to do this in park and drive) Raise or lower the lower RPM cells accordingly to make a straight line. Lather, rinse, repeat until the adaptive spark numbers are +-1 degree. I realize we're taking the number of degrees that the adaptive idle control is having to add or remove and pasting that into the tune as a percentage of airflow and that doesnt make any sense, but it works. With each iteration you will see the adaptive idle spark getting closer to zero. The less the adaptive idle spark has to work the closer we are to the real idle airflow minimum. Even though the adaptive idle spark does not come into play when moving, since the airflow numbers are correct there should be no dipping, hanging or flaring when returning to idle.

Lastly for the manual guys, I recommend disabling CFCO. I was still having some flaring/dipping when I was in traffic at low RPMs and pushed the clutch in. Disabling CFCO cleared this right up.

thanks for this guide. I'm going to play around with this procedure on my car. When you talk about setting the RPM in the VCM scanner do you mean go to VCM controls to the special tab and plug in a desired RPM in the desired RPM box? I've never done this so I'm not sure if this is what you mean. Does this force the car to idle at that RPM?

Do you disable CFCO by maxing out the enable VSS speed box?

[rio95]

Also, how do you recommend finding to best idle timing? Do you log delivered engine torque while varying idle spark by say 4 deg at a time to find max torque and then remove 7-10 degrees from that value. Or do you log MAP to find what timing produces the best vacuum and then subtract 7-10 degrees? You figure out idle timing before doing anything with RAF, right? Should RAF table be zeroed out when doing one of the above methods I described?

[5_Liter_Eater]

Yes, through VCM controls. It forces the car to obtain that RPM.

I maxed out the enable ECT but either would work.

thanks for this guide. I'm going to play around with this procedure on my car. When you talk about setting the RPM in the VCM scanner do you mean go to VCM controls to the special tab and plug in a desired RPM in the desired RPM box? I've never done this so I'm not sure if this is what you mean. Does this force the car to idle at that RPM?

Do you disable CFCO by maxing out the enable VSS speed box?

[5_Liter_Eater]

Also, how do you recommend finding to best idle timing? Do you log delivered engine torque while varying idle spark by say 4 deg at a time to find max torque and then remove 7-10 degrees from that value. Or do you log MAP to find what timing produces the best vacuum and then subtract 7-10 degrees? You figure out idle timing before doing anything with RAF, right? Should RAF table be zeroed out when doing one of the above methods I described?

If I could play with the timinig in real time on my E40 I might mess with that but I haven't. The 15-20 degree's is just a recommendation.

[rio95]

If I could play with the timinig in real time on my E40 I might mess with that but I haven't. The 15-20 degree's is just a recommendation.

I did some idle timing testing and got the following results. Some things are what I expected, but some things I don't understand. Maybe someone can help me interpret. Vacuum increased with increased timing, which I expected. Delivered torque did the opposite, but from what I've read it's calculated and timing is one of the inputs, so those values and their relationship might be bogus. I also expected average adaptive idle to change as I changed idle timing, but it didn't (did have greater variation though to combat surging with higher timing).

The car surged more at idle as I added timing if adaptive idle was turned off. In fact, it surged so bad at the high timing that it would almost die. Idle was pretty steady even without adaptive idle at the lower timing. I also did not see the RPMs change a noticeable amount when I turned adaptive off, so maybe my airflow table accidently good.

After doing this is seems there may be no optimal spot, so I may just run like 16 deg, which I have been doing for a year. The things I'm trying to accomplish are increase idle vacuum (think low vacuum is affecting my braking at times), get rid of surge and occasional stalling when car is hot and AC is on, and RPM dip when I push in clutch when coming to a stop (doesn't seem to dip far all the time. Turning CFCO off might fix this I'm guessing).

[5_Liter_Eater]

Interesting. Obviously adding timing is going to increase efficiency and lower ETC and thus MAP which are both desireable. But if you're at peak efficiency then the adaptive idle advance can't react to increase RPM should it need to by increasing spark. I'd say all the other things you're trying to accomplish should be taken care of by getting the base running airflow calibrated in the upper (~2000 and below) RPM range.

