going lean during burnout

[mustangless]

I looked at this for a while and don't see a dumb mistake.

When doing a burnout, my lambse will be 11.44 and my afr will be low 11s. Then my afr will hit 20+ and my lambse will go to 16.1. After a short time, it will go back to normal. But then it will do it again.


My maf curve is rich, but I have been working on that. You can see by the entire log, my afr is in the low 11s.

This is the same on both of my logs.

[cgrey8]

I looked at the log and I see what you are seeing around ET 37.75429, but I don't know CBAZA well enough to guess as to why the EEC might do this. TPS, Load, and MAF look high enough to indicate OL, but the datalog shows CL as TRUE which is terribly confusing. However even if you had gone CL, it doesn't make sense that the LAMBSEs would jump from 11s to 16s then back to 11s.

I don't even have a good guess as to what's causing this.

[mustangless]

Maybe somebody that knows cbaza better will chime in. This seems to happen at my peak rpm. I have my rev limiter set at 5800 on 5700 off. I wonder if that is causing this.

Edit.
I am about certain that is whats happening. I looked at another log where I know it was the rev limiter. Same 20+ afr and 16.1 lambse. That sure does not sound safe. I was told it is though.

[cgrey8]

The WB will detect this as running lean. But rev limiters don't just pull fuel across the board. First stage rev limiters randomly misfire injectors (averaging to about every other injector). So the cylinders that do fire, fire with their full compliment of fuel and thus they don't run lean. And obviously the cylinders that don't get an injector fire, don't get any fuel to burn. This is why the rev limiters are safe for the engine. However from the WB's standpoint, it see's a massive amount of oxygen and reports the condition as it see's it...lean. Now 2nd stage rev limiters will pull all fuel. So if pulling 1/2 the fuel doesn't get the RPMs down, pulling all of the fuel most definitely will.

What's disturbing though is the 16 LAMBSE. The GUFx strats don't do that. But it is quite possible the newer strats do? But for what purpose, I have no clue because it sure makes things look like the cylinders that did fire, fired lean and were commanded to do so.

[boss96]

It seems to me that if you are reaching a low enough load at some point during the burnout and going back to CL that the eec will command a very lean lambse to try and swing the a/f back toward 14.7. I also would not trust the CL/OL indicators in Calcon, I would just take note of where you have set your rpm/load to go OL and see if that is the load you are at when seeing the "lean" problem you described.
Bob

[mustangless]

I had adjusted my Air - Load Limit Open Loop vs RPM, so maybe I did it wrong. I had stock

1638 77.00
5400 82.00
4800 82.00
4200 85.00
0 85.00
0 85.00
0 85.00

But I changed it to
1638 0.00
5000 0.00
3300 60.00
3000 50.00
2500 60.00
2000 85.00
0 85.00

I thought this means that it would go OL at 5k at any load. Did I do that wrong?

edit: I looked at my other log where my shift point was above the rev-limit. After it hits the limit and load drops from 120 to 98 the lambse goes to 16.1

I attached my tune too.

[bender460]

I have to throw this out. This might be a good situation for a race track only tune that is forced open loop.

[mustangless]

Isn't Cl = 1 mean OL? My log shows that it stays there throughout the burnout. Then it goes cl =0 until I take off again.

[Cougar5.0]

The WB will detect this as running lean. But rev limiters don't just pull fuel across the board. First stage rev limiters randomly misfire injectors (averaging to about every other injector). So the cylinders that do fire, fire with their full compliment of fuel and thus they don't run lean. And obviously the cylinders that don't get an injector fire, don't get any fuel to burn. This is why the rev limiters are safe for the engine. However from the WB's standpoint, it see's a massive amount of oxygen and reports the condition as it see's it...lean. Now 2nd stage rev limiters will pull all fuel. So if pulling 1/2 the fuel doesn't get the RPMs down, pulling all of the fuel most definitely will.

What's disturbing though is the 16 LAMBSE. The GUFx strats don't do that. But it is quite possible the newer strats do? But for what purpose, I have no clue because it sure makes things look like the cylinders that did fire, fired lean and were commanded to do so.

In GUFB the rev limiter does just pull fuel across the board - see re-post of the description and logic below. Alternate firing of injectors is only a SPEED LIMITER, not a rev limiter. It appears that CBAZA is a full-cut limiter too, though there is a mention of using Stage 2 (alternate injector firing) in a "mid gear stage 2 rev limit" in CRAI8, though there's no way to tell if CBAZA used this and the parameters are not visible in CBAZA if it is used.

[cgrey8]

Damnit, I always forget that. You are right. Speed limiters have a 2 stage random misfiring of injectors. But rev limiters are all-or-nothing. That's like the 2nd time I've gotten those two backwards.

[2Shaker]

Isn't Cl = 1 mean OL? My log shows that it stays there throughout the burnout. Then it goes cl =0 until I take off again.

Yes, "1" means it is in OL. Dumb question maybe, but are you sure there is enough fuel being supplied? The injector duty cycle is only at around 50% so I'm thinking about pumps, fuel rails and fuel line.