Turbo Foxbody Idle Help

AwxyMoron

Member
Apr 3, 2021
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Hello,
Not entirely sure if this is where I should be posting but, I recently put in the Holley Terminator X Foxbody kit along with a Holley dual sync distributor in my 88' Turbo Foxbody. Everything has been running great so far but the idle. With closed loop, IAC and spark adjustment the car idles okay cold and warm, but at startup it surges badly and every once in it will jump about 200rpms then settle back down. In open loop with no IAC or spark adjustment, the idle is very bad, usually from 600-1300rpms. The setup is a TFS Stage 1 cam, tfs sb intake with 75mm throttle body, 61mm turbo, Ford Racing Z heads and 9:1 compression and my target idle has been low 800's(which I should be able to hit with the current setup?) however even when aiming for 1000rpm idle, the issues stay.

I'm pretty new to tuning but I think I've been doing okay up until trying to get this car to idle where I want it to.

So far I have:
-Set the IAC to Ford PWM at 315 frequency in Holley software
-Set the idle screw in a variety of positions from completely closed to 1000rpm with no IAC
-Completely cleaned the throttle body and IAC
-Messed around with the Startup and IAC ramp down settings a lot, (I tried the Fixbody videos settings as well)
-Tried to create my own 1D IAC table(based off the Fixbody video)
-Tried idle timings ranging from 10-22 degrees
-Targeted AFR's from 13.5-14.5
-Slightly lowered Startup enrichment

I have some photos of the current and my best tune so far(idle timing has not been smoothed yet), I can also send the file to anyone who wants to take a look at it. Any help would be greatly appreciated, thank you guys!
Spark Table 5May21'.png Target AFR 5May21'.png Base Fuel Table 5May21'.png Learn Table 5May21'.png IAC settings 5May21'.png
 
Last edited:
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a91what

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Mod Dude
Apr 6, 2011
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Hello,
Not entirely sure if this is where I should be posting but, I recently put in the Holley Terminator X Foxbody kit along with a Holley dual sync distributor in my 88' Turbo Foxbody. Everything has been running great so far but the idle. With closed loop, IAC and spark adjustment the car idles okay cold and warm, but at startup it surges badly and every once in it will jump about 200rpms then settle back down. In open loop with no IAC or spark adjustment, the idle is very bad, usually from 600-1300rpms. The setup is a TFS Stage 1 cam, tfs sb intake with 75mm throttle body, 61mm turbo, Ford Racing Z heads and 9:1 compression and my target idle has been low 800's(which I should be able to hit with the current setup?) however even when aiming for 1000rpm idle, the issues stay.

I'm pretty new to tuning but I think I've been doing okay up until trying to get this car to idle where I want it to.

So far I have:
-Set the IAC to Ford PWM at 315 frequency in Holley software
-Set the idle screw in a variety of positions from completely closed to 1000rpm with no IAC
-Completely cleaned the throttle body and IAC
-Messed around with the Startup and IAC ramp down settings a lot, (I tried the Fixbody videos settings as well)
-Tried to create my own 1D IAC table(based off the Fixbody video)
-Tried idle timings ranging from 10-22 degrees
-Targeted AFR's from 13.5-14.5
-Slightly lowered Startup enrichment

I have some photos of the current and my best tune so far(idle timing has not been smoothed yet), I can also send the file to anyone who wants to take a look at it. Any help would be greatly appreciated, thank you guys!
Spark Table 5May21'.png'.png Target AFR 5May21'.png'.png Base Fuel Table 5May21'.png'.png Learn Table 5May21'.png'.png IAC settings 5May21'.png'.png
A datalog of the issue would be very helpful, this way I can see what is changing during the event.
Do you have any idea what your injector timing is?
 

AwxyMoron

Member
Apr 3, 2021
34
9
18
21
Ohio
A datalog of the issue would be very helpful, this way I can see what is changing during the event.
Do you have any idea what your injector timing is?
Not exactly sure how to find injector timing or what it is. I see injector end angle which is -90 degrees and injector reference angle which is at 50 degrees which I set according to the install book for the holley dual sync
 

a91what

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Apr 6, 2011
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@Noobz347 can we please get the .dl and .terx files added to the acceptable list.

I would start by investigating the 1D table again, the terminator uses very simplistic approaches to idle strategy... this is nice for some builds and for others that have issues it can be a chore to find work arounds.
 

Noobz347

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@Noobz347 can we please get the .dl and .terx files added to the acceptable list.

I would start by investigating the 1D table again, the terminator uses very simplistic approaches to idle strategy... this is nice for some builds and for others that have issues it can be a chore to find work arounds.
I'll do so long as you're keeping an eye on cleaning these files up when they're no longer needed. Users should be removing them once they're finished with them.
 
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a91what

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Mod Dude
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I'll do so long as you're keeping an eye on cleaning these files up when they're no longer needed. Users should be removing them once they're finished with them.
uhh... nope they usually hang around as example when I send back changes for users... should I just have them zip the files from now on??
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
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uhh... nope they usually hang around as example when I send back changes for users... should I just have them zip the files from now on??
They get crunched anyway. Those files that are of no more use (initial startup files etc.) should be removed.

Otherwise, we will reach a point where we're accumulating useless data to the point where they get cleaned out indiscriminately from the Admin CP.

The files are generally small so some accumulation is fine. Members should try and keep that pool down to only those files that are still useful and nuke the ones that are not.

I would say that files kept specifically as examples are still useful.
 
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AwxyMoron

Member
Apr 3, 2021
34
9
18
21
Ohio
@Noobz347 can we please get the .dl and .terx files added to the acceptable list.

I would start by investigating the 1D table again, the terminator uses very simplistic approaches to idle strategy... this is nice for some builds and for others that have issues it can be a chore to find work arounds.
Okay, It let me post the files this time, I should note that I was NOT using the 1D table when I recorded those datalogs
 

Attachments

  • Fox 8psi Tune.terx
    101.6 KB · Views: 9
  • Warm Idle Open Loop, No IAC, No Spark Adj.dl
    2.7 MB · Views: 6
  • Warm idle.dl
    4.6 MB · Views: 5

a91what

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Mod Dude
Apr 6, 2011
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In closed loop the idle valve has some very erratic behavior, the surging is the idle valve trying to overcorrect. Build a 1D table and get a log file
 

AwxyMoron

Member
Apr 3, 2021
34
9
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21
Ohio
In closed loop the idle valve has some very erratic behavior, the surging is the idle valve trying to overcorrect. Build a 1D table and get a log file
Thats not the 1D table I have saved in the tune I sent you, i lowered the values a little bit because it wasnt idling below 1050 with the IAC set at 40%
 

Attachments

  • IAC 1D Table idle.dl
    2.8 MB · Views: 2