AFR troubleshooting issues (SC 3.8)

[2000Falcon]

Well, after 3 summers and only 25000 KM on the new motor, my goal of getting a good tune in the car has been haulted by some sort of gremlin that has used up all of my local resources and a lot of my money, not to mention every last ounce of my patience and soul.

I am honestly BEGGING for help here as i'm fresh out of ideas.

We had made a lot of progress, the AFR was locking in at the commanded 11.5 and the KR was way down. Suddenly one day between tunes, I squeezed into the throttle and the car goes rich, 10.0:1 (and my gauge only reads down to 10, so it may have been far less). On another WOT stab, the AFR locked in at 12.7. Another time at 12.2. Other times the AFR will lock in at 11.3-11.7 or so. I will post scans below to give you an idea of what i'm talking about. I will also post the tunes themselves below. It is my understanding that there was nothing changed in the tunes to cause such an odd AFR abnormality.

The bin files started at "A", and the latest one is "M". The means of tuning has been via the "Open Loop MAF tuning" as seen here:

http://www.hptuners.com/forum/showth...&referrerid=73

The second gear Open Loop pull with Tune "D" was the best the AFR ever was (locked in at 11.5). See Scan "D1" below. At present I have tune "M" loaded, however I went back to tune "D" a couple of months ago and was able to induce the same AFR issues.

The scans "M-3 var" and "AFR Issues" will give you a good idea of how the AFR is all over the map. Also, the idle conditions are odd at times, and it's almost like the car will hicup and lean out to 19:1, then stay around 17-18:1 for a while. I did get a P0171 code once this week when this happened when I was idleing in gear and rolling. The AFR was 20:1 at idle.

See below for the list of actions and troubleshooting up to this point:

- Removed air filter to check for restriction. None found.
- Reverted to tune "D", same AFR issues experienced.
- Checked for vacum leaks, all tight.
- Cleaned MAF. No change.
- Replaced MAF. No change.
- Checked Fuel pressue. Idle=41, Part throttle=51-53, WOT=58 psi. All ok.
- Replaced MAP sensor. No change
- Cleaned IAC. No change.
- Replaced IAC. No change.
- Unplugged EGR valve. No change.
- Commanded EGR valve open and closed via Tech 2. Confirmed operating.
- Replaced O2 sensor with new. No change.
- Confirmed TPS voltage and throttle position. All ok.
- Attempted to swap PCM's, however the only spare I have is locked.
- Drove the car with the Tech 2 connected and observed values as follows:

=== @ WOT with AFR of 11.5:1: MAF = 290 g/s (approx)

=== Induced 10.7:1 AFR (3rd gear, approx 65-70% throttle) then increased to WOT AFR 11.0:1: MAF 180 at start, then to 220 g/s at WOT (AFR of 11.0:1).

=== WOT lean condition (12.2:1): MAF 220-230 g/s.

=== WOT, MAF 7.2 V at 90 KPA (roughly, based on memory).

Based on the above info and the attached files, I am praying that someone can lead me in a better direction. My time home is so limited, that i've had this new motor in the car 3 summers now, and it's still working like *#^%, and i'm really ready to burn it (the whole car).

Anything at all would be appreciated. Thanks so much in advance.

Ross