Ford 289 unstable idle

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Ford 289 unstable idle

Unread postby my0wn3ds » Fri Jan 01, 2016 11:01 am

Hello and Happy New Year!

I have an issue with very unstable idle.
Tune is almost base A9L2 with some modifications:
Number of HEGO (1)
Injector output port (11111111)
Injector high slope (22)
Injector low slope (22)
Injector firing order (15426378)
Transmission type (any type with same result)
EGR type (2)

Please take a look at my attachments
Thank you.
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my0wn3ds
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Posts: 6
Joined: Fri Aug 29, 2014 5:54 am
Name: Andrey
Vehicle Information: 94'Mustang 289 EEC-IV Moates Quarterhorse, C4 TransGo
Vehicle 2 Information: 87'Cougar XR7 302 EEC-V project, AOD
Vehicle 3 Information: 93'Mustang 2.3L, T5
Additional Vehicles: 97'Ka 1.3L, RB5

Re: Ford 289 unstable idle

Unread postby ironmanisanemic » Fri Jan 01, 2016 2:11 pm

From what i can see is there is something wrong with your IAC Valve, in your logs its maxing commanding a higher % than whats possible. it could be a wiring issue, or an issue with the valve itself being shorted out. Second is its pig rich at idle. you need to lean it out and that combined with fixing your IAC should fix your idle issues for now. once you get it tuned the rest of the way it will idle even better. I didnt look at your tune yet, but from what i saw in the logs those were the only 2 things that stood out at me for a crap idle.
ironmanisanemic
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Posts: 163
Joined: Sat Nov 09, 2013 10:50 am
Location: Vandenberg AFB, CA
Name: Miles
Vehicle Information: 89 Ford Bronco - 393W, Professional Products 190cc heads, Custom Comp Cams hyd roller cam, Edelbrock EFI Mustang intake, 10:1 compression, 30lb TrickFlow injectors, ProM 80mm Mass Air Meter, 2-1/2" into 3" y pipe, no cat, and hooker aerochamber muffler. U4P0 computer with Quarterhorse and BE, EA. AOD with all of the goodies.

Re: Ford 289 unstable idle

Unread postby my0wn3ds » Fri Jan 01, 2016 2:37 pm

ironmanisanemic wrote:From what i can see is there is something wrong with your IAC Valve, in your logs its maxing commanding a higher % than whats possible. it could be a wiring issue, or an issue with the valve itself being shorted out. Second is its pig rich at idle. you need to lean it out and that combined with fixing your IAC should fix your idle issues for now. once you get it tuned the rest of the way it will idle even better. I didnt look at your tune yet, but from what i saw in the logs those were the only 2 things that stood out at me for a crap idle.


I replaced IAC with new aftermarket.
Idle warm up is great, but when engine is hot idle become unstable.
(it was no warm up rpm with old valve)

Engine wiring harness is custom, assembled from two pieces.
What kind of wiring issue is possible with IAC?
User avatar
my0wn3ds
General Poster
 
Posts: 6
Joined: Fri Aug 29, 2014 5:54 am
Name: Andrey
Vehicle Information: 94'Mustang 289 EEC-IV Moates Quarterhorse, C4 TransGo
Vehicle 2 Information: 87'Cougar XR7 302 EEC-V project, AOD
Vehicle 3 Information: 93'Mustang 2.3L, T5
Additional Vehicles: 97'Ka 1.3L, RB5

Re: Ford 289 unstable idle

Unread postby my0wn3ds » Fri Jan 01, 2016 2:45 pm

Is it possible to use Alfa-N with A9L + QH?

Or how to correctly disable IAC in A9L2?
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my0wn3ds
General Poster
 
Posts: 6
Joined: Fri Aug 29, 2014 5:54 am
Name: Andrey
Vehicle Information: 94'Mustang 289 EEC-IV Moates Quarterhorse, C4 TransGo
Vehicle 2 Information: 87'Cougar XR7 302 EEC-V project, AOD
Vehicle 3 Information: 93'Mustang 2.3L, T5
Additional Vehicles: 97'Ka 1.3L, RB5

Re: Ford 289 unstable idle

Unread postby ironmanisanemic » Fri Jan 01, 2016 3:58 pm

my0wn3ds wrote:
ironmanisanemic wrote:From what i can see is there is something wrong with your IAC Valve, in your logs its maxing commanding a higher % than whats possible. it could be a wiring issue, or an issue with the valve itself being shorted out. Second is its pig rich at idle. you need to lean it out and that combined with fixing your IAC should fix your idle issues for now. once you get it tuned the rest of the way it will idle even better. I didnt look at your tune yet, but from what i saw in the logs those were the only 2 things that stood out at me for a crap idle.


I replaced IAC with new aftermarket.
Idle warm up is great, but when engine is hot idle become unstable.
(it was no warm up rpm with old valve)

Engine wiring harness is custom, assembled from two pieces.
What kind of wiring issue is possible with IAC?


if the IAC is wired backwards it will burn up the diode inside the valve itself (i know from experience). There is a diode inside and if it gets wired up backwards the diode lets full voltage to run unregulated through it and burn up. so after that happens it doesnt matter if you fix the wiring, you will need to replace the IAC now that the diode is burned out and doesnt stop current flow one way. I would verify the polarity of the wiring harness is correct for the valve and ohm out your IAC. If it reads no resistance when you hook the leads up one way, and when you reverse the leads it still reads no resistance the IAC is shot. One way it should read some resistance. This indicates that the diode isnt fried, and the coil winding is fine. this will also tell you the proper valve wiring polarity.

As far as running Alfa-N, why would you want to? Alfa-N eliminates any air metering device (MAF/MAP) and fuels strictly based TPS and RPM. This wont allow the ECU to compensate for air density changes, elevation changes, etc... There may be a reason why this might be beneficial but i cant think of a situation. As far as the possibility goes, it may be possible, you could leave your maf unpluged and dial in the failed maf table, that would get you a sudo alfa-n setup. Ill let someone else chime in before i say anything else on the topic though.

It is possible to disable the IAC completely, but it does more harm than good to do so and its not hard to dial in once you get it working properly. It helps reduce/eliminate bucking at closed throttle/part throttle. It also helps eliminate conking out when returning to an idle or going into gear. Im sure there are other places that it is a benefit, but they escape me at the moment.

Z_ISCSW is what you would use to disable the IAC. Setting it to 00 instead of 3A will do the trick, by doing so you will have to set your idle using the throttle body set screw.

What i would recommend is getting your IAC fixed so it operates properly, dial in fuel and then follow the Idle 101 write up on this site and perform the mechanical idle setup within the write-up.

I had my Bronco running this way unknowingly before i realized my IAC was shot (had it wired backwards).

Hope this helps
ironmanisanemic
A+ Contributor
 
Posts: 163
Joined: Sat Nov 09, 2013 10:50 am
Location: Vandenberg AFB, CA
Name: Miles
Vehicle Information: 89 Ford Bronco - 393W, Professional Products 190cc heads, Custom Comp Cams hyd roller cam, Edelbrock EFI Mustang intake, 10:1 compression, 30lb TrickFlow injectors, ProM 80mm Mass Air Meter, 2-1/2" into 3" y pipe, no cat, and hooker aerochamber muffler. U4P0 computer with Quarterhorse and BE, EA. AOD with all of the goodies.


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