Important read for alky tuners!!!!!!

I will try and keep a long story short.

When I originally had my car tuned on a smallish alky system (which I think is perfect, and kinda wished I hadn't sold) the AFR specified in the Primary fuel table was in the 12s. This ended up with a nice solid 11.7:1 AFR. ..........GOOD!

I then tuned my car with a larger alky system and played around with anywhere from 400-750 cc/min of alky. I found that I was calling for 14.7:1 in some spots, and I still couldn't get indicated AFR above 12:1.

In retrospect I wish I had done the math, really simple really. I was led to believe from other tuners (sorry Edmundu) that even calling for 14.7:1 AFR might not be enough, and one may have to skew the MAF scale to pull enough fuel to hit the desired AFR.

Turns out there is this table in our ECU (the second one), FWIW I couldn't find it anywhere in ST-AD.

http://i248.photobucket.com/albums/gg194/littlebluegt/minenrichment.jpg

It is caller Primary Open Loop AFR Lean Limit. If you look at it you will see that above a throttle plate opening angle of 69% the ECU will only allow things to run so lean, above 87% 13.02:1 is the limit.

So you can call for 14:1, but if the throttle is at 100%, your ECU will only be targeting 13.02:1!!!!!!

This could cause damage if the car is driven at around 60% throttle opening, and one tuned the car trying to pull fuel from higher load cells to acheive the desired AFR. I tried logging my car, and it seemed that my target boost at that throttle opening angle was low enough to cause any FBKC.

My findings:

If your MAF is scaled pretty close, and you inject 500 cc/min of alky and your target actual (read form WB02) AFR is around 12:1, you will not get it. If you adjust the above table so that the last two cells are higher then 13.02:1 (maybe 13.5-14:1) then you will have enough headroom to hit your targets. If you are injecting 450cc/min or less, or if the upper end of your MAF is off a bit, then this may not affect you.

Your findings might be slightly different, but you should at least be aware of this table.

As usual I didn't figure this out on my own, Merchgod from Romraider helped me out, good guys over there!

Of course tuning is easy, and supposedly I spend too much time on it, and I should just be happy and drive my car. Well, I am glad I figured this out!

I would put this in the tuning forum, but..............

Great find LBGT:)!

I'm not a know it all, nor perfect. So I can readily admit I missed this one.....And I thought I had looked through the tables.

This jives with my observations that at lower alky flow(350-450 cc/min) I could easily get the afr I wanted with just fuel table offsets. But with higher amounts, I was actually using the MAF "clamping" method. Which is simply telling the ECU their is less air coming in, and hence it pulls fuel, allowing you to get to your desired fuel afr.

BUT, I don't see where the skewing of higher load cells is going to affect 60% throttle area. IF you drive at 60% and tune for it, there isn't a problem. But if you wonder off into cells you hadn't previously tuned for then I could see that happening.

In any event, whether you use the "clamping" or adjust this table, the outcome is still the same. You are aiming to pull fuel to a desired afr. If you use an alky map w/o alky you will still have a problem.

BUT, I don't see where the skewing of

Not sure what you are saying.

Skewing will work, but better to adjust the table and allow for a leaner AFR at WOT.

I am sure you could inject 1000 cc/min and still hit a 12:1 AFR.

^^^ I was responding to your "60% throttle driving could be an issue..."

At that throttle, you wouldn't be landing on any high load cells, at least not on my setup.

The benefit of adjusting this table allows one to have target afr closer to actual. But the end result is the same. I agree that having to use less offsets and "little white lies" is better for the ecu, so that in some situations it doesn't come back to bite you in the a$$.

LBGT, let me see if I understand that table correctly? If your enrichment table targets leaner than 13.02 at throttle of 87% or greater, then it will default to this table?

If your enrichment is leaner then 13.02 then yes it will only target 13.02.

Thank you again, LBGT. This explains something that has been running me in circles for a long time.

When I first began my meth tune all went well and predictable There was a direct correlation between fuel tables and logged AFRs via WBO2. But the more I added timing and pulled fuel, then increased my meth injection percentage to 'cover' it, however, that direct correlation faded.

