Tuning suggestions for idle VE table
 

Hi,

today I got my car running for the first time with the MS3. Now I have to tune some of the new features . like idle VE table.

As I can't tune that via VEAL (or can I?) how do I tune that the right way? (Is there a correct step-by-step way?)

Thanks!

Maybe I have to make my question a bit more understandable.

Are you using the idle valve test feature to get into those specific cells
in the idle VE table or how are you filling all edges of this table?

I wouldn't use VEAL since the o2 response at idle is not always reliable.

Here is how I tuned mine:

0. turn off O2 feedback below 1500 rpm! Also turn off EAE for tuning idle VE.

1. Warm the car up most of the way.
Keep a close eye on MAT and CLT and make sure they are within a normal range or you will get inconsistent results. Idling car gets hot and MAT enrichments will make you crazy. Set up a gauge on the TS page that warns you when the car is getting too warm from heat soak or use Braineack's inverse MAT correction graph and set MAT correction to "50". It'll still be tough outside "normal" idle temps so be aware of it.

2. set your idleVE table load and rpm points to some that make sense.
I use 25, 35, 45, 55 kPa. That covers just below idle to just above idle with A/C.
For RPM I use 700, 850, 1100, 1350. Same reason. I want to know my AFR when I have an idle dip is going to be still in that table. And I want A/C and slight flares in idle speed covered.

3. start with some values similar to the cells in your main VE table if you don't have anything in here yet. maybe 3-5% richer just to start?

4. you can use pwm warmup to get the idle speed steady if you want. just dial up the duty cycle to put you in the center of the RPM cell from left to right. make sure "Idle VE" indicator is lit in TS.

5. Use various loads (parking lights. headlights, defrost, cabin fan, a/c, etc) to get close on load. You can also move load around a little bit with timing advance / retard. more advance should lower load slightly if you're close. You may want to set your radiator fan to either be full ON or full OFF while you're doing this to remove the automatic variable (if it changes your load because of electrical load).

6. Start in the CENTER of a given load/rpm cell and < > it up and down until you get close to your target. I would start by aiming for 14 or 14.3 AFR for most cells and then if you need to add/remove fuel you can select them all and use the * (multiply) button to add or subtract about 1% at a time (i.e. multiply by 1.01 or .99--never more than 3% though--and wait a good 10 seconds for it to stabilize).

7. dont forget to check your MAT enrichments aren't adding or removing fuel!

8. Return all your idle settings back to closed loop and your fans to come on automatically again like it was before. Turn off the car and let it sit for a few hours so it cools off.

9. Start it back up and see where you ended up. I let Idle VE come into play at fairly low temps because it's tuned pretty well. No sense in waiting until the car is almost warm--you've got WUE and ASE to deal with a cold car.

10. flip some of the above loads on and off and see how the AFR reacts.

Thanks a lot - that was just what I was seeking. Should be in the manuals - maybe we should give this to James at msextra to have a look at it and add it there!

MAT corrections are already driving me crazy (and I am already using the MAT correction table and a correction factor of 50%)... was like 8°C outside today - dialed in the normal VE table cells at idle without the IDLE VE to ~14.5 - started the car 5min later - I get 15.6-16.0 AFRs... (MAT was at 15° now) dammit - I hate that. I already had that at the DIYPNP... *rant end*.

But thanks again for that nice writeup.

sure thing. I'm sure others have similar ways to do it but that's what I'd do. It's hard when you're fine tuning and everything is working normally because you get oscillation and the little trace dot wont stay still and you have to guess which cell is causing the leanness or richness because there's a huge lag.