Whacked Commanded AFR?

[N0DIH]

Look at my commanded AFR. What gives? I have been unable to get this righted. Sorry, don't have WB hooked up at the moment (need bung installed).

Anyone have any insight?

This is primarily off the GM stock tune. I did try to richen it some, but no dice.... I don't think I can enough if Commanded AFR is what whacked out.

As long as I don't go in PE Mode, I don't get kR issues, but as you can see what AFR is when I DO go into PE mode.....

Mods? Gutted air box only.

[SSpdDmon]

Vehicle? Tune? Post more please...

[N0DIH]

00 Park Ave Ultra, L67 (Supercharged 3800), not supported tune wise in EFILive, but scan tool works great.

NOW I can't get the Commanded AFR PID back, it is showing as not supported, yet last night it WAS supported. This isn't the first time I have got PID's that aren't "supported", Adaptive Spark is another that used to come and go until I just deselected it. Makes me wonder what is up.

Vehicle? Tune? Post more please...

So now I question the data, is it REALLY reading the Commanded AFR? Just for giggles I went massively rich to see if it would run right, it does not. So I suspect the values ready are not valid.

The issue. KR is seen at the time I enter PE Mode. STOCK TUNE. When I got the car it did NOT do this, it does now, the ONLY changes are TR6 plugs (didn't help the issue which is why I installed them, just left them in) and a gutted airbox. when it is below 70C, KR isn't allowed (stock) and I did notice one day I could hear it, it is somewhat of a much higher frequency knock, engine was probably 30-40C at the time.

The common denominator. PE Mode. If I move it up to 80% throttle, KR happens there, if I move to 100%, KR happens there. If I move to 30%, KR happens there. But yet if I move to 100%, power is down on heavy throttle, if I move it down, power is much much better, yet I get KR. So it IS enriching fuel, but yet it is like it gets a momentary lean time.

The most pronounced time is cruise @ 45 mph/70kph and give it 70% throttle, it will have KR coming out the wazzo. I have seen as high as 15 degrees in warmer weather, in 30-35F inlet air, I have seen it stay "down" to 7-8 degrees.

Dumping excess fuel via MAF tuning or via PE mode fuel ratio/EQ hasn't helped either. Dropping timing way down enough to quench it, makes it run VERY poor.

Attached is my tune in a .bin format, but EFILive of course doesn't support it. HPT might, but not sure if it can open a .bin. TC2 can, Jet DST can for sure.

[swingtan]

That log file looks quite weird. for example....

• The voltage levels for the 2 O2 sensors is way out. Bank 1 appears normal and is cycling well. Bank 2 however appears to be running extremely lean for most of the time and is not cycling at all.
• Going along with the O2 sensors, the LTFT's are off as well. Most of the time LTFT for bank 2 are running at -80%.
• Then we see that the injector duty cycle for both banks is very close, in fact they are exactly the same.
• TPS % drops to "0" at times but the engine keeps running. Normally I['d expect the engine to stall at 0% throttle.

Given the vehicle is running fairly well, I'd say that in fact ScanTool is not compatible, at least not completely. I'd say you are getting invalid data for at least some of the PID's you are trying to read, like...

1. : Commanded AFR
2. : HO2S21V
3. : TP%

I may be wrong of course, but it would certainly explain the funny data.

Simon

[N0DIH]

Bank 2 is post cat (V6 FWD.... only has 2 sensors, pre and post cat)

Curious, why would it stall at 0% TPS? That is what happens when you back of the gas on any car. Thinking of PW maybe?

[swingtan]

Ahh, OK. I see now. That will explain the differences.

I still think there may be an incompatibility with the 2 systems though. The AFR line is inverted from what I would expect, so there may be a calculation that is needed to "correct" the graph. Given it looks inverted, you may be reading an EQ ratio of sorts.

Simon

[N0DIH]

Looking at my O2's, I am thinking that I am looking at a bad cat, rear O2 does hang rich (absence of excess O2) more often than it should so it is quite possibly the cat.

Would a bad cat cause KR issues like this at this point? Would it be "backing up" into the combustion chamber and causing it to lean out?

[MICK]

Tom,

I think the Lads are at Sema so you might have to wait till they finish up there before you can get some serious answers. The command pid does look a little strange. Most of the important stuff is there though.

For now see if you can get that wideband hooked up and that will give you actual AFR which is more important for now. Drop the LTFT #2 as the data from the rear O2 is lazy.

One good thing is that you could work off your LTFT #1 as that looks to be on the money. You could build a custom map to suite the VE table of TC and plot your VE correction that way for now. I find that most of the VE tables in TC are transposed to that of EFIlive, so this is one plus. I see that the unit values in your VE table are VE% so this will make it a little easier then working with engineering units.

The best option for correction is to use Bens which is commanded AFR vs actual AFR and with Paul's help maybe you might be able to get this going.

One thing I did notice is that you have a few pids selected which brings your channel count up to 29. See if you can keep this under 24 or so and you will pick up better data in your logs.

Cheers

Mick

[swingtan]

looking at the O2 voltages, anything under say 0.45 is lean and anything over say 0.45 is rich. The cat will alter the O2 levels a bit but if anything, I'd say it looks lean not rich.

I had a play with the data from your log file and can get a normal looking AFR graph if I treat the log data at an EQ ratio, assume stoic as 14.63 and then assume in the data supplied that stoic = 5.51. then doing a conversion gives me a normal looking AFR graph. I've attached the image but remember, this is a calculation and may not be correct at all. the WB should help a fair bit.

Simon

edit: I should also mention that it appears you are running load based fueling. this would also explain why the commanded AFR's follow the MAP so closely. You may need to work on these tables at the same time as the PE tables.

[N0DIH]

Here is the efi file from my drive in today.... Ignore the first bit in OL, I was messing around before I let it go into CL, and just after a fill up, so LTFT's are way rich after a fillup and it sucks the tank pressure down.

And today the Commanded AFR isn't working. Paul and Ross didn't understand why on that sort of thing.

Maybe I will datalog with AutoTap tonight and see what I get on that one.