About to throw in the towel nailing down idle

[MikeOD]

Be careful reducing the max...it might not be able to start/idle when it's cold out and it's sat overnight.

The minimum idle airflow table is the minimum throttle angle (after some math to translate it to an angle from that airflow) with an RPM axis...the max it the max.

That's why you see cars idling with extremely low spark advance if they have too much airflow in the minimum table...the PCM can't close the throttle enough because of the minimum, so it has to pull spark to bring the RPM down.

[daniel76309]

Thanks. I haven't been doing much with it lately. It could probably be better, but it basically idles ok as it is--mostly I am trying to make sense of it all.

I did try reducing Max Idle Area from 2.51 to 1.5, and it didn't seem to have any effect, i.e. I still couldn't command idle speed lower than about 850 with the scanner, so I gave up on it for now. I can also set a lower target idle speed and it has no effect. I used to think it had to to with Airflow Final Minimum being too high, but obviously that isn't the case since it acts the same way zeroed out.

[MikeOD]

Thanks. I haven't been doing much with it lately. It could probably be better, but it basically idles ok as it is--mostly I am trying to make sense of it all.

I did try reducing Max Idle Area from 2.51 to 1.5, and it didn't seem to have any effect, i.e. I still couldn't command idle speed lower than about 850 with the scanner, so I gave up on it for now. I can also set a lower target idle speed and it has no effect. I used to think it had to to with Airflow Final Minimum being too high, but obviously that isn't the case since it acts the same way zeroed out.

Vacuum leak?

[daniel76309]

Vacuum leak?

Thank you, I will check for that!

[Niemer]

How did you auto guys go about getting data in gear? Just brake and throttle?

[YellowSS]

Anyone figure this out? I to have hanging idle @ 1500 rpms then settles to 975, but I also have lazy 02 sensors readings and at 4000 plus rpm its commanding 100% duty cycle of fuel. The problem seems to go hand and hand. I have noticed one thing when data logging I see the lazy 02 and the too rich conditions at 4000 rpm causing hesitation from being to fat. Not sure by coincidence but when driving around with a tech scanner the problem went away 2 times.

[Pekka_Perkeles]

Anyone figure this out? I to have hanging idle @ 1500 rpms then settles to 975, but I also have lazy 02 sensors readings and at 4000 plus rpm its commanding 100% duty cycle of fuel. The problem seems to go hand and hand. I have noticed one thing when data logging I see the lazy 02 and the too rich conditions at 4000 rpm causing hesitation from being to fat. Not sure by coincidence but when driving around with a tech scanner the problem went away 2 times.

Please make a new thread with your TUNE and LOGS.

It is way easier to help when there's just a single thread, not many with same questions.

[pganci]

I came across this thread and it sounds like the problem I am having. My spark advance at idle and when coming off idle when first started looks like a saw tooth. In order to make the vehicle drivable I had to set the Spark>Idle Adaptive Spark Control>Spark Limiters>Spark Ramp Out>Spark Minimum table to 12 degrees. With that the spark advance will drop to 12 degrees and just sit there until I throttle through it which results in sputtering. Once I am driving for a while the problem seems to go away but if I shut it off even just for a minute the timing issue is there until I drive for a bit again.

Attached is my tune and a scan I ran on my way to work, I would really appreciate some input and direction to clean this up.

I posted up a few times before but no one responded so hopefully replying to this thread will help.

Thanks

Paul

[Speedforhire]

pganci...........I can't get your file to open with Version 2.24.1079...........you using the new beta?

[pganci]

pganci...........I can't get your file to open with Version 2.24.1079...........you using the new beta?

Yes, I'm using the latest beta version.

[pganci]

pganci...........I can't get your file to open with Version 2.24.1079...........you using the new beta?

Here is the tune in version 2.24 in case that is the reason no one is responding.

I forgot to mention the idle surging basically goes away once I reach 175 degrees from a cold start or driving for about 5 minutes from a warm start.

[pganci]

What's a guy got to do to get some help...

[GHuggins]

Holy.... How do you not have a self cruise problem??? How about starting by knocking that min air flow table back down around stock or maybe a touch under... If it's still there, then go into your idle advance timing and knock the entire table down to where you only have around 7 or 8 degrees in idle areas, then go to your main timing table and increase it until it's pretty close in the idle area to your off idle or 1200-1600 rpm ranges. Make this timing number the same from 1000 rpms down and down to 20g/cyl then remove 1 degree in 24g/cyl then get close around those corresponding cells. If it's still surging... Go to idle proportional and increase these two rows by 1.1 and then go to idle integral and increase "or I guess decrease" by multiplying by .5... Then get back to us. The min airflow and timing should more than likely fix it....

