[jungspike]

Why is my AFR at idle 20?

First let me say that the SW chip solved most of my problems. Power is much better and AFR is 13.0 at WOT, but…

My idle AFR is 20.0, why? My idle switch is broken (waiting for a new one from Germany), so I have been driving around without one-- idles around 2000 RPMS with AFR at 14.7. I decided to see how the car will idle when I get the new switch: Since I have a MAF, I cannot set the CO levels. I jumpered the Idle switch to tell the DME the engine is at idle. I then set base idle to 880 (car hot, O2 sensor connected, B & C jumpered). Car idled fine… maybe a little rough, but more importantly the AFR was at 20.0!!! After I disconnected Jumpers B & C and took paper clip out of idle switch (idle circuit not engaged, but throttle closed), RPMS go to 2,000-ish and AFR to 15.0—basically back to where I was. I took her for a drive and AFR was fine at WOT and cruising. What would cause idle AFR of 20.0? Intermittent Idle Control Valve? I don’t think I have any more vacuum leaks (see my list of tests that have run below).

Not sure if it is related, but when I was looking for dead cylinders, I disconnected each injector and listened for an RPM drop. Sometimes a cylinder caused a significant RPM drop, other times it was very subtle (same cylinder). Also, some cylinders dropped more than others. Could this be related to my high idle AFR?

My plan:
1. Check fuel pressure (Verify Fuel Damper operation & Residual pressure)
2. Pull the spark plugs and look for indications of rich/lean
a. Visually check for spark on each cylinder
3. Install new Idle Switch (waiting for parts) and re-set base idle
b. Check ignition advance
4. Check electrical system voltage
5. New spark plug wires (current set has about 10K miles on them)
6. Replace all injectors
7. Re-dyno and update SW chip

Things that I already checked:
1. New fuel pump, filter & regulator
2. Checked Idle Switch (failed—waiting for parts)
3. Checked Idle Control Valve (Ohms & cleaned)
4. Adjusted WOT switch (it was out of adjustment & not clicking). After adjusting, I checked operation with voltage & click
5. Disconnected brown wire by DME
6. Confirmed Fuel Quality Switch is in Position 1
7. Found & repaired vacuum leaks
8. Checked “static” timing
9. Swapped DME Relay
10. Checked fuel injectors with noid light and listening with screw driver—all checked good
11. Checked for dead cylinders by disconnecting each injector--very inconsistent changes, why???
12. Confirmed gas tank is breathing
13. Ensured throttle plate is adjusted (0.04mm when idle and full open when full throttle)
14. Looked for sparks jumping in engine at night (none)
15. New rotor
16. Check Altitude Switch--good
17. Check Cylinder Temperature Sensor-good
18. Swapped DME and Autothority MAF/Hotwire for stock flapper box and another DME— AFR much better (12.5-ish at 5,000 RPMs): Conclusion problem is with chip or hotwire
19. New SW chip, cleaned & calibrated (set to 2.2 kOhms) hotwire. Reinstalled MAF. Full throttle is now around 13.0 and 14.7 while cruising