Cooldown enrichment

[mr_g]

This thingy is something that every stock ECU has... So stock ECU doesn't have EGT. But it calculates EGT based on lab tests... So, you boost a few times and after about 20 or 30s of hard boost it brings boost down and fuels up engine... So you are like idling after that, but it still fuels engine for about 20 or 30 seconds... That thing is cool down enrichment...

Could we get this option in VEMS because it's really needed... Why? Because we like to cruise on 1.05 lambda... And after a hard boost you would normally let the things cool down with nice little cruise.. But in fact it wouldn't cool anything on 1.05...

So, this guys with turbos and forged everything doesn't have this problem, but normal mortals like me, has one... On VEMS, I already fried 3rd piston and a few piston rings, so I'd like to avoid that in the future...

[gunni]

I don´t know of anybody having that problem from that.
As soon as you start cruising running low intake temps and charge the EGT´s start falling rapidly.

Do you have any surten info that the bad rings and pistons are caused by this and not something else?

[rob@vems.co.uk]

When the engine is running hard its dumping power into the coolant.  When you lift off theres a lot of energy stored in the coolant so you're going to want to run a little richer to cool the engine down.

Thats taken care of in the coolant enrichment setup in the newer firmware.

[mr_g]

Nice... If that's the case... Alto, EGT based enrichment would be nice....

Well, I did fry the 3rd piston... We don't know for sure the reason... I have a few guesses...

That day I did swap the injectors (300cc to 630cc) and just change injector setting in basic config... I did check EGO on all rpms at it looked fine (alto it's hard to look on those numbers when you are trying to control the beast on boost)...

I had a few problem before with a fuel pump setup... When fuel level in tank was below 1/4, on hard cornering and acceleration, I was left without fuel... But that didn't make any problems with motronic, just the power lost for a second... I was doing speed jump from 100km/h to 200km/h with just 1/4 gasoline in the tank, so maybe this was the reason for less fuel...

Maybe the engine was on it's end, so 0.7bar just pushed it to the death..

The boost was pretty mild, just 0.7bar (motronic stock is 0.6bar with 0.9bar overboost), but it's was constant in all the gear to 7000rpm... Motronic is knocking boost down in 5th and 6th gear to 0.4bar, and it is knocking power down above 5500rpm... VEMS was really hard torquing all the way to 7000rpm... C20LET was suppose to deal with 1.3bar on stock internals... Not just 0.7bar... But it seems that Motronic is hardly retarding the ignition above 6000rpm to prevent engine faster wearout...

The car was pulling really hard... Much harder then motronic on 0.6bar, and it fried the piston... But in those 2 days, Damn, I have smoked my friend with new S3 with miltech exhaust... So it was worth it... :lol:

[Denmark]

I think it´s "bad" mapping that lets you destroy pistons, eighter to much advance or to lean, or both.

I run lambda 1.06 at cruising upto 4500rpm,  and have run several runs at the Ring, without trooble, that´s on the chokolate internals on a early EJ20, running 1.3bar boost


/Skassa

[mr_g]

How does engine smoke in the eghaust change wbo2 readings?

Well, it's hard to map ve on the road, but spark was pretty retarded...

[rob@vems.co.uk]

Smoke will effect the lambda reading its more than likely going to read rich.

[Denmark]

And the spark needs to be advanced to run cooler on cruise, more = cooler egt.

To some degree



/Skassa

[gunni]

Advanced timing will also put more stress on the cooling system.
as heat is not going out the exhaust but into the cooling system.

[GintsK]

Advanced timing will also put more stress on the cooling system.
as heat is not going out the exhaust but into the cooling system.

IMHO it goes more in mechanical energy.

[GintsK]

But yes. We need some control using EGT. With EGT enrichment (direct) it should be possible to tune little leaner an get more power until EGT goes high in hard 5th gear pull.

Offt. Can someone can tell how to different piston damage caused from detonation and lean?

[rob@vems.co.uk]

I have found (with the AlphaN idle controller enrichment) that if we write up a specification of EXACTLY what we want, that it gets developed.

[GintsK]

2D lookup table?
Like this:

EGT................870..900..930...960....1000
Enrichment%....0.....3.....5.......7.......10