Idle Spark Settling Below Commanded

Hi guys,

I'm trying to find the missing link as to why my idle spark works its way down so low. I feel like I have touched all related tables, but must be missing something.

I have tuned the idle airflow and ETC idle angle tables as well. My thought was maybe because of more than anticipated air, it is using spark to keep RPM on target, but I have observed the low spark value even with slight positive idle air trim.


https://forum.hptuners.com/attachmen...8&d=1541423347


https://forum.hptuners.com/attachmen...9&d=1541423356


Attachment 84618


Attachment 84619

Quote:

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Originally Posted by CCS86

Hi guys,

I'm trying to find the missing link as to why my idle spark works its way down so low. I feel like I have touched all related tables, but must be missing something.

I have tuned the idle airflow and ETC idle angle tables as well. My thought was maybe because of more than anticipated air, it is using spark to keep RPM on target, but I have observed the low spark value even with slight positive idle air trim.

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What's your desired idle rpm? Is it reaching it? -10 ft. lbs seems it's trying to decelerate..

I would think more air (and subsequently more fuel) into the engine would make the spark lower and vice versa.

Idle setpoint is 800 rpm.

I tried a couple tests today.

First I reduced the idle airflow table by 25%.

Next, on top of the first change, I reduced the ETC Idle Throttle Angle table by 20%.

Neither test netted a change in the idle spark at all. Interestingly, the short term idle trim value didn't change either, and it stayed at +/- 0.02. I definitely would have expected a change here. If the idle air trim isn't based on the idle air table, then what?

Here is my MP0 torque table compared to a stock GT table. I have big reductions in torque in the idle area, which I would think would elevate spark to compensate:

Attachment 84626

All experience I have is with the 18 5.0's, & GT500 tunes.

On GT500, the air tables do nothing, to test, put the max values in, see what happens. Lotsa tables in GT500 tune do nothing, one is even said to be airflow, but if you enter say 6, the throttle will open 6 degrees.

Try to get idle good by adjusting torque tables, that's all that would help mine any at all. Idle spark is only used when idle is not controlled by torque.

Quote:

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Originally Posted by CCS86

I tried a couple tests today.

First I reduced the idle airflow table by 25%.

Next, on top of the first change, I reduced the ETC Idle Throttle Angle table by 20%.

Neither test netted a change in the idle spark at all. Interestingly, the short term idle trim value didn't change either, and it stayed at +/- 0.02. I definitely would have expected a change here. If the idle air trim isn't based on the idle air table, then what?

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I think RPM Ctrl mode is it's own little system unaffected by many things in the tune. If you were in dashpot mode I bet you would have saw a difference.

What does your inverse table look like? What is engine brake torque and torque request showing in this screen shot?

Quote:

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Originally Posted by Thatwhite5.0

What does your inverse table look like? What is engine brake torque and torque request showing in this screen shot?

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Attachment 84654



Attachment 84653

There's a switch for if it uses torque or airflow tables for idle control if you're talking 11-14 cars. You can disable torque based and use airflow. If I remember right you have to lower the airflow amount to enable dashpot also. I haven't messed with it for a while.

Are you talking about the TQ based decel switch? I don't see anything specific to idle control in my calibration (2012 GT FPDX)

Unsolved mystery!

I still cannot seem to make any change on the idle spark.

Here is a log and screenshots of the transition from "target N" return to idle (which I can affect), and the switch over to "idle feedback" spark source (which seems impervious to changes).

This screenshot is continuous data, but I copied the "after" data to the right side of the screen for comparison:

Attachment 90713

You can see that after making the switch (both spark and torque sources simultaneously), it trades a bunch of spark advance, for a larger ETC opening angle.


There has to be a missing link here. Either a table labeled something unintuitive, or missing from editor?

I agree in thinking RPM control is it's own system and there are no tables defined to edit it. Heck on mine I'm even unable to put it in dashpot only mode. What makes me think it's missing is when I use a married SCT to datalog there are a ton of pids that don't show up with HPT. Things like effective area, map, idle torque (which differs from any torque values shown in the VCM scanner). I'm in no way an expert in Ford though and still trying to understand them myself so take what I say with a grain of salt. Maybe someone who uses both systems can chime in.

I flashed 15 revisions this morning, testing one or two parameters at a time and didn't have any luck in raising the idle spark advance, once settled into "driver demand / idle feedback"... not where I wanted it anyway.

I tested:

• TQ Inverse values
• TQ values
• Idle Control Enable RPM Error
• Spark Only Torque Ratio for idle control and driver demand
• Spark Torque Ratio Limit for idle control and driver demand
• Driver demand torque
• ETC Idle Throttle Angle Expected vs. Airmass
• Idle Airflow (Drive) vs. Desired Idle RPM

Finally, I wondered if it was intentionally keeping spark low to keep the cats hotter. I edited "Exhaust Flange Temperature" and multiplied values by 1.5 in the idle range. This seems to have brought spark up from ~6.5* to ~10*. Maybe there is something to it. Further increases netted no further spark advance.



Does anyone have access to SCT advantage, to compare available idle related against scanner (spark, torque, etc)? If we can find specific tables that are missing, we have a decent shot of HPT adding them.

Here is what the latest beta has in my FPDX strategy:

Attachment 90727


I definitely don't have any "idle" specific torque tables or settings. Those could be important too.

There is talk of new parameters headed to S197 strategies, so now is probably a good time to request things. Hopefully someone with SCT access doesn't mind digging around for the greater good!

Not sure if you have these tables or not. I saw one file were the combustion pressure limit was restricting spark towards idle. It was near the edge of a load point so as the load changed slightly at idle it was causing idle spark to jump around. Side note, after seeing that I used those tables to lock my spark down at idle. (Making my idle spark advance, limit, and minimum all the same) Adjusting my predictive and effective throttle tables helped stabilize my idle (not 100 percent perfect but a ton better) Also was able to adjust idle areas of MAF better since timing wasn't jumping plus or minus 10 degrees and was staying stable.

Don't know if any of this will help but figured I'd share.

Attachment 90737

Quote:

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Originally Posted by momotunes

Not sure if you have these tables or not. I saw one file were the combustion pressure limit was restricting spark towards idle. It was near the edge of a load point so as the load changed slightly at idle it was causing idle spark to jump around. Side note, after seeing that I used those tables to lock my spark down at idle. (Making my idle spark advance, limit, and minimum all the same) Adjusting my predictive and effective throttle tables helped stabilize my idle (not 100 percent perfect but a ton better) Also was able to adjust idle areas of MAF better since timing wasn't jumping plus or minus 10 degrees and was staying stable.

Don't know if any of this will help but figured I'd share.

Attachment 90737

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Thanks momotunes

I'm good on 3 of those, but I don't have table 32270. I'll ask support about it.

I have something close: ECM] 44616 - Spark Cylinder Pressure Limit vs. RPM vs. Load:

Here are my related table values, but I am still getting 8 - 10* advance at idle:



Attachment 90738

Spark Cylinder Pressure Limit vs. RPM vs. Load is probably the same. I forgot to mention mines a 3V 5.4. Do you mind if I can see you file. Having no experience I probably won't be of help but I always like a puzzle lol.

Here you go:

Thank you. I didn't get a chance to look at it today. I had the bright idea of making a fan shroud and had some problems mounting it. I'll look tomorrow.