No hiway mode fuel in $32 and $32B bins, only hiway mode spark. Hiway mode fueling was introduced in the 89 $6E masked bins.

 

OK....Now that we beat that w/o a conclusion (for me), the OP shows a scan with 27 as the spark degree. I assume that would be his target spark at idle. I'd consider that "normal" and reasonable for what TPiS would pick as the timing for idle. Stock idle (spark) isn't much different for the AYPY or ARAP bins. (ARAP has an idle spark of 25 at 800 rpms. I would expect TPiS to pick 800(ish) as the idle speed for a performance cam.)

Some performance tuners would recommend a couple degrees more advance for a performance cam. I don't see that as being 8-degree higher than necessary. 27-deg is also lower than the 40-deg (full-advance) complaint that began this thread. In fact, I don't see his timing as even being off!

Note though, that his IAC stepper motor was WAY too high. It showed neither he (nor TPiS) has performed the necessary idle timing screw set procedure.

When the OP is sitting there with the motor idling at 6-deg BTDC (and the ESC wire is disconnected), I assume the IAC is non operational. When he plugs the wire in, he says it shoots up above 40-deg and idles very fast. It probably sees it's not idling at the commanded 800rpms and over-reacts. If he makes it up in the 1000rpm range -- before it settles down, he'll see it hit full-advance (timing) before settling back down to 800rpms and 27-deg advance.

My thought is the IAC is THE issue. He needs to adjust his idle screw to open the TB blades until IAC drops around 50-steps. Then, I think he'll see the timing and idle performed in a more reasonable manner (while performing normal timing maintenance).

An IAC reading of 71 is WAY off where it's supposed to be. Absolutely, no question about that.

 

Greggpenn, previous post with hiway fuel/spark...all greek to me, lol. But you are correct again with base idle and IAC. I went back, started from basics and found base idle at 350-400 rpm's, bouncing around barely running, but surprisingly ran. I adjusted to just below 500 rpm, I think base is supposed to be 450rpm. I then went and readjusted TPS back down to 0.54 volts. Then tried to reset IAC. Seems like timing and idle is more correct. Idle will jump to 1300 rpm, then come back down to 800-900rpm, and timing is around 28-30 advanced. Seems way better, but after a minute or two, light comes on and engine runs terrible, can hardly idle, stumbles and will not accelerate, just like when I drove it home. Even though light comes on, I cannot get a hard code from computer. I use a Innova 3140, no codes, at one time when I connected A&B at diagnostic connector I had a code 33 flash. But could never get it back. So, for now I will wait until Tuesday to get it back on Snap On scanner to see if any codes can be retrieved, and also check where the IAT is at after adjusting base idle. Again, do apprecate yours and everyones time, efforts and smarts on all this...

 

Interesting, you can't get a code.

Your logic about the rpm setting is wrong (for a modified car) except to set the base timing. With the TPS set at .54V, disconnect the brown wire, and turn your dizzy until 6-deg BTDC. (Use your idle screw until you can get a stable idle. On mine, it was closer to 600rpms. (But don't worry, you're still not done with that idle screw!!!)

Re-connect the brown wire.

Reconnecting the brown wire will get the ECM back in the game...and cause a surge. That's because your IAC is still not set correctly. Really your TB is not set correctly for idle. (I can tell because your feedback on the prior page shows a 71 stepper-motor count.) Since I use TunerPro, I monitor the IAC counts with an ALDL connection. I turned the idle screw (opening the TB blades) until the IAC counts drop to 15 (w/o fans running). With the fan running, make 20 steps your target. The engine needs to be at running temp to perform the IAC adjustment!!!

I suspect you will find another 2-3 turns will be required to lower IAC counts near 15.. By opening your idle-stop (and providing a normal pathway for idle air to enter your modified motor), the IAC will close by itself. That's because the ECM has direct control of that device and uses it to maintain commanded idle speed. When you open the TB blades, the IAC drops because the ECM no longer "sees" the need to provide more air and raise your rpms -- to the level commanded by your custom BIN file. (FYI: You can only see commanded idle speed by viewing the programmed BIN file.)

Once you've set the idle screw to get a 15 step IAC count, reset the TPS to .54V. Because your idle screw has now been set for correct idle operation, resetting your TPS, will provide the ECM with base idle throttle-positioning.

You may not need to, but I'd remove power and reconnect it so your ECM can start fresh (and learn the new positions) based on your new positioning.

You may be getting a code from your MAF if/when your idle goes below it's intended target. If it tries to sit down and idle below 800ish, sometimes the ECM will throw a "MAF - low signal" code. Even though there is no real error. Codes are cleared when the battery is unplugged. Hopefully, you'll stop getting this code when you've got your TB set correctly.


FWIW...The IAC is a stepper motor device that allows air to bypass the circular throttle blades and make it into the plenum. The more steps, the more it's open to "bypass" air into the plenum. With the IAC, the ECM can adjust air intake at idle to control base idle, fast idle, and anti-stall function...all in one unit.