About to throw in the towel nailing down idle

[5_Liter_Eater]

The car will use the HO spark until speed=0 then it switches to the idle spark table so if they are significantly different that may be it.

You talk about adding 20-30% but that makes me think you really didn't do the procedure or do it correctly. You start off with all zeros for the min airflow, then derive the numbers and subtract I think it's 20% or so, then plot the adaptive idle spark against the table to see how much spark it's adding or removing and edit the table appropriately. Just re-try the last part and post the log.

[boostls2]

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 100 RPM less than your lowest target idle speed.

- 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 ~20 degrees.

- 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.

- 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 table; 650, 800, 1000, 1200, etc. As of 2.23 you cannot type in numbers into this field anymore. I think it stops at 1600 now but I only go up to 1200. Leave it at each cell for at least 30 seconds, 60 is better. 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. Manual guys use the neutral numbers for all gears.

- Using histogram 10 on average (A), plot 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 of the histogram doesn't yield good results.

- Paste the numbers you get directly into the Airflow Final Minimum table for all 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 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 getting smaller. 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 numbers are correct there should be no dipping, hanging or flaring when returning to idle.

So the last part where we log idle adapt advance...when we paste the mult %, we are pasting it in the same table or in another table(s)? I am assuming the same final airflow min table.

I tried this on a 2010 camaro with small cam. I got the maf ltft's good fuel is solid and timing about 25*. It still surges slightly, but not matter how many times i paste mult % from the adaptive advance histo 11, the numbers have come down, but still are sort of jumpy... any other suggestions?

i appreciate these tips!

[5_Liter_Eater]

Yes, same table. Lets see a log of you doing the procedure. It falls in line for me pretty quickly, even when I had a big ass cam.

[smokeshow]

I followed the procedure exactly, and it doesn't seem like it had any effect on the idle at all. It does exactly this, soon as I start it... Starts up and surges to 2k for a moment, then settles and nearly dies and within a few seconds hits target idle RPM. Then if it idles for a few minutes, it will slowly begin to oscillate, first tiny little bits. Within a minute it has a 1k idle RPM oscillation and all of a sudden, it swings high and sits at 3k. I can put it into gear and as long as I'm on the brakes pretty good it will drop to maybe 1800. If I turn it off for a few minutes, this whole thing goes away for a while but comes back later.

I couldn't catch any of that in the log, but I recorded something else. It was difficult to hit target RPM during the idle procedure because commanding RPM in the VCM controls didn't do anything unless I hit the pedal to encourage some RPM first. Only then would the idle go up to where I commanded in VCM controls.

Did I mess up the procedure somehow?

[kjhallex]

I followed the procedure exactly, and it doesn't seem like it had any effect on the idle at all. It does exactly this, soon as I start it... Starts up and surges to 2k for a moment, then settles and nearly dies and within a few seconds hits target idle RPM. Then if it idles for a few minutes, it will slowly begin to oscillate, first tiny little bits. Within a minute it has a 1k idle RPM oscillation and all of a sudden, it swings high and sits at 3k. I can put it into gear and as long as I'm on the brakes pretty good it will drop to maybe 1800. If I turn it off for a few minutes, this whole thing goes away for a while but comes back later.

I couldn't catch any of that in the log, but I recorded something else. It was difficult to hit target RPM during the idle procedure because commanding RPM in the VCM controls didn't do anything unless I hit the pedal to encourage some RPM first. Only then would the idle go up to where I commanded in VCM controls.

Did I mess up the procedure somehow?

Post your cfg file also, what's your fueling look like? Maf and ve table dialed in?

[smokeshow]

Post your cfg file also, what's your fueling look like? Maf and ve table dialed in?

I am using Bill's idle config on page 5. The fueling is close. Its not perfect. Hard to nail down the tune at idle when its surging like that, or idling over 2k. I am running SD, so no MAF.

[5_Liter_Eater]

The log shows you're still way off. It's close ~750 but thats about it. Use histo 11 (idle adaptive spark) and copy and paste (paste special, multiply by %) into the airflow final min table. Then run through the procedure again.

[smokeshow]

I spent a couple hours with the procedure, and I have some issues and some suggestions for improvement. Last time I wasn't getting good results because my ECM (can't speak for others) doesn't allow idle RPM control in gear. In park and neutral it works great. For the auto guys, we'll either need to estimate the in gear values or find a different way to get them. It may be necessary to flash new tune with adjusted idle settings for each RPM idle airflow calibration...

I probably ran through the histogram 11 part of the procedure 5 or 6 times before I decided to speed it up a bit. Since my idle has been surging, using the idle advance timing values at the target RPM isn't a good representation of the amount of timing adjustment needed to hold that RPM because timing is already being pulled there due to the surge pushing above target RPM. SO, what I tried was an average between the target RPM cell and the cell immediately before it. For example if I am working on the 1200 cell and the surge puts the 1000rpm cell at 13° advance but the A value for 1200 is only 5°, I average those two and make a 9% increase to the 1200rpm cells. A couple times doing this led to it finally staying in the 1200rpm cell so I could then use the original procedure to bring it closer to +-1%. This brought the trims in line very quickly as opposed to slowly dragging it in with the target cell only.

