About to throw in the towel nailing down idle

[kllrvet]

I think I'll need to refer to this later

[scphilli]

I am trying to walk through this and can't seem to find anything called the "idle spark table". Is this the "Idle spark advance"? If so, Base or Coast down?

Thanks in advance.

[Higgs Boson]

make them match

[scphilli]

Thanks for your patience, but I don't want to assume I understand your response and make an error. Not sure what "make them match" is in reference to.

The instructions in post 85 called for putting the corresponding values from the HO table into the idle spark table. I could not find a table called "idle spark table" and the instructions made no mention of Base or Coast down, so I was not 100% sure I was looking at the right table.

[Mez]

Thanks for your patience, but I don't want to assume I understand your response and make an error. Not sure what "make them match" is in reference to.

The instructions in post 85 called for putting the corresponding values from the HO table into the idle spark table. I could not find a table called "idle spark table" and the instructions made no mention of Base or Coast down, so I was not 100% sure I was looking at the right table.

Go to Spark > Idle Spark Advance > Base.

There are differences in opinion here. On my 2005 Corvette with a mild head/cam set up, I left the High Octane spark cells almost stock and left the idle spark base and coast down tables close to stock. Just added a couple of degrees. But a more radical set up may like more advance at idle. Mine tune works well with 17 degrees at base idle and coast down tables and 31 degrees on the High Octane table.

My understanding is the High Octane table sets the ceiling on ignition advance. Then stopped, the idle base timing table takes over and it uses the idle over and under speed tables to add & subtract advance to keep the idle RPM reasonable.

Depending on the amount of torque your head/cam set up makes at idle, advance can make a huge impact on keeping the idle RPM good. Here is what you have to understand. If, for example, your engine makes its maximum torque at 26 degrees at 800 RPM, then any air flow or timing changes have a lot more impact on idle RPM than, say at 16 degrees. So what you may want to try is set the base idle timing between ~16 degrees so it is less sensitive to any airflow or timing changes. It also give the timing over/underspeed tables room to work. A big, nasty cam with lots of overlap may need 25-30 degrees in the base idle table so you may need to experiment here. I don't know what your set up is so I can't give you a hard and fast rule.

All of this is fine IF the VE and MAF tables have been calibrated at idle. Your air flow tables must spot on first before tweaking timing. If air flow is not right you will end up chasing you tail.

This is not just me speaking but it is also the advice of the experts including Greg Banish.

[scphilli]

Thanks Mez! I am just trying to learn now and do not plan on changing anything for quite some time. Your post is very helpful.

[02GTP]

Can someone take a look at my tune and give me some pointers? It idles fine 80% of the time but occasionally right after startup and sometimes coming to a stop the idle will flare and dip a bit, 1200-600. Like I said, not all the time but something is still wrong. Car is a full bolt on 06 M6 GTO with a 231/235 .617/.620 112+4 cam. Thanks.

[5_Liter_Eater]

Can't really tell anything without a log taken with this config. Have you tried the procedure?

[02GTP]

I'm having trouble with the histogram. My 10 and 11 are blank so I guess I will have to try to custom make a histogram.

[02GTP]

Here is a log of the flaring/dipping. This is coming off the highway on an off ramp coasting in neutral.

[5_Liter_Eater]

It doesn't contain what I need. Here is another config that uses MAF instead of dynamic airflow. You should be able to run through the procedure with it, at least histo 10 will work, I don't see why 11 wouldn't.

[02GTP]

Is there supposed to be something configured on 10 and 11? Cause I have the beta version I bought about 4 years ago and those are both blank. I think after looking at the log its timing related, the timing jumps to 29* or so and thats when it acts up. I will try to fix that and see if it helps.

[5_Liter_Eater]

Uh, are you tuning the car that your screen name is? Cuz this procedure is not gonna work for that.

If you're working off a 4 YO beta you need to upgrade. Contact [email protected]

[02GTP]

No its a 2006 GTO. When I use the VCM controls and turn the spark idle control on/off the idle doesn't change so doesn't that mean my RAF table is pretty good or no?

[5_Liter_Eater]

I donno man.

[MikeOD]

- 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.

After I do this first step and reflash...my adaptive advance winds up at 0 the first time...but the car has issues with idle still. Am I doing something wrong? I'm making sure fuel trims are off and reset while I do this.

[DSteck]

Shoot me your cam specs and tune to [email protected]. A log of steady state idle wouldn't hurt.

[MikeOD]

What do you want me to log at idle?

[DSteck]

The basics. Rpm, spark, fuel trims, etc %, dynamic airflow, dynamic cylinder air, etc.

[kj217]

***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.

does this work with 09 CTSV with E67?
i opened the config file and found histograms 10 and 11 unsupported,, any work around?
car is an A6 and has a cam of -5 overlap,, idles good except for 100rpm fluctuation which shakes the car when D/R engaged,, is that accepted from such a cam?