Sudden switch in idle afr

[pyrosanltd]

Hello to all,

I am thoroughly stumped up until now I have had a nice idle of 14.5 AFR at ~ 45 load 940 RPM , Last night I took the car for a spirited drive with VEAL running in the background and made some pleasant progress in my tune. I pulled in last night let the car idle for a good 10 minutes then saved my tune. This morning when starting up it pegged rich at 11.5 to 10 at idle I expected this because my WUE was not changed since my changes last night so I let it go and sat waiting in the driveway for the engine to warm up and dis enguage WUE. well WUE stopped and the AFR continued to stick at 11.2 / 10 ish afr with a 1400 RPM for idle, I have an adjustable FPR that I have had set at 43.5 PSI double checked the reading and it was stable. I ran VEAL this morning to allow me to get to work with out pissing fuel everywhere when I got to work the VE table leaned out by quite a bit. My question is what would cause such a pronounced change in fueling with MS ? literally the only thing changed was the ve table but even with the reduction of the ve values I have really low number on the table now. the car idles smooth and drives smoothly at this point I am stumped as to why such a change in fuel needs.

My MSQ and logs of before and after are located at my google drive

https://drive.google.com/folderview?id= ... sp=sharing

the 2014-7-24-19.23.15.msl is how the tune behaved before the veal session

the 2014-07-25_08.10.08.msl is what I have now as of this morning

I have uploaded two more files, The Ve tables before and after hopefully this will help.


and thoughts would be greatly appreciated.

Thank you,
John Gates

[pyrosanltd]

If this helps I forgot to mention the setup

700CC injectors
43.5 psi at regulator
LS1 coils

MS3 with ms3x full sequential

the motor is a volvo b21FT stroked to 2.4 liters with a ported 8v head and TD04HL-15G

If there is any further information I can provide please let me know.

[wrenchdad]

Just a quick guess, but sounds like heat soak to me, you drove the car then stopped for 10 minutes SO maybe VEAL adjusted for the higher MAT readings?

Or are you saying that after the changes to VE, it is now right on AFR but with much lower numbers in the table?

Wd

[slow_hemi6]

Never allow veal to adjust your idle cells. Always get them right manually and lock them out. You may not be aware but when decelerating the engine will sweep through the cells used for idle but because of your decelleration veal will see those cells as lean when they are actually fine.

[wrenchdad]

I disagree, you can use VEAL to adjust your idle cells THEN smooth it out manually then block VEAL from changing it after that. It's one way of doing it, but of course there are always different ways to get the same results

Also don't know where you idle but I have never decelerated thru my idle area of my table, I would have the clutch in before it got there, may just be me......

Later wd

[pyrosanltd]

Thanks to all of you regarding the comments regarding how to tune idle, This is helpful. After getting my car home I saw my voltage dropping rush hour traffic tends to take longer allowing me to see my voltage gauge dropping, I noticed that as the voltage dropped the mixture would become richer. found that my Exciter wire loosened up and fell off. once I figured this out I waited for my engine to cool down and hooked it back up ... instantly everything was back to normal .... well normal is it could be. While we are on the topic of idle tuning and smoothing of the idle area, I am rather inept in the smoothing process possibly some examples of before and after would be helpful.

Thanks,

John

[elutionsdesign]

While we are on the topic of idle tuning and smoothing of the idle area, I am rather inept in the smoothing process possibly some examples of before and after would be helpful.

I like to first make sure you're idle is in the first two lefthand columns in the table and first two or three bottom rows in the table, a group of about six or so cells. I've seen a lot of logs where the idle is WAY up the MAP due to big cams or whatever, you can adjust the bin values for both MAP (or load) and rpm so use that to box your idle into the lower left corner of the table. As mentioned above once you get these set you don't want to allow VEAL to mess with them, set the min rpm to 1000 or so under the advanced settings tab. Then I usually tune to the desired AFR by incrementing these "idle" cells by one or at most 2 VE unit(s) going up and to the right. So first column, bottom up, say 30, 31, 32 then the next column to the right of that 31, 32, 33. Something of that nature. Always gives me a rock solid idle, the basis of tuning is from a rock solid idle.

[wrenchdad]

You might want the left most column to be set to a RPM that is below your target idle, as in if target is say 900, then the left most column could be set to something like 600rpm, do this in both your fuel and spark tables, the reason for this is to use those columns for stall recovery.

Just my 2 cents worth,

Later wd

[pyrosanltd]

"I like to first make sure you're idle is in the first two lefthand columns in the table and first two or three bottom rows in the table, a group of about six or so cells. I've seen a lot of logs where the idle is WAY up the MAP due to big cams or whatever, you can adjust the bin values for both MAP (or load) and rpm so use that to box your idle into the lower left corner of the table. As mentioned above once you get these set you don't want to allow VEAL to mess with them, set the min rpm to 1000 or so under the advanced settings tab. Then I usually tune to the desired AFR by incrementing these "idle" cells by one or at most 2 VE unit(s) going up and to the right. So first column, bottom up, say 30, 31, 32 then the next column to the right of that 31, 32, 33. Something of that nature. Always gives me a rock solid idle, the basis of tuning is from a rock solid idle."

Elutionsdesign,
The goal is to have my idle in the two left hand columns. The cam is a mild cam specs are as follow Intake Lift: 10.5mm Intake Duration: 254 degrees at .020" Exhaust Lift: 11.96mm Exhaust Duration: 270 degrees at .020" Lobe separation: 112 degrees. As of yesterday evening I was fortunate enough to get in touch with a coleauge that has the same engine configuration as I do, I have since made adjustments to my AFR targets and the ignition timing which has allowd for my idle to obtain a lower MAP value Your example on the smoothing will be applied with the new configuration. As for locking out VEAL would you be able to attain the same results by selecting the cells within VEAL and locking them? Thank you for the suggestions and I look forward to seeing how the car handles the adjustments!

"You might want the left most column to be set to a RPM that is below your target idle, as in if target is say 900, then the left most column could be set to something like 600rpm, do this in both your fuel and spark tables, the reason for this is to use those columns for stall recovery."

Wrenchdad, Thank you for the input regarding my rpm scale on my VE, AFR , IgnitionTiming. I belive that I have this already built into the tables, From what I understand is this is documented within the msextra documentation along with many other threads on this forum.

I will upload my new MSQ to the google drive, I will also keep uploading my logs as I progress. Thank both of you for your input I greatly appreciate it and look forward to making further improvements on my tune as well as learning how to dial in my tables !