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Topic: Idle is "hunting" (Read 1114 times) previous topic - next topic

Idle is "hunting"

My idle is hunting.Up and down.I am unsure what the problem is.I believe I have the vacuum lines good to go.They weren't leaking anyway,they were just here and there.What problems cause this to happen?I may just run the car down town this week and have someone let me know.I really don't want to spend hours and hours troubleshooting when I have plenty to do as it is.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Idle is "hunting"

Reply #1 –
i think generally a hunting idle is a lean fuel mixture, at least thats what ive been told. and theres the IAC that could be mushed up, EGR could be dumping too much exhaust in etc..
1987 20th Anniversary Cougar, 302 "5.0" GT-40 heads (F3ZE '93 Cobra) and TMoss Ported H.O. intake, H.O. camshaft
2.5" Duals, no cats, Flowmaster 40s, Richmond 3.73s w/ Trac-Lok, maxed out Baumann shift kit, 3000 RPM Dirty Dog non-lock TC
Aside from the Mustang crinkle headers, still looks like it's only 150 HP...
1988 Black XR7 Trick Flow top end, Tremec 3550
1988 Black XR7 Procharger P600B intercooled, Edelbrock Performer non-RPM heads, GT40 intake AOD, 13 PSI @5000 RPM. 93 octane

Idle is "hunting"

Reply #2 –
So many options..............
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Idle is "hunting"

Reply #3 –
Hunting idle is rich not lean.
The eec tries to get a perfect 14.7 to 1 at idle but if everything is not set perfect(ie: tps .96v,iac clean,o2s functioning correctly,idle set at 650rpm,i believe)then it will not achieve the correct AFR and therefore will "hunt" for the correct mixture.
With my wideband i can watch exactly what happens when the mixture tries to set itself,goes rich then the eec tries to lean it out too much then goes rich then the eec tries again,etc,etc.
Make sure all is set correctly then try again.

Idle is "hunting"

Reply #4 –
I need to make sure the timing is right,then I'll try to get to everything else.My idle is around 1300.....yes,I said 1300.It's insane.I'm going to step back until tomorrow.The car is running strong,but I want strong and "right".I'll let you all know what i find.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Idle is "hunting"

Reply #5 –
Well,today the car is idling around 1100 rpms.Sounds good,but still feels too high.I'm thinking  about removing the phenolic spacer and checking for a vacuum leak.There aren't any leaks anywhere else.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Idle is "hunting"

Reply #6 –
Check your TPS voltage when you finally get your idle where you want it.  What cam are you running anyhow?
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Idle is "hunting"

Reply #7 –
My cam is the stock H.O Mustang cam.The engine is a stock short block with ported E7 heads and an Explorer intake with BBK headers.
'88 Sport--T-5,MGW shifter,Trick Flow R intake,Ed Curtis cam,Trick Flow heads,Scorpion rockers,75mm Accufab t-body,3G,mini starter,Taurus fan,BBK long tube headers,O/R H-Pipe, Flowamaster Super 44's, deep and deeper Cobra R wheels, Mass Air and 24's,8.8 with 3.73's,140 mph speedo,Mach 1 chin spoiler,SN-95 springs,CHE control arms,aluminum drive shaft and a lot more..

Idle is "hunting"

Reply #8 –
Your idle should be around 750 without any problems.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!
 

Idle is "hunting"

Reply #9 –
My 85 has a 302 CFI which is stock and lately it's been getting varying gas mileage and the idle has been higher than normal, but we found that by cutting it off and restarting it would come back down ... for a few minutes until we next accelerated and it would stay high again.  This would go on for about the first 15-30 minutes normally, and if it was really cold out, it would re-occur. 

Not vacume lines.

Not PVS.

Not EGR.

Not throttle kicker.



Today, found wire leading from alternator back broken right at wire loom at back of alternator, and other end feeds up through plastic loom to what would be the electric choke if it had a carb, but it doesn't.  Same function though, not sure of terms.  I was able to splice on a new wire, soldered connection, feed throgh loom, spliced nice factory connector other end, soldered, taped up, secured, started and it runs mighty near perfect now!

Not sure if wire broke due to fatigue or if maybe I unknowingly broke it while changing front right side plugs back in the fall. 

It's been aggrevating and a bit costly in terms of lousy gas mileage to say the least.