I'm too Rich!! --part II

[tgeers]

Thanks to everyone that responded to my post yesterday. It was very helpful. Thanks to you, this has been a big and rather pleasant learning curve for me.

I think I have approached the tuning backwards. It was my plan to work with the VE table and then finish with the two PE tables. But if I understand your comments correctly, all of you are saying set the PE tables first and then get the VE table to cause my AFR to match the PE. After looking at JoeCar's logged data itappears that he was trying to get his AFR to match his command fuel values.

Let me know please if this is what I should be trying to do.

If so, I would like to set my AFR to be a little lean on the low RPM side for the better fuel economy, and around 12.5 or 13. at peak torque.
Does this sound like the right approach?

Finally, when working with the VE table, it's my understanding that no values should exceed 100. and if they do, the PCM will just round them off to 100.
Is that a correct notion? And if that is correct, what does it mean when you need to raise those numbers above 100 to keep from being too lean?

Thanks again. I know this is elementary to most of you, but it's all new to me.

Tony

[ringram]

You can report ve table in various units. If you look at the min and max values you will see what the pcm can handle. For % you can go as high as 500%

When dialing in the table you usually disable PE, DFCO, CAT, fuel trims plus some other bits so you can eliminate any extra things that mess up your logging.

If you run OS3 you can command leaner at idle/low map and richer for WOT no problem when tuning ve, though often people will recommend using a flat value to further refine the accuracy.

I think you should follow the autotune document as it has the "right" approach.

Your goals for AFR sound fine though I used to run 16:1 at low map, then pretty much the values you mention for WOT.

[joecar]

Yes, do the auto ve tune procedure first; this will allow you to see the PE AFR you set in the PE vs RPM table show up on the wideband AFR;

this is how I got actual AFR to match commanded AFR, makes life much easier, and also my LTFT's (when I occassionally use closed loop) are in the range -1.0 to 0.0.

Forget about VE table having units of % because it's not really a VE table, it is an airmass table; with the auto ve tune procedure you don't have to think about the units of the VE table; after your VE table is dialed in, adjust the OLFA and PE tables for the richness/leaness you want; the OLFA is a little tricky because it is not indexed by RPM.

When working on the OLFA and PE tables, be careful to understand the units you are using (AFR, EQ, Lambda) since it is easy to get them confused; I use EQ exclusively, and I do the conversion to AFR on a calculator only if I really have to (I should make myself a little table as some people have done).

Basically, if you make sure that the IFR and VE tables are correct and true, then the rest of your tuning will be easier and engine seems to respond better.

[tgeers]

Hi,
I've made this post part III because I haven't replied to part II in a couple of days I am hoping RingRam and JoeCar will see my response here. I am very grateful to everyone who has been helping me. I found RingRam's write up on a tuning proceedure for new guys, really helped. Thank you.

JoeCar comments were very helpful too. After reading your comments I discovered this little tidbit you might not be aware of. It was certainly new to me. The question was raised as to how do the PE modifier (B3618) and command fuel in Open Loop (3605) interact with eachother and the fueling of the motor. I tried an experiment. I first zeroed out all of the PE modifier and ran with just the command fuel. The car ran fine. Then I zeroed out both and the car would not start. Then I zeroed out the command fuel only and the car would not start. Therefore my conclusion was that the command fuel must be primary and the PE modifier, well I still don't know what it does.

I went racing yesterday and had the PE modifier zeroed out and was able to get a 12.5 AFR at WOT.

If there is some error in my thinking about this, please let me know.

Thanks
Tony

[joecar]

Tony

B3618 is enabled when TPS vs RPM meets/exceeds B3616; when B3618 is enabled, the PCM uses whichever of B3605 and B3618 is the richer, otherwise it uses B3605; (...this is while running open loop...).

in your case you got no start because the B3605 was too rich (AFR) or too lean (EQ).

Your actual (assuming what you said) AFR was 12.5 at WOT; B3618 allows you to go richer at peak TQ and to go leaner at peak HP, my understanding is you want this, especially if you go racing;

if your VE table has been dialed in (using Auto VE Tune procedure) then the actual AFR equals the commanded AFR; this is desirable because you can then get your actual AFR or EQ correct the first time you set it.

Also... PE vs RPM is further modified by PE vs ECT B3617 and PE vs IAT B3641.

Regards
Joe

[joecar]

The idea is to set your cruising AFR in the OLFA table, and to set your torque/power AFR in the PE vs RPM table.

[tgeers]

Joecar,
Now that makes sense to me. My learning curve is beginning to look more like my torgue curve now.

Thanks again.
Tony