cold start,idle,retard signal sensor?

[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.

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

[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

[2xEaglewagons]

Will try enlarging air bleeds,,also change needle and seat,my carb rebuild was two yrs ago.
Gonna throw in a new set of spark plugs again also.
This idle is driving me nuts!
The idle can be so clean and smooth and then turn bad.
Rechecked mixture screws,,tested,no fix.
Does the switch on pcv change from cruise to idle?
Something is changing between the transition of driving and idle,,vac?
Cruises/drives great,lots of power,idles good after parked hot,idle crappy after cruising.
Cold starts are rough.
Summertime idles great.
Randy(stumped)H.
Mission B.C. Can.

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

[AMC of Houