Vems Idle Troubleshooting

[a4kquattro]

do you know of someone using 1.1.44? I need help fast because i need the car tomorrow!

if you need to go back to 1.1.27 follow the following procedure (the issue is that 1.1.44 floods the serial line with the AIM communication protocol, which prevents the firmware reset from working right):


1) edit the file 'upload-firmware12x12.bat' in the 1.1.27 megatune folder. Change the line that starts with: tools\megaloader.exe to read like so:

tools\megaloader.exe firmware\vems12x12.hex -wE -c com1

where "com1" is whatever your serial port is.

2) turn ecu off. Make sure no megatune or other programs are running that might try to use the serial port
3) shove a bent paper clip between pins two and three of the serial connector
3) power on ecu. wait 3 seconds. remove paper clip and connect serial cable to your computer.
4) run the upload-firmware12x12.bat file. It will ask you to press a key to continue etc. The process should complete successfully.

Try this for a 1.1.44 audi basemap. Configured for 12x12 tables, 60lb/hr fuel injectors, GT3071 turbo, high output TTL coils. Cam hall inverter.

http://www.efiexpress.com/downloads/...ll_ttl_ls2.msq

[A80Avant]

I have been experimenting with the idle control and PID type settings on VEMS.Since most people who go for an aftermarket ECU are basically not much interested in having an OEM like idle and are mostly concerned about good runnning and perfomance figures, i thought id spend more time with idle and the understanding of settings for it.

Unfortunatelly Peter's settings or anyone elses for that matter, dont really work for me and i came to realise that noone elses settings will be adequate simply because each one uses different map around idle.Different ignition timing, different VE table, different parts in the engine etc. Therefore each one's settings on idle are unique,hence the difficulty of setting them!

1)Ignition based timing is the easiest way to go which will provide good idle on cold,good idle on warm, minimal oscillations and not much fuss. Downside is that as you have to retard ignition quite a bit around that idle area,you get higher EGTs on that spot.
Solution? Give it more enrichment and problem solved... HOWEVER, that wont be nice for MOT people now will it? Again if i wanted that area to be spot on,i would just do a simple change on the VE map, and go for MOT. simple.

2) When you take the ISV valve into action,EGTs drop very fast and very easy.So you are fine there,but on the other hand you are left with the PID settings to control the ISV valve as best as possible which makes matters difficult but not impossible.Motronic can do it, and possibly uses the same type of control.When you combine the ISV + ignition based timing, you end up with the best result IMO

PID stands for :
P: proportional: reaction to an error
I: intergral: reaction to sum of errors over time
D: Derivative: rate at which an error has been changing

It may be that the ISV is actually using PI or PD to control it, rather than all 3 factors.

Basically it goes like this: Set of idle: 900rpm
If the idle is not @ 900rpm a change must be done to correct.High (P) value will correct that error fast.If (P) is too high then it produces and oscillation.
(simple example is a accel.depression when on idle. Idle drops below the 900rpm mark,then the P value will force it to regain the set point of 900rpm.)

I: will be combined to the P value to give a correction to a sum of errors over time. If the I is too high, then the correction overshoots the setpoint!
D: slows the rate of change of the controller's output.Basically it reduces the combination of the P+I reaction.(at least that is how i understand it).However, too high D will create noise and enhance oscillation.

On cold start ISV is fully open to help with the added air+fuel to keep the engine going. As the engine warms up, then the idle needs to work less and less to keep the idle stable, BUT it still works, it never stops,otherwise in motronic on a warm engine, you wouldnt stall on traffic lights when your ISV was faulty.

So far i have realised that setting the DC of the ISV to 10 on warm engine(>71C) gives me a rock steady OEM like idle, even with PID settings set to zero.This happens because the idle is primarily controlled by ignition timing, BUT the ISV is still there to keep the EGTs down.However when i turn AC on as well as all other electrical equip. then the idle wobbles when there is a change and goes to stall.

Once the laptop gets a fresh power energy, this will be my next task.Setting the PID. The good thing about the PID is that at least on a warm engine if the DC of the ISV is small,their numbers generally have less effect overall. On higher DC of the the ISV then their numbers create larger reactions.

Also since there is no differentiation between PID for cold and PID for warm engine status, i believe that the settings should work for either....

more tests to be done...

[A80Avant]

here are my idle settings:

[GazzaG60]

how did you get to 10.

did you take the aic DC and add 2% from realtime?

[GazzaG60]

what are your ignition based idle settings.

[A80Avant]

well they are posted above. what else do you mean?

i found that these settings although very good on warm engine,they are not good for cold engine,so basically i took the ISV more out of the equation on colder engine temps. so on the pwv reference table it goes from the 15.5C and down : 30-18-12-10-16

also brought the ignition advance settings up to 14deg instead of 10.

more tests to follow..

[GazzaG60]

in megatune go extras then spark based idle control. if its enabled there are target rpm settings.

you haven't listed those above.

[GazzaG60]

i like your enthusiasm towards getting this right too.

best of luck. i have settled with what i have for now. a little lazy am i.

[A80Avant]

that is the first window i have posted.Under extras/idle settins that is all i get there.

maybe it is altered on 1.1.44 version.

i have 1000rpm cold and 900rpm warm and idle based on 15deg i think +/- now

i will look again tonight

[A80Avant]

well after the 1.1.44 being unstable on other areas i switched back to the official 1.1.27 beta6 version and started working on that with the 16x14 tables. It seems to be much more stable now.