Audi RS2

[AVP]

and besides,as i already mentioned the EGT readings i look at,at the moment are not the ones VEMS sees,but the ones that the independed EGT sensor sees,which has been used for the original map of the car

[AVP]

has anyone tried using a voltage stabilizer,same as those people use when having big ICE systems in their cars?

i am getting a voltage drop from 14V to about 12V from when the engine is just working (14V) to engine + all electrical equipm. on (12V) and it is that time that the PID control is not working that well.If i could get that voltage adjusted a bit better,maybe vems would have less trouble controlling idle.

[rob@vems.co.uk]

Are you sure that its the ICV thats being effected and not that the dwell and the injector voltage compensations that are incorrect?

Have you pulled your idle timing back to the ~9deg thats needed?

Don't get too hung up on perfect idle at this stage, it is a very tricky thing to get right, how is the low and part load mapping going?

[AVP]

well i tried 2 sets of spark tables to compare. The one that had reduced advance,brought the EGTs even higher and quicker. The other one was slightly better.

i redid the spark table to try and make it more accurate for the VEMS,and im going out in a little while.


As for the ISV valve, the thing is that i do want to make the idle acceptable and though im amazed that i have all configuration now pretty much found for the cold + warm start and operation, when it comes to alter those to compensate for increased load, things begin to mess up and it cant be done right.Dwell time is 2.5ms

It appears that there may be a voltage drop substantial to VEMS to make it very difficult to control the idle.I tried the 9-10Deg option and almost got something that is acceptable again on normal load, but once it got more needy(AC on/lights/fogs etc) it got even worse.

it may be a matter of configuration really, BUT i do fear that in the end, it will need more than 1 configuration to get things right.

IS there a setting in VEMS that can 'not see' the voltage drop due to load so that it can react similarly without changing settings that already work nicely?

[AVP]

i noticed today after the tests that the battery voltage that VEMS sees can alter with lightish load up to 1V. Now i know that with more current, voltage draw may be more,but i didnt test that today.

As far as mapping is concerned i noticed that i need to advance the map a bit more to be able to get to the temps i need.When i use lamda=1 on the low revs, temps go higher the less advance i give.

How easy is it to get knock on low revs? (up to 2900 really where no boost is coming in anyway)?

[gunni]

You would have to run vera lean and extreme advance to get knock at low rpm´s

[AVP]

this is my latest spark table.. how does that seem to you? i know that every engine is different,but..



here is the lamda im going to try with it

[AVP]

I have mixed feelings today after the runs.

1) Idle control: Have managed to find various setups that would work on normal load circomstances,but not that well under load and voltage drop. Still needs optimizing

2) Spark table is pretty much ok on the areas that i manage to look at.By OK i mean that if i decrease the timing, EGTs travel upwards when lamda=1.If increase the spark to a point,things are ok,(but still EGT higher than what motronic is capable of doing).Any increase more than that,and you can 'feel' that the engine is not running right.So not tampering with timing anymore.

3)I tried making the mixture richer than what it is to be able to have nicer EGTs on cruising speeds, and it worked a little,but the engine was actually happier when lamda reached a value of 0.95 or something!!! Now that is not right...

4) I noticed that on different TPS values,the car had EGT jumps quite high, SO i thought of altering the MAT enrichment table a bit to add a bit more fuel when TPS is more depressed. That does help matters a bit, but it goes completelly against the gas ideal law.As my car does long hours of testing and stationary tests, MAT can go up to 50 or 70C and on those areas and low TPS dips im supposed to substract fuel, not add to it! However engine is running hotter when i dont do that,so? what else to do?

Something that really bugs me is the fact that with TPS od 5-10% the lamda goes really lean!!! why is that?

Overall from 1300-3000rpm and 30-110kPa, motronic is able to keep EGTs at about 100-120C less than what VEMS can do.

And im wondering.. if those areas on most(if not all) maps are tuned in a way that should be stoic,since you are aiming for economy at cruise, how is it possible to have even for lamda=1 that big of a difference,when spark table is close to as good as it gets?

Also from the motronic fuel table i have(which is not lamda orientated,(rather than numeric,could be ms of injection or just a value) i can clearly see that all those areas of rev range and load(maf values) are using the lowest values from the rest of the table.Hence they should be at least lamda=1 if not less!!!!

Could this be a lamda calibration error? could this be something else?

[AVP]

also, what does the 'engine' column stand for in the datalog?

[rob@vems.co.uk]

Ideal gas law does not take the dynamics of an engine into account, you start to use fuel to cool the cylinder slightly.

No matter what the calibration error is, lambda 1 is always lambda 1, the calibration accuracy dictates the quality of the reading either side of lambda 1.

Are you talking about the mixture going lean when you hold the throttle at 5% to 10% opening, or are you talking about during the acceleration event?

[AVP]

when it is steady at 6-8TPS for example and steady revs, it is always much leaner.. like 1.05 or 1.08 or something. Not an acceleration event

[rob@vems.co.uk]

Are you sure that its not the fuel map at that kpa?

[peter_jensen]

As I can see you are using 1.1.44 I due not think that’s a good idea because it’s not a released version use 1.1.27 instead.

A lot of code is been made the last year but not everything is working, as it should and it can affect some bad behavior in the Vems.

I use 1.1.44 in my s2 but having great trouble controlling the fuel also EGO correction seams wired.

Always use a released version   


 Peter

[AVP]

peter, you may be right in the end about this. Marc told me that he had been testing the 1.1.44 version and was happy with it so that is why we decided to go for it.

i changed my VE table on the bottom line just to try it once more.

i also managed to get through to the terminal to see the wideband calibration. Wideband was not vrey dirty,and read 20.5 in atmosphere. I didnt get it back to 20.9 because if because of the dirt it is unable to see the correct concentration of O2 in the air, i took it back to 20.7 to 20.8 instead.

Peter, do you think my EGT problems could be because of that?

I dont know if i should go back to 1.1.27 or just wait for the 1.1.50 version...

[peter_jensen]

Hmm I also talked to Marcell and he told me to use 1.1.27 only use experimental firmware if you need the new functions badly so if marc have told you to use 1.1.44 that will surprise me.

Also it’s wary important that you have the (h0) in order so you are firing the injectors in the correct order ore you will have a bad idle.

I think you should use 1.1.27 and when one of the new firmware is released you could upgrade then.


Tnx peter