[ChrisArnold]

I have a 5.0 1991 Mustang LX with the A9L & am tuning with licensed BE on a Quarterhorse. Basic combo: GT40X heads/GT40 tubular intake/E-cam, 75mm Bullet Pro-M 'calibrated' to my 30 lbs injectors. Transmission is a T56 from an '03 Cobra. So, I had to remove the neutral safety switch (NSS).

I followed Leech's tuning videos, setting all injector parameters, inputting Pro-M's MAF function, setting base idle scalars to 800 rpm, adjusting relevant tables to account for that, measuring & cross-referencing MAF voltage to set ISC Duty cycle to around 35%, and I believe I'm pretty close with idle. It's nice and stable for the most part. There's a couple spots where I still need to work through surging... Anyways,

I noticed that the commanded spark never budges from 20*. That's consistent with the 0.648 Idle spark multiplier and Idle - Spark vs. RPM setting of 31*. I have validated that the EEC is not having any issue commanding timing outside of idle. Commanded timing immediately changes with blip of the throttle, and while otherwise driving the car. This issue is only happening at idle.

My theory is that since I have no NSS, the computer has rejected using either idle-spark table. Here's what BE's help file says about these tables.

"FN841D - ISC Spark Multiplier versus RPM Error in Drive (in gear - manual with neutral switch)."
"FN841N - ISC Spark Multiplier versus RPM Error in Neutral."

My questions:
1. Am I on the right path with this line of thinking?
2. Is there anything else that would cause static idle timing? For example, I read something about dashpot mode, but need to read more to see if static timing is symptom of being in it...
3. If this is my issue, can I wire something up to send a signal to restore Idle-spark control from at least one of these tables? i.e. can I send a signal that will cause the A9L to believe it is either always in neutral or always in gear without disrupting other tuning parameters?

[Paulie]

Being stuck in dashpot mode can cause static spark at idle. Set TRLOAD to 0 and see if that fixes the issue.

[JuiceSC]

+1 on TRLOAD=0

However, you mentioned some idle surge is present at times. This statement and the fact that there is no timing movement at idle tells me that you still need to work on idle.

What is KAMRF at idle, fully warmed up?

[ChrisArnold]

Guys, that worked. Thanks very much. Timing at idle has been restored.

TRLOAD -
0 = manual, no clutch or gear switches, forced neutral state
1 = manual, no clutch or gear switches
2 = manual, one clutch or gear switch
3 = manual, both clutch and gear switches
4 = auto, non electronic, neutral drive switch
5 = auto, non electronic, neutral pressure switch
6 = auto, electronic, PRNDL sensor

That TRLOAD suggestion aligns with having no clutch or gear switches & forces it into a neutral state. TRLOAD=2 sets it as one clutch or gear switch. I do have a clutch switch, but I've read that it's part of the NSS circuit on foxes. Trying '2' out also resulted in getting spark adjustments at idle. Is there a reason to prefer one setting over the other? If I'm forcing a neutral state, will have have any 2nd order impacts anywhere else in the tune?

Regarding the idle surging, trying things out today resulted in a very stable idle with no surging. Yesterday, I noticed exactly what you were trying to point out. KAMs were adding 10%. So, I made some more tweaks to the MAF xfer down there, as well as the ISC (reduced and spread the gain multiplier) and a couple scalars. So, hopefully, I'm in the clear on smoothing the idle, now.