Audi RS2

[AVP]

yes indeed. i was just trying to figure out a way for the IAC valve to work more and react more in warm engine rather than ignition timing doing all the work and rising the EGTs for it.


if i use something like 18deg of ignition timing for the idle bin,and then allow the ISV to still interact,to an extent that both working together do the job, i think that should do it.

reading through the PID on wiki now...

[AVP]

Finished!!!

well

questions: What do the numbers represent in the P/I/D sections? I assume it is just a solid number,and it does not represent time in min or sec for example.

In VEMS the terms intergral incr/decrease and integral deadband(rpm). Should i assume that these are values that are having to do with the I value and the limit to which the I can take in values?

Also the IAC deadband basically is a number that we would like the IAC NOT to work in, what should that number be? WHEN do we NOT want the ISV valve to work?

ALso my other query is how should the IAC ref table should look like?These are % of IAC position,which means....?  Im just thinking that this is the amount of IAC implementation to the idle along with the ignition timing. Am i right?

Finally am i right in thinking that when the car is cold and we start it up, we want the IAC to work over time and as the engine warms up we want it to work less?

cheers

[AVP]

I found some info from the VAGCOM diagnostic about the Audi IAC which may help.BUT i need someone to 'translate' what those values could mean.

I have:

1) IAC operating range  :  121-135
2) IAC curve zero point :   70-125
3) IAC load adjustment :  123-137
4) IAC curve control    :   41-61


does anyone have an idea of what those values would mean and how those can be translated into the PID type of control we have in VEMS?

[rob@vems.co.uk]

As I understand it the values effect the change of solenoid duty.  The reference table as you suspect seems to help the controller react more when its cold and then reduce changes as things warm-up.

The rest is trial and error - and I've never played much with a idle control solenoids as the cars I've played with are track only and when a solenoid has been fitted they've been happy with simple on/off type.

[AVP]

i had another go today. Im pleased with the results on the IAC control so long as i set the DC on the 71C bin at 10.This basically tells the IAC to become less involved with the whole procedure.

PID is a bit tricky to configure,but the less the IAC is involved,the less you have to play with.At least that is what i realised today.On normal driving as well as not using AC or any other electrical part on the car, it seems that PID can all be set to 0 pretty much.Cause the idle is mostly ignition based. However, on 15deg of advance and IAC DC:10 i do get a bit lower EGTs as i wanted

However, the solution may as well be somewhere in between, as when i tried to have IAC DC= 40 on warm engine, i had managed to get EGTs down to 400C and semi decent IAC control through PID.So a combination of both will give the good result.

Basically i now have to see how all these changes affect the cold start and then see the PID settings i need to make for AC/electrical devices control,as by the end when i tested it it seemed to jump around a bit, but having said that i had PID settings to 0 at that time.Even with that and AC only on, it seemed to be very stable.Without it, Idle went directly to the set point of 900rpm!

Happy with that!

A small note on accel.enrichments.After being happy with the idle for a while and VE/spark were ok i tried again on the accel.enrich.

When i press the accel with various velocities, even on adj. of injector pw to 0.1 or 0.2 i still get a 10-15 drop in EGTs before they start to rise again. Im trying to understand if this means that it needs more or less fuel to react faster!

[gunni]

Your lambda will tell you not EGT´s

[AVP]

well lamda goes both ways anyway. first lean,then rich.Hence the EGT drop i gues.

my problem with accel.enrichment is the same as everyone elses. Unfortunatelly is way far than the accuracy and feel of the original ECU. Im not sure if VEMS with just 8 bins can cope with all that is required for it.

Also, i noticed that under Tuning/acceleration RPM vs Amount, all my RPM banks read 100 and the amount banks 0. Why is that? what does that map represent?

[AVP]

by the way, when i tried to look into what is happening on motronic for acceleration enrich. it seems that whenever you depress the accel. EGTs do not drop so much,as it happens in VEMS.

SO basically i think im having too much enrichment with long duration??

[gunni]

well lamda goes both ways anyway. first lean,then rich.Hence the EGT drop i gues.

my problem with accel.enrichment is the same as everyone elses. Unfortunatelly is way far than the accuracy and feel of the original ECU. Im not sure if VEMS with just 8 bins can cope with all that is required for it.

Also, i noticed that under Tuning/acceleration RPM vs Amount, all my RPM banks read 100 and the amount banks 0. Why is that? what does that map represent?

can you see in the logs the TPSacc amount?

[AVP]

yes. they are all 0.0.....hmmmm

why is that???


Also rechecked older logs as well. All of them are 0.0 !!!! so basically im running all this time without ANY accel amount? why?

[gunni]

Cause it has not been tuned.

[AVP]

what do you mean?

Under Settings/ acceleration enrichment i have values:

4-20-40-60 for dv/dt

and for acceleration amount:

0.0/0.6/1.2/2.4

why arent these values written on the datalog?

[gunni]

Cause you need to tune the RPM amounts as well.

[AVP]

what values should be there then? on the rpm amounts?

i must say that i have never read that in all searches i have done about accel.enrichment!

[AVP]

do those scales actually work on 1.1.44?