[rio95]

Interesting. Obviously adding timing is going to increase efficiency and lower ETC and thus MAP which are both desireable. But if you're at peak efficiency then the adaptive idle advance can't react to increase RPM should it need to by increasing spark. I'd say all the other things you're trying to accomplish should be taken care of by getting the base running airflow calibrated in the upper (~2000 and below) RPM range.

I don't follow your last statement. Don't my idle advance averages make it seem like my airflow table is already good? I think this is further confirmed by the fact that my average idle values are pretty much the same between idle adapt off and on.

[5_Liter_Eater]

Well your numbers abve are at idle. You're having trouble coming back down to idle (dipping) which makes me think the 1000-2000 range needs a bump.

[rio95]

Well your numbers abve are at idle. You're having trouble coming back down to idle (dipping) which makes me think the 1000-2000 range needs a bump.

I will try adding some airflow like you suggested and see what happens. I may also try bumping my idle when AC is on. I'm really only getting the dipping/surging when the AC is on.

I studied the variation (standard deviation) of the data I collected the other day and you can see how the surging increased with timing. Although I got more vacuum with more timing, if it's going to create more surge, maybe adding timing isn't a good idea. Do you think adjusting airflow could counteract the surging? I'm not understanding the idle adapt either.... Seems to react different than how you described. I thought idle adapt average would change as I change the idle timing to maintain the same idle. Instead, the average idle adapt was pretty much zero in all cases and instead, the ETC decreased as timing increased to maintain target idle. I'm missing something here....

[5_Liter_Eater]

Are you collecting all this data while stopped? Because adaptive idle advance is only active when not moving. And did you do the procedure while hot with the AC on? Unlike the third gen idle procedure (cold, no AC) this one is supposed to be while warm and with the AC on. I'm not whats going on with the surging with lots more advance. I'd like to see a log of it with the idle config used. But I'm not sure how productive it is to debug that rather than just back it off a bit.

[rio95]

Are you collecting all this data while stopped? Because adaptive idle advance is only active when not moving. And did you do the procedure while hot with the AC on? Unlike the third gen idle procedure (cold, no AC) this one is supposed to be while warm and with the AC on. I'm not whats going on with the surging with lots more advance. I'd like to see a log of it with the idle config used. But I'm not sure how productive it is to debug that rather than just back it off a bit.

I agree this might not be too worthwhile, but I like to learn and understand what's going on.

This data is all from idle, hot, in neutral, with parking brake on. Unfortunately, I didn't have the AC on though... Missed that comment

Here are some tunes and scans:

stock timing.hptstock timing.hpladded 12deg.hptadded 12deg.hpl

[fuzzkill]

I must be missing a step here, but my #10 histogram average values are from ~10 to ~16 from the 600rpm to 1200rpm spread. The airflow table only allows a maximum value of 8.5lb/min, am I supposed to be modifying this number before it goes back into the airflow table? I see that it is supposed to be multiplied by .8 but even then the values I'm getting from the histogram are over the values allowed on the table.

Edit: Are the values in the histogram in g/sec and needs to be converted to lb/min? That seems to give a number close to what I was expecting ...

[5_Liter_Eater]

Yes, all the cool kids use g/sec. I'll go back and add the statement to make sure the units are the same.

[majorpayne317641]

***Updated for clarity and added CFCO recommendation 7/18/12***

I just did this again and refined the process a little. As of 3/23/11 this is now updated for 2.23 and the config/histo changed to plot dynamic airflow. I have only ever done it on a manual car so the auto steps are SWAG's.

- Set you're target idle speed to whatever you would like it to be (be reasonable based on your cam)

- Set your idle speed minimum to the same as your lowest target idle speed. IE: I have 900 when cold ramping down to 750 when warm so I'd use 750 for idle speed minimum.

