Quote Originally Posted by 5cottymac View Post
So been trying to fool this thing all day with no notable progress.

I warmed up engine to operating temp and made sure tstat was open at 200 degrees. I revved and held engine at 2k RPM to ensure IAC was completely closed...
What would make you think the IAC was completely closed like this? Seriously I'd like to know...

More RPM and IAC opens more, it's called the throttle follower.

Here's the Procedure for setting IAC... but I don't use it anymore as I have found that adjusting IAC when motor is warmed up and driven for a data log that at end of log I idle in gear a minute and in neutral for a minute. Look at IAC counts! Keep them under 20... if they are 40 then turn throttle stop screw (has nothing to do with idlae RPM setting) in 1/4 turn to let more air over throttle blades and less through IAC. When done you need to turn engine off for a minute and restart so PCM calculates TPS % to 0, it does this every time. This is why having your foot on gas pedal when turning key on is a bad thing.

2. IAC reset/min idle speed- This sets the throttle plate on the throttle body to a specific rpm. It should be set to 100-125 RPM below idle commanded in bin file. At ALDL connector you need to put a jumper between pins A and B of the connector. These are pins A9 (what/blk) and A12 (blk/wht) on the ECM. This puts the ECM into ALDL mode. Turn the key on (not start) and the IAC should drive completely closed. You will normally hear a buzzing from the IAC. If you have the TunerPro running up and running on your laptop, or a Scan Tool you should see the IAC went from 145 to 0. Now unplug the IAC connector. Turn the key off. Remove jumper. Start motor. If the idle is too low you may have to keep it running. On the front drivers side of the throttle body is the adjustment screw. It will probably be behind a silver plug. If so just use a drill bit slowly to drill a hole, not to deep as to damage the torx screw behind it, just enough to use a punch to grab it and remove it. Then use a #20 torx bit to adjust the idle speed to at least 100 rpm less then your warm idle speed in bin. If 600 then set to 500 rpm. You are looking for the lowest consistent idle your motor will do. When set, turn off motor and reconnect the IAC. I try to keep the IAC count to at least 10-20 with the motor warm and idling. Higher number are OK but more air pushing gas past throttle blades on TBI engines is better!
For your data how about checking what Pin the ALDL data is coming through on? Some cables can read both Pins but others need a specific pin. Code 12 and what your CEL is doing is a good thing!

160 baud on pin E of ALDL port and 97427 is 8192 baud on pin M of ALDL port.
You need 8192 Baud Pin M and then correct ADX... I forget what bin your using? $0E or $0D?

Do you have a stock Memcal to put in and try it instead of the Howell?

Set timing to 4*, clear codes. Check timing, where is it at when warmed up?