Warm up table vs charge temp table

[Wroom]

I stumbled onto something when trying to perfect the AF to lambda 1 on light load.
I got a very stable lambda 1 calibrated. But what happens is that when the engine is around 70 degrees it get a bit lean. It vill show AF somewhere between 15-15.8 instead of 14.7. When the car is warmed up the AF is perfect. That is, even if it is 10 degrees or 30 degrees out there.

Then i come to think about the warm up table ends at 70 degrees. Why not letting the warm up table continue all the way up?

Well, the autotune will be inhibited as long as the warm up multiplier is not 1.0 so it might not be a very good idea to do this.

So the question is how to best perfect the AF in the transition from end of warm up and to a fulla warmed up engine? Should i compensate for this in the charge temp table instead?

How would you do this?

Warm up table:
http://www.mrm-racing.se/forum/attachment.php?attachmentid=125&d=1211990563

Charge temp table:
http://www.mrm-racing.se/forum/attachment.php?attachmentid=126&d=1211990563

[Chris]

What do you consider as fully warmed up temperature ? 85-88 celcios ?


Chris

[Wroom]

Yes, exactly about there in temperature. Say 87 degrees celsius as nominal work temperature at normal loads.

I'll elaborate on the idea a bit. Think it is an interesting discussion on implementing fuel compensation.

Isn't it so that if one compensate in the charge temp table so the engine will maintain a slightly richer AF when coolant temperature rise from the nominal 87 degrees to, say, 100 degrees celsius. Then at the same time it will lean out at a lower temperature than nominal work temperature.

So if one would compensate for the 70-87 degrees transitional warm up region in the charge temp table, then one will also get a leanout at higher coolant temperatures than nominal.

So if one wants to maintain ideal lambda in open loop all the way up to nominal working temperature, and still to have a slight enrichment when the engine is under very high load, then one will need to make compensations in the warm up table. Either by elongating the warm up curve all the way up to nominal working temperature, or by
adding enrichment in the table above nominal working temperature. Or by making corrections in an Aux fuel comp table.

If one makes a compensation in the warm up table, then autotune will be inhibited when the warm up multiplier is not 1.000 because of the settings in the PC warnings/log menu. If one changes the limits to allow more than 1.000 before warning, then one will effectively introduce an uncertainty in the autotune, so that if one tunes at a high load, then the AF will adapt to that load, and that will offset the fuel compensation within this uncertainty.

But the same is true for having a compensation in the charge temp table. If the engine is tuned at 87 degrees, then everything works as planned with enrichment above that temperature. But if the engine is tuned at, say 92 degrees, then much of the enrichment expected at temperatures above 87 degrees will be taken away, and instead a leanout at temperatures below 92 degrees compared to expected AF will be seen.

So as i can see it, adding fuel at higher than nominal temperatures in either the warm up table or the charge temp table must be done after tuning the engine. And changing the charge temp table after tuning the engine is not a good way of adding a compensation for high temperatures.
Using the Aux fuel comp tables work similar to the warm up table, but using an Aux fuel table is a good means of implementing an enrichment on overtemp, since it is a separate table. Aux Fuel Comp table 1 can also be enabled/disabled in its entirety.

[turboe36]

Are the axis' not editable in the warmup table?

[Wroom]

Are the axis' not editable in the warmup table?
Yes, axis is editable.

[Ian]

If you want to put in additional Coolant dependant fuel without inhibiting the Autotune can you use one of the Menu M2 - Fuel trim - Aux Fuel Comp tables or do they also inhibit the Autotune?

You say you mixture problem occurs when the engine is not warmed up even if the running temperature is a cooler temperature than normal. Can this mean that the issue is perhaps when the engine oil temperature is not stabilised in its relationship with the coolant temperature? Buzzard and I were having a similar discussion about this in relation to another application today.

[turboe36]

I'm sorry maybe I'm not following correctly but--

Why not just make 0 load 1.025 and 100 load 1.012 @ 70 deg, then add an axis of 85 deg and use 1.0 and 1.0?

[Wroom]

I'm sorry maybe I'm not following correctly but--

Why not just make 0 load 1.025 and 100 load 1.012 @ 70 deg, then add an axis of 85 deg and use 1.0 and 1.0?
Yes. As long as the coolant temp does never go below 85 degrees during tuning that seems to be a good solution. But the temperature can go as low as 80 degrees under some circumstances.

One could though set the warm up table to end enrichment at 85 degrees, and edit it down below 80 degrees temporarily when tuning, to avoid the inhibit.

[Wroom]

If you want to put in additional Coolant dependant fuel without inhibiting the Autotune can you use one of the Menu M2 - Fuel trim - Aux Fuel Comp tables or do they also inhibit the Autotune?
I checked, and they work the same as i remember it. Maybe i should check again?

You say you mixture problem occurs when the engine is not warmed up even if the running temperature is a cooler temperature than normal. Can this mean that the issue is perhaps when the engine oil temperature is not stabilised in its relationship with the coolant temperature? Buzzard and I were having a similar discussion about this in relation to another application today.
Yes, the problem is at the end of the warm up, when it nears the normal operating temperature.

The oil temperature is probably affecting this. The engine has oil jets under the pistons.