- Make your idle spark table match the corresponding columns from your HO spark table. The reason for this is that the idle spark table is only referenced when the speed is 0 and the HO table is referenced when moving. I can't see a reason for wanting them to be different. If you make changes to one, make them to the other as well. You do want the advance in the idle cells to not be optimum. I suggest ~15-20 degrees. This is so the adaptive idle spark can add spark and actually have it do something. If you have your idle spark at the ideal then adding to it won't help.

- Under Idle, Idle Airflow, Base Running Airflow, zero out the entire Airflow Final Minimum table. This prevents the PCM from predicting any minimum airflow which would prevent us from finding the real minimums.

- I suggest leaving the idle adaptive spark control overspeed and underspeed tables and adaptive idle proportional and integral tables as they come stock. Since I can't find an empirical way to determine how much to edit these tables, i leave them alone and they seem to do a nice job even when I had my lopey big overlap cam. The other thing I'll say about these is the airflow tables under proportional and integral should remain stock, even on a scaled tune. I've tried cutting them in half along with all the other airflow/airmass related tables when I do a 50% scaled tune and it doesn't work out well.

- Unlike gen 3 idle tuning, start with a warmed up engine. AC on. This is where idle airflow will be the smallest. While parked, start the motor and in VCM controls command the different RPM's in the airflow final minimum table; 650, 800, 1000, 1200, etc. As of 2.23 you cannot type in numbers into this field anymore. It stops at 1200 now. Leave it at each cell for at least 30 seconds, 60 is better so the values in each cell can stabilize. You may have a hard time staying in the 650 RPM cell until later when the numbers get more accurate or if you have a big cam you may not be able to get it to go that low at all. Automatic guys will want to do this in park and again in drive with the e-brake on and tire stops for safety. Use the park numbers for park and neutral and the drive numbers for all other gears, although in actuality you will probably only be able to get the 660 and 800 numbers while in drive. Manual guys use the neutral numbers for all gears.

*Note that the histgrams are set up in g/sec, because thats what I like. The units in your tune for the final airflow min table may default to lb/min. Make sure they match before proceeding. Either change the histo to #/min or change the units in the tune to g/sec.*

- Using histogram 10 on average (A), which plots dynamic airflow against the final idle airflow minimum table. The idea earlier was to command the lowest RPM in each field so we find the minimum flow for each cell. Simply using the "-" function (lowest value) of the histogram doesn't yield good results. Copy the numbers you got in histo 10.

- Paste the numbers you get directly into the Airflow Final Minimum table for all gears (auto guys use the numbers for park and neutral and re-do in gear and paste those values in all other gears). Leave the values above the RPM's you stopped at as zeros and make up some numbers for the 450 and 250 RPM cells that follow the trend of the line. Then sutract 20% from the whole table (select all and multiply by .8). Don't ask, just do it.

- Flash and restart the engine. Use histo 11 to plot the idle adapt advance spark against the final idle airflow minimum table using the average (A). Command the RPM's again, just like before. Copy and paste these numbers (paste special, multiply by %) into the appropriate cells in the tune. (again, auto guys will need to do this in park and drive) Raise or lower the lower RPM cells that are toolow to idle in accordingly to make a straight line. Lather, rinse, repeat until the adaptive spark numbers are +-1 degree. I realize we're taking the number of degrees that the adaptive idle control is having to add or remove and pasting that into the tune as a percentage of airflow and that doesnt make any sense, but it works. With each iteration you will see the adaptive idle spark getting closer to zero. The less the adaptive idle spark has to work the closer we are to the real idle airflow minimum. Even though the adaptive idle spark does not come into play when moving, since the airflow numbers are correct there should be no dipping, hanging or flaring when returning to idle.

Lastly for the manual guys, I recommend disabling CFCO. I was still having some flaring/dipping when I was in traffic at low RPMs and pushed the clutch in. Disabling CFCO cleared this right up.

Bill I have searched the internet for days to find this, I think this deserves a sticky as the LS2 tunes idle differently from what I am used to in the LS1 when I had one of those. Thank you so much for having an informative post and config, I fixed my problems in under an hour with it.