UrS4 2.2T Avant project

[A80Avant]

Ok. I'll put it on tonight and post

[A80Avant]

without looking into fine details here is what i got from the log power wise, but as i say it may be an overestimation etc etc.

what i notice is that you probably dont use VEMS for boost control at all, do you? do you have an aftermarket boost controller?

Also your lamda EGO loop seems to be on all the time, but you are not allowing for any corrections to be done as the limits are set to zero. Nonetheless VEMS was able to increase the fuelling need for the run to 108% towards the end as your VE map was requesting way lower fuel than needed. (safety feature). Also is the timing of 15deg flat something of a basic setting on which you plan to work on?

Was this run on pump gas or E85? i suspect on pump for you to ask for lamda 0.78

Maybe the above could in part explain the power curve.

[Thuppu]

Supricely identical curve on the upper end. What is a good limit for the EGO control, seems to be set up to 8500rpm's? 3000-3500rpm's? Have missed the whole EGO-setup.

So what is the safety feature for the VE? The tuner was adjusting the VE- and ignition maps on the dyno, always comparing the result to the previous run. In my eyes it seem'd the it couldn't take more timing. The result in the upper end on the dyno curve stayed almost identical from 450hp level up to the 600hp level. Everything the tuner tried had no effect there, less timing it got worse, more timing it got worse and so on. Thats why I suspect some problems with the harware, the IM comes first in mind.




Already checked the catalytic converter and made a de-cat pipe. It seem'd to be ok, but at least there isn't anything in the exhaust that is limiting the flow...

[A80Avant]

Looking at the log the amount of fueling is not that much and the ecu was adding fuel to get it to the desired 0.78 lamda.
Ego correction if you want the ecu to adjust on all rpm and conditions you put the rpms in and then set the limits to at least +/-5 so that the ecu would do something on the offsets of mixture. In your case the ecu did it out of safety feature which was added to latest firmwares which means that your lamda table is followed to some extent regardless of the tuner so that you don't get a meltdown

[Thuppu]

Ok, so the ecu have add fuel to reach the lambda(EGO) target that was accidently set too high up. And yes, I'm using e85, so it's quite strange that it's so prone to timing..?

[A80Avant]

if you are using E85 then why are you having a lamda requested at 0.78? That's why it's knocking as for E85 that is way too lean!

When the VE on the log goes above 100 it's adding fuel. Yours was 107 to 108. If you had requested lamda 0.70 (i don't remember which is ideal for E85 ) it would have gone to 115 or more trying to reach that proper fueling level.

Also the log shows that the map was already too lean and the ecu was adding fuel to keep it at 0.78 lamda.

So the VE table needs to have higher numbers put in when on boost.

[Billman]

Lambda is the same either for Gasoline or E85. The AFR changes.

[V6quattro]

I also running lambda around 0.79 on E85.

[Thuppu]

Hmm, lean? I'm not sure about that. With Motronic I dynoed 612hp(@7100rpm) with lambda 0.81.

Edit.

Ooh, now I see what you mean. You are thinking of these:



It's just easier to use normal gasoline AFR. Lambda is measuring oxygen of the exhaust gases and shows it as lambda values that is converted to AFR values. So normal gasoline values works with E85 as well.

[Billman]

Log seems fine in general. Check the boost control system you are using and maybe lean it out a bit as it goes down to 0.76. maybe you lose a bit of power because of this.
You also have that boost cut that you should sort out.

Check the rest of mechanical stuff that can cause late spool like:

Boost leak, cam timing.

[A80Avant]

Yes correct about the lamda. Somehow I thought that needed to be lower in vems. See you get that if you never use e85

[rst]

You can add a lot of timing there Thomas. You timing map is more like for gasoline than E85. I have 26 degrees advance timing with 2.5bar and E90. Also i allways use lambda on WOT 0.75 and for me it works very well. Keeps egt down.
Little table


Friend of mine uses E100 with 3.5bar boost and lambda 0.70-0.72.
So dont be afraid of richer afr.

Thomas have you checked if your timing is correct with stroboscope?

[Thuppu]

have you checked if your timing is correct with stroboscope?

Yes, we checked that.

[Thuppu]

You can add a lot of timing there Thomas. You timing map is more like for gasoline than E85. I have 26 degrees advance timing with 2.5bar and E90. Also i allways use lambda on WOT 0.75 and for me it works very well. Keeps egt down.

Risto, so you use EGO correction all way up to the limiter? How much is you correction? Doesn't it made the AFR to live/change a bit? Well, propably that won't do any harm..?

Even that my setup had the EGO correction activated to 8500rpm, it seems that it was pressure limited to 160kpa, so it had dropped off on high boost.

[rst]

I only use EGO correction on cruise (up to 0.5bar and 3500rpm). I allways turn off all correctiond when tuning. You can set EGO lean/rich valus to 0 when tuning and after tuning VE i usually set them 10 for rich and 5 for lean.
If the lambda for example goes bad, i dont want the ecu to change anything at WOT.
We started with lambda 0.80 in the beginning of the dyno on my car and changed it cradually to 0.72. Nothing changed except for lower egt, the power remained the same. EGT dropped about 50-100 degrees if i remember correctly. It was 3 years ago.
From my experience go as rich as possible as long the ethanol ignites, then you are good to go.
Also dont use cold spark plugs with ethanol. For example i am using NGK BKR7E ones and change them every 5000km with the oil.