UrS4 2.2T Avant project

[Thuppu]

Ok, so the fuel/IAT correction will be always in use... I remember last time on dyno the tuner was astonished that suddenly the engine started to go lean in the upper end. We was thinking about the fuel temps, tank and pumps was really hot. But it may be this setting that started to take over..? This is factory setting, I havn't touched it because I was thinking it's just for engine start(heat soak adjusment). And now I have had lambda correction up to the redline so it hasn't gone lean even at 100C IAT.

I think I will set the correction to zero and take few dyno runns with the lambda off and see how it behaves.

[Kieron20V]

You want to be adding more fuel with higher iat to help cool the charge and protect the engine, not sure you have that table set up correctly. I'd be a bit more cautious than disabling it and going for a thrash.

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[diesel des]

As iat increases the actual corrected mass flow of air through the engine drops so required less fuel. But you are correct the mixture is more likely to ping or detonate and a richer mix helps reduce that. Would take some experiments and Thomas's test method seems good to me.

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[rst]

Thomas, what lambda are you running on WOT with E85?

[Thuppu]

Haha, lol, 563hp/763Nm @5090rpm and the room was filled with white smoke. The actual run did go to maybe 6500-7000rpm, don't know why it wasn't calculated higher..? No mechanical sound from the engine, it just started to blow smoke from the breather. Maybe head gasket or a piston..? The coolant looked normal so it may be a piston.

The brake on the dyno was incredibly hard, and I'm not sure if they did know 100% how to use it..? It's a brand new MAHA MSR500.

[Thuppu]

Full WOT has been lambda 0,77-0.80.

[A80Avant]

I don't trust maha dynos. They always increase the brake on high powered cars and they produce huge torque with cap power figures. So I don't know how hard that pushes the engine as well.

[Error404]

Thomas with the after start enrichment you can tune out the problems with lean hot start due to heat soak in the fuel rail.
You can add fuel to reduce chances of knock with high IAT but you would need to carefully find where your knock limit might be as IATs rise. Then you can add some additional fuel if necessary above your AFR target. I guess on E85 you have more safety margin

[Thuppu]

I don't trust maha dynos. They always increase the brake on high powered cars and they produce huge torque with cap power figures. So I don't know how hard that pushes the engine as well.

Yea, the run feeled like it took forever, I was thinking that the engine will not survive and that was just what happend. You look at the boost gauge, 3 bar has been there for a while, how much longer will it hold... PUFF!!!

Nothing close to real life stress on the engine. Another negative thing with such a hard brake was that when the rpm's rised so slow some resonaces and vibrations did like multiply and feeled really hard, that caused a trigger erreor a couple of times, what havn't happend on street or track.

[diesel des]

So you have a burnt or broken piston now? Have you done a compression test?

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[rst]

Damn bad news.

As for lambda, i and some of my friends are running lambda ~0.72. The power you make is the same, but engine will run cooler. EGT will likely drop 50 or more degrees.

[V6quattro]

Damn bad news.

As for lambda, i and some of my friends are running lambda ~0.72. The power you make is the same, but engine will run cooler. EGT will likely drop 50 or more degrees.

But fuel economy!!!!

[Error404]

Is there any need to run that rich? Adding that much fuel to cool crazy IATs seems counter productive, combat the cause of the problem

[diesel des]

Alcohol seems to tolerate a much richer mixture without droping power.

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[Thuppu]

But then there is also a risk of flushing the bores.