So I quit asking for more. There is enough already. I don't want or need any more power.

That's a lie. In fact I may even be pissed at you LBGT. Here I had gotten to a good stopping point and you come along and dangle yet another carrot for me to chase. Now I'll have to go back to pushing my tune further, sticking my poor LGT's toes out over the edge.

And why isn't this thread posted in our Tuning Forum!??

Oh, I forget, Tide doesn't want us to have one.....

Someone say tuning forum???

I think it is better that we discuss food and drink in a LGT forum.

where can one find this in romraider? What section is it under?

It's in the "Fuel" folder about 5 lines down.

LBGT, you back from France yet?

It's in the "Fuel" folder about 5 lines down.

 

LBGT, you back from France yet?

Yep.

Sick of driving an 80 hp Fiat.

Wait...

Are you taking about food or drink? I did see Alky in the title :lol:

Wait...

Are you taking about food or drink? I did see Alky in the title :lol:

A little over 13 drinks of alky for every snack item, or something like that.

The benefit of adjusting this table allows one to have target afr closer to actual. But the end result is the same. I agree that having to use less offsets and "little white lies" is better for the ecu, so that in some situations it doesn't come back to bite you in the a$$.

Sick of driving an 80 hp Fiat.

;1910422']Nothing wrong with that if it had 180 lb-ft torque (diesel).

No, gas powered.

It was about a 2 min steep uphill drive out of our villa that we rented, I tried once shifting into second from about 5500 rpm, but it couldn't do it in 2nd, had to shift back down to first.

Once I was driving slightly uphill about 10k under the speed limit (130 km/hr) and a realized I had the car at WOT for over 5 mins. Nobody in the car could tell.

;1910421']In other words' date=' it's better to understand and control how the ECU actually makes decisions rather than to simply twiddle knobs (i.e. "lying") in order to obtain desired results?[/quote']

 

Of course:) It started with fiddling with carb jets, progressed to piggyback ecu's, to where we are now with the oem ecu. Caveman to modern man....You had to have started somewhere.

 

We still do not have all the tables involved in tuning, but we have enough to make some decent power with very good drivability...

where can one find this in romraider? What section is it under?

It's in the "Fuel" folder about 5 lines down.

 

LBGT, you back from France yet?

Although I have looked at every item in the "Fuel" folder I have no such table. User Level set at 4

My CAL ID:A2WC500C, ; 05 Subaru Legacy GT, AT

Anyone care to comment?

Although I have looked at every item in the "Fuel" folder I have no such table. User Level set at 4

 

My CAL ID:A2WC500C, ; 05 Subaru Legacy GT, AT

 

Anyone care to comment?

I can't get my damn laptop to print screen however, I just loaded a A2WC500C rom and it is there. Fuel>Minimum Primary Open Loop Enrichment (Throttle). It is about 5th from the top.

Although I have looked at every item in the "Fuel" folder I have no such table. User Level set at 4

 

My CAL ID:A2WC500C, ; 05 Subaru Legacy GT, AT

 

Anyone care to comment?

E-mail me your rom.

Although I have looked at every item in the "Fuel" folder I have no such table. User Level set at 4

 

My CAL ID:A2WC500C, ; 05 Subaru Legacy GT, AT

 

Anyone care to comment?

Likely you are using Enginuity 0.4.1b. It had not been updated for over year, so the ECU and logger definitions were over year old. The ECU/logger defs were being updated independently of Enginuity and users would update their defs manually for 0.4.1b. RomRaider version 0.5.0b was just released, however, and it comes with the latest defs. So, all you need to do is go to the romraider site and dl and install it and you will be good to go.

Likely you are using Enginuity 0.4.1b. It had not been updated for over year, so the ECU and logger definitions were over year old. The ECU/logger defs were being updated independently of Enginuity and users would update their defs manually for 0.4.1b. RomRaider version 0.5.0b was just released, however, and it comes with the latest defs. So, all you need to do is go to the romraider site and dl and install it and you will be good to go.

Thank you. And thanks to LBGT and Infamous, too. I'll be doing this today.

Whew! I was worried.

Edit:

Well, I got and installed the latest Ecuflash and RomRaider and now all is well.