While it idled well at each target RPM, startup and touching the throttle at idle didn't do so well. Startup hunts for idle RPM for a second, and revving in neutral hangs horribly even with the idle trims within 1%. If the final idle airflow minimum is almost perfect, what's causing the nasty hang? I am only including the 650 and 800rpm logs; I did them in separate logs because I didn't want leftover numbers messing with the calibration. And of course, the surge and startup logs.

Thanks in advance!

Edit: Looking at it now, I think the surge when I hit the throttle might be because there is no information in the final idle airflow table above 1200rpms. I will try to put some values in there that follow the trends of the other values. Startup is fine until frame 109 where the throttle opens another 10%...looks like it hits the proportional idle airflow and shoots the RPM up. Going to try increasing the enable values...

[MikeOD]

I really like this procedure from post 85, it worked very well for me...I am more curious than anything else...since it seems like everyone is leaving everything above 1200 RPM set to zero (since we can't command higher RPM anyways in the scanner to datalog it), have any of you re-scaled the RPM axis of the Final Idle Airflow Minimum vs. RPM vs. Gear?

I was considering re-scaling it from 250, 400, 600, 800, 1000, 1200, 1600, 2000, 2500, 3500, 4000, 4500, 5000, 6000, 7000, 8000 to something more like 250, 400, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200...Think it's worth it? Think it'd cause problems?

[carlrx7]

not sure if this was ever mentioned, but you should disable closed loop as well. otherwise it will start to surge from the 02's switching.

[jamesbtri]

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 100 RPM less than your lowest target idle speed.

- 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 ~20 degrees.

- 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.

- 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 table; 650, 800, 1000, 1200, etc. As of 2.23 you cannot type in numbers into this field anymore. I think it stops at 1600 now but I only go up to 1200. Leave it at each cell for at least 30 seconds, 60 is better. 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. Manual guys use the neutral numbers for all gears.

- Using histogram 10 on average (A), plot 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 of the histogram doesn't yield good results.

- Paste the numbers you get directly into the Airflow Final Minimum table for all 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 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 getting smaller. 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 numbers are correct there should be no dipping, hanging or flaring when returning to idle.

Bill can you call me please I am getting my ass kicked with this cam and cant get this table to load in histogram 217 840 8426

[LazMan]

Its been a long time since I revisited this thread. Glad to see you are well 5L-Eater.

James: The procedure from post 85 has always worked for me, but I've not been actively tuning anything in years, but ... I'm also unsure why you can't load the histograms ...

... perhaps you could post your config file, and 5L could integrate the histograms and send it back to you?

[Michael_D]

I just walked through this proceedure after finishing VVE cal. I'm perplexed and ecstatic at the same time. Ecstatic that it was as simple as it was. Perplexed that it was this simple and I can't help but think something is wrong. Nothing is ever this simple without some sort of catch....at least with my luck anyway. My base idle can now lope along at 850 verse 950 and I haven't even messed with base timing or adaptive timing yet. The adapt idle error is .1 @ 800, 0 @ 1000 and 0 @ 1200 now. 650 is +5 and I have given up on that cell.... (my cam has 18 deg overlap).

I did have a couple questions...of course. One is, why leave the cells above 1200 rpm at zero?? Wouldn't you want these to be at or slightly higher than what they are at 1200 rpm for those times when the car is decelerating and in neutral? Also, I can not get the engine to idle at 650 steady enough to get good data. If I bump up air flow in the 650 rpm cells to what it is in the 800 rpm cell, it stabilizes. Should I leave the 650 rpm cells the same as the 800 rpm cells, or just bag it and lower the values in the 650 rpm cells?

Thank you Bill for coming up with this technique and sharing it. I have no idea why this works, but I'm not going to look a gift horse in the mouth.

[Midnite Magic]

I just walked through this proceedure after finishing VVE cal. I'm perplexed and ecstatic at the same time. Ecstatic that it was as simple as it was. Perplexed that it was this simple and I can't help but think something is wrong. Nothing is ever this simple without some sort of catch....at least with my luck anyway. My base idle can now lope along at 850 verse 950 and I haven't even messed with base timing or adaptive timing yet. The adapt idle error is .1 @ 800, 0 @ 1000 and 0 @ 1200 now. 650 is +5 and I have given up on that cell.... (my cam has 18 deg overlap).

I did have a couple questions...of course. One is, why leave the cells above 1200 rpm at zero?? Wouldn't you want these to be at or slightly higher than what they are at 1200 rpm for those times when the car is decelerating and in neutral? Also, I can not get the engine to idle at 650 steady enough to get good data. If I bump up air flow in the 650 rpm cells to what it is in the 800 rpm cell, it stabilizes. Should I leave the 650 rpm cells the same as the 800 rpm cells, or just bag it and lower the values in the 650 rpm cells?

Thank you Bill for coming up with this technique and sharing it. I have no idea why this works, but I'm not going to look a gift horse in the mouth.