Hope this helps.

[pganci]

Holy.... How do you not have a self cruise problem??? How about starting by knocking that min air flow table back down around stock or maybe a touch under... If it's still there, then go into your idle advance timing and knock the entire table down to where you only have around 7 or 8 degrees in idle areas, then go to your main timing table and increase it until it's pretty close in the idle area to your off idle or 1200-1600 rpm ranges. Make this timing number the same from 1000 rpms down and down to 20g/cyl then remove 1 degree in 24g/cyl then get close around those corresponding cells. If it's still surging... Go to idle proportional and increase these two rows by 1.1 and then go to idle integral and increase "or I guess decrease" by multiplying by .5... Then get back to us. The min airflow and timing should more than likely fix it....

Hope this helps.

Thanks for the reply GHuggins. So just so I am following, decrease the minimum airflow table to around stock, reduce the Idle Spark Advance by 10 so that I am at 8 degrees in the idle area and increase my main spark advance in the idle area so that it is like 1200-1600 range in the idle area?

[GHuggins]

Yes, but you'll want your idle timing in your main spark table to be withen a degree or two of what the 1200 range is...

How did this go?

Also forgot to mention you really really need your injector data to be right. I haven't looked at it, but very important for this.

[pganci]

Yes, but you'll want your idle timing in your main spark table to be withen a degree or two of what the 1200 range is...

How did this go?

Also forgot to mention you really really need your injector data to be right. I haven't looked at it, but very important for this.

I only had chance to do a quick change to the airflow and timing and a initial quick test drive the timing was still taking a dive when I let off the throttle, I also put the minimum table back like factory instead of 12 degrees across the board. I think the surging was not as apparent but with the timing diving it was hard to tell and I didn't have time to keep playing with it.

The injector data should be correct using injector dynamics data for the ID850's.

I don't have a factory tune to look at for the 2009 Express Van, I was only able to find a 2010 Express Van in the repository to reference factory settings to and it was a flex fuel and I don't know how different that can be. The shop that did the LS3 controller conversion gave it to me saying it driving like a stock vehicle and my initial drive was bucking and sputtering, anything but a stock feel. I took it home anyways to take notes on everything and found that they had the drain cock open on the catch can so they were trying to tune with a massive vacuum leak. They have since gone closed their doors so I am left to try and reverse engineer what they did.

I am going to try the idle proportional increase and idle integral decrease tomorrow and see what happens.

I really appreciate you taking the time to look at the tune, I have posted 3 times before with no response.

[GHuggins]

Fueling makes a pretty big difference too, especially if they tuned it with a big vacuum leak. Do you have histograms for your MAF and VE setup to datalog and make corrections? Overly rich can cause all sorts of problems... Sucks knowing you paid someone to do this, then they couldn't bother to half way attempt to do it correctly. Been there, done that. Grew from it...

Add (Fuel Trim Correction) pid to your datalog table and input this equation....

((([PID.6]+[PID.8])/2)+([PID.7]+[PID.9])/2)))

This adds and then averages Long term and short term fuel trims between the two banks. Makes tuning all of your driveability areas much easier and quicker. You need a wideband of course for WOT, but this will at least allow you to get fueling very close, very fast and watch out for the rich after flash problem. Allow at least 15 minutes of drive time before you start datalogging corrections, otherwise you'll be fighting yourself.

[pganci]

Do you have a config file you can share with me, I have not added any PID's before.

[GHuggins]

Try this one... You will need to configure it for your wideband if you ever get one or have one. You'll have to save it to your HPTuners - VCM Scanner - Histograms section then open your scanner and click open config tab. You will need to disable dfco in your tune then drive it around for about 30 minutes to get good data. You might even want to go into the histogram and click on setup tab and change cell hits required to 20 to 35 for better averaging. Cell hits on mine is set very low because I can better control load and throttle on the dyno.

Remember your MAF transfer curve should be a smooth climb. Look at the line before you start tuning or rather the line in a known good tune. You don't want dips or mountain spikes on it. Doesn't matter if fuel trims are plus or minus 7 in these areas at first. It gets closer and closer the more you work it. Start pasting special half percents right around +-2 to 3 percent will help too.

[pganci]

Thanks, most of the Histograms in that config say its not supported with the current loaded parameters. The few changes you recommended unfortunately did not help, instead of surging the idle was dropping below the commanded idle and about to stall when I would drive and let off the throttle.

Lost my power steering pump this morning so I am going to be down till the weekend.

It never ends...