Link ECU tuning Log:

January 1997:  I had the EARLY FM ECU installed - it had a few quirks, to say the least.  Most annoying was stalling when returning to idle with the A/C on.

January 1998: Bill and Link upgraded me to the new ECU board with the throttle position sensor wired in... better, but it had some new quirks of its own (wouldn't run at all with the default fuel map...  has a really annoying "lurch" when throttle closes... A/C better, but still crazy at idle)

January 1999: Got the new software... better still, but those quirks are still present, especially the AC performance at idle, the compressor switches off and on like every 3 or 4 seconds, sending the idle swinging, and eventually stalling if you let it.  Has Bob (at Link) put ANY hysterisis in the compressor control?  Also, I've threatened a few times to bypass the throttle position sensor, I'll probably do it this time - I really think it makes the ECU perform worse.  At least it fires up and runs with the default map.

Here's a quick rundown of my setup this evening:

  1. Gain access to ECU.
  2. New chip in - old chip on standby, just incase something horrible happened in the mail.
  3. Key on - don't crank it yet!
  4. Check what the settings look like
  5. Switch to Turbo Mapping
  6. RELOAD (maps were way crazy as delivered....)
  7. Crank it (fingers crossed) it fires and idles decently
  8. Adjust Idle up to 1150 (was 850, I stall less at 1150)
  9. Adjust Clamp up to just above whatever it was reading (maybe 39)
  10. Lambda ON
  11. Go to the Zone Fuel reading, watch it tune itself in zone 110
  12. Adjust zones 100, 105, 200, 205 and 210 to match final result in 110
  13. Adjust zone 100, 105, 110, 200, 205, 210 advance to 6 (from the Dlr Alt FM Owner's page - better emissions, smoother idle, or what this is for, I'm not sure.)
  14. Adjust RPM limit to 7300 (I'm a wuss, so shoot me)
  15. STORE (!!!)
  16. Cruise around neighborhood, all seems drivable, at least, reassemble floor panel
  17. Switch from Keypad to datalogger
  18. Go out for some full range RPM runs
  19. First couple of runs show me lean all over the place
  20. Switch back to keypad, bump up master fuel from 31 to 33 (more runs) then to 35
  21. Readjust idle as above (STORE!), back to datalogger
  22. Couple of more runs, show better overall tune, with a few holes
  23. Back to keypad, adjust fuel up in those zones (STORE!)
The following is TBD (after Superbowl Sunday):

Repeat runs with Lambda ON 'till all looks right with the world, then turn Lambda OFF and do it again, manually adjusting fuel zones 'till as close to "target" as possible in all zones.  When everything looks nice & smooth on the O2 sensor curves with Lambda OFF (STORE!), and switch Lambda back ON.

If you're still lusting for more power, I'd let my tank run near empty, then put in about two gallons each of premium and "mid grade", tuning for this fuel mix should provide some safety margin for day to day driving.  Basically, go out & do it again, this time, bumping up timing in each zone 'till you get a half a ping, then bump it back one degree.  This is very slow work (you really can't datalog for it unless you have a 1.8 with a knock sensor, so you'll probably need lots of open road to do 4th or 5th gear runs - so you spend enough time in a given zone to connect it to the pings you hear.), as Shiv said, "tuning for the last 5% is 95% of the work."  After you're done, fill with premium and you should be back to a decent saftey margin.

By the way, I do "runs" for rows 3, 4, and 5 - 0psi, 6psi and 12psi of boost.  Tuning row 2 is more of a cruising thing.  Also, as Sean mentioned, the Superbowl traffic is hell, so I'm sticking close to home and doing these in 2nd gear- you've basically gotta have a datalogger to make sense of 2nd gear runs.

The "Screen shots" show where I was at just after bumping master fuel to 35.  The big ramp on shot 1 is RPM climbing during a roughly 0psi run.  O2 sensor readings are the fat line up top.  You can see lean conditions at the start of the run, and another hole later on.

Shot 2 shows a "cursor" on the later hole, and numeric analysis of that point at the bottom of the screen: Zone 355, Fine Zone 56 (dead center, more or less), Throttle Open (255), and O2 sensor shows 0 (I think the rest are INJ, ADV, DEG and BAT, but not really sure, I surely wasn't looking at them.)

Shot 3 shows line by line data for that same general time.  You can see that zone 355 is seriously lean, O2 drops to 0, just in that zone.  The default map had 350 at 41, 355 at 39 and 360 at 41 - bumping 355 to 41 seems to have solved that particular hole.

Shot 4 is from the drive back to the house, you can see repeated twice there the same lean spots in zones 310 and 315.  They needed some "enrichment" too.

Kills Bugs Fast