The Mighty 258 > General Service and Diagnosis

cold start,idle,retard signal sensor?

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2xEaglewagons:
Happy snow day!
Start out with a positive note,my eagle is unstoppable in the snow,lifted with studded snow tires!
Been racing(on track legally) and working on my own cars for 40 yrs,mostly 50s 60s 70s cars.
Sold everything years ago but kept a convertible A body and my 1958 tri power race car.
Always said i would never buy another car but always wanted an Eagle since they came out.
Have bought 2 Eagle wagons in the last 3 yrs and loving it!
1987 is my daily driver,200km,,the 1985 is low miles 100km with all options,very clean.
The 85 is getting a full going threw and unable to drive at the moment.
Must agree with others and say they are difficult to work on at times.
I hate wires/elec. and dont know the emissions and multiple sensor computor stuff very well.
I do know the Eagle is doing exactly what the slant 6 1986-87 dodge van i used to have did all the time.
Winter starts sucked until warm...thumpa thumpa thumpa ,like a retarded timing signal.
If i warm up the Eagle she will cruise and power hi way no prob.
At a stop light her idle is thumpa thumpa.
Shut her down at the store home or fueling up for a moment,start her up her idle is purring like a kitten.
It will stay purring until i drive.
Go cruise a bit then the next stop light or two her idle is back to crap?
info on car..
New needle and seat/rebuilt the carb,unplugged stepper motor with metering pins showing 1/8 past beveled shoulder.
Fuel lines new,fuel pump,filter in tank removed,Fuel filters new,return line higher then carb line.
Did the "another bypass" I read about on web,bypassing comp.,added a new module for good measure.
Disconnected egr with vac line plugged,,no choke or air to flapper door in air cleaner.
No cat,just a muffler.
I prefer the pump/squirt feather it a bit till warm approach to cold morning starts,never had a problem.
Recently did the heater core but thats another nightmare and unrelated problem,lol.
It is an AC car with new rad and clutch fan,wont over heat if ya tried :).
Timing is good,new plugs wires cap rotor,still running stock vac line to dis.
Was considering running a line for vac advance straight to carb.
This condition of poor idle only happens in cold weather,summertime no problems.
I thought it maybe rich and loading plugs but the intermittent perfect idle tells me otherwise.
Narrowing it down to what ever is giving a retard signal to ignition timing?
How many degrees can a mcu or ecu or emissions crap retard timing?
Looking in the shop manual unplugging knock sensor alone is not enough?
You have to run a jumper form the plug to grnd?
Is there another temp sensor i am missing that could retard timing?
I could be wrong and its a temp sensor for PCV or other carb vac related cold/hot transition?
Oh i almost forgot,air bleeds are tight and blown clean regularly with carb clean.
Did more testing today,idles beautiful if turned off and restarted a few min later.
After driving even a short distance idle smells rich or sounds like retarded timing.
Only happens in winter,all good in summer.
My guess is a emissions temp switch?
The idle on this car in winter is the only thing keeping it from being perfect.
Ant hints or help is very appreciated!
Randy H.
Mission B.C.
1985 Eagle wagon
1987 Eagle wagon
1958 88 J2 Olds
1972Olds Cutlass convert.

amcfool1:
hi, and welcome to the den. are you in Canada? seems like you have a lot of knowledge already, more than most, so, what is your actual question? The way I understand your post, is that you did the ECM Test, correct? so, all those sensors are now out of the loop and irrelevant, right? The ECM and stepper motor are no longer funtional. OK, so, you have an idle problem in cold weather only, right? An old school fix was to drill out the idle tubes to +.032. you will need a wire gauge drill set for this, and do it BY HAND., or if you must, with a Dremel at its LOWEST speed. May be some crap in those tubes that ices up in cold weather.
Next, check the solvac, this is what actually controls idle on late AMCs., may be freezing up.
next, check choke pull off, make sure it's getting good vac, and is nor seizing up.
good luck, gz

2xEaglewagons:
Hello
Thanks for the help,,Yes in Canada.
I dont know why ECM test was posted,i never typed that?
Changed to what i meant without saying nuutter.
She wont die idling,but its a rough idle.
It was suggested carb was icing up,wedged closed flapper in air cleaner to use 85 percent heat stove pipe air.
Did not help.
Not using the solvac on carb or a choke.
I am having no problems getting up to operating temps.
I am almost certain a sensor is sending the wrong message.
She idles perfect after shutting her down a few moments at operating temperature.
Randy(I wont give up)H.
Mission B.C. Can.





--- Quote from: amcfool1 on December 10, 2016, 08:40:00 PM ---hi, and welcome to the den. are you in Canada? seems like you have a lot of knowledge already, more than most, so, what is your actual question? The way I understand your post, is that you did the ECM Test, correct? so, all those sensors are now out of the loop and irrelevant, right? The ECM and stepper motor are no longer funtional. OK, so, you have an idle problem in cold weather only, right? An old school fix was to drill out the idle tubes to +.032. you will need a wire gauge drill set for this, and do it BY HAND., or if you must, with a Dremel at its LOWEST speed. May be some crap in those tubes that ices up in cold weather.
Next, check the solvac, this is what actually controls idle on late AMCs., may be freezing up.
next, check choke pull off, make sure it's getting good vac, and is nor seizing up.
good luck, gz

--- End quote ---

AMC of Houston:
Ditto on the plugged idle bleed tubes.   Was an AMC Service Bulletin, says to drill out the bottom of the tubes to 0.032.   That fixes a multitude of BBD issues, especially a rough idle.

amcfool1:
sorry, you wrote that you unplugged the stepper motor, and did "another bypass' that is the ECM Test bypass. good luck, gz

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