I am interested in this also? Does the same procedure work for LS3 engines

[5_Liter_Eater]

Glad you're liking it.

The newer versions of HPT don't even allow you to command anything higher than 1200 in VCM controls. You could do your best to modulate the throttle to try and get the next upper RPM data but the reason to zero it out is to try and get the RPM to come down faster rather than how it slowly comes back down as it is stock. Not sure how well this works but if there are problems with it flaring or dipping at ~1200 then you could try aned populate the upper RPM cells or just extrapolate the next values.

If you can't get it to idle as low as 650 then I'd just extrapolate the data for that cell also. This is what I do for the 400 cell.

The reason I don't mess with the adaptive idle proportional or integral is I don't find that the stock values need tweaking. Only when the tune is scaled 50% for large injectors do I need to play with it. I've tried scaling it along with all the other airflow/airmass tables but it didn't seem to like it.

This procedure should work for all the 4th gens (LS2/3/7/9).

[Midnite Magic]

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 100 RPM less than your lowest target idle speed.

- 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 ~20 degrees.

- 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.

- 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 table; 650, 800, 1000, 1200, etc. As of 2.23 you cannot type in numbers into this field anymore. I think it stops at 1600 now but I only go up to 1200. Leave it at each cell for at least 30 seconds, 60 is better. 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. Manual guys use the neutral numbers for all gears.

- Using histogram 10 on average (A), plot 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 of the histogram doesn't yield good results.

- Paste the numbers you get directly into the Airflow Final Minimum table for all 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 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 getting smaller. 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 numbers are correct there should be no dipping, hanging or flaring when returning to idle.

Okay is 850 rpms reasonable for a 235/247 camshaft on a 114LSA with a 416 cu.in engine along with the F1A procharger?

Also I have my idle spark set at 20 degrees and the procedure work well in park/neutral. However I can't seem to command different idle RPM while in gear?

Labels 200 400 600 800 1,000 1,200 1,600 2,000 2,500 3,000 3,500 4,000 4,500 5,000 6,000 7,000 8,000
1st Gear 10.615 10.615 11.736 13.143 14.641 18.707 19.393 20.686 22.627 24.564 26.506 28.439 30.381 32.322 36.203 36.203 36.203
2nd Gear 10.615 10.615 11.736 13.141 14.641 18.707 19.105 20.379 22.291 24.199 26.111 28.018 29.930 31.842 35.666 35.666 35.666
3rd Gear 10.615 10.615 11.736 13.141 14.641 18.707 18.682 19.928 21.797 23.664 25.533 27.398 29.268 31.137 34.875 34.875 34.875
4th Gear 10.615 10.615 11.736 13.141 14.641 18.707 19.393 20.686 22.627 24.564 26.506 28.439 30.381 32.322 36.203 36.203 36.203
5th Gear 10.615 10.615 11.736 13.141 14.641 18.707 19.619 20.928 22.891 24.852 26.814 28.771 30.734 32.699 36.625 36.625 36.625
6th Gear 10.615 10.615 11.736 13.141 14.641 18.707 19.619 20.928 22.891 24.852 26.814 28.771 30.734 32.699 36.625 36.625 36.625
Neutral 9.063 9.063 10.020 11.723 13.650 17.137 20.400 22.031 23.662 25.299 26.928 28.561 30.191 31.820 32.641 32.641 32.641
Reverse 10.615 10.615 11.736 13.141 14.641 18.707 19.105 20.379 22.291 24.199 26.111 28.018 29.930 31.842 35.666 35.666 35.666
Park 9.063 9.063 10.020 11.723 13.650 17.137 20.400 22.031 23.662 25.299 26.928 28.561 30.191 31.820 32.641 32.641 32.641

[Michael_D]

Glad you're liking it.

The newer versions of HPT don't even allow you to command anything higher than 1200 in VCM controls. You could do your best to modulate the throttle to try and get the next upper RPM data but the reason to zero it out is to try and get the RPM to come down faster rather than how it slowly comes back down as it is stock. Not sure how well this works but if there are problems with it flaring or dipping at ~1200 then you could try aned populate the upper RPM cells or just extrapolate the next values.

If you can't get it to idle as low as 650 then I'd just extrapolate the data for that cell also. This is what I do for the 400 cell.

The reason I don't mess with the adaptive idle proportional or integral is I don't find that the stock values need tweaking. Only when the tune is scaled 50% for large injectors do I need to play with it. I've tried scaling it along with all the other airflow/airmass tables but it didn't seem to like it.

This procedure should work for all the 4th gens (LS2/3/7/9).

Thank you!

[Midnite Magic]

Seems the E38 in the 2010 Camaro doesn't allow commanded RPM in gear or reverse. Maybe figure out the Park / Neutral table and add a percentage to the gears and reverse.

[5_Liter_Eater]

I think I said a ways back that I had never tried it on an automatic. I'd pull the e-brake and put it in drive. Then I'd scale the whole in gear table up or down until it jives.

[5_Liter_Eater]

I Updated some verbage and added recommendation to disable CFCO on the main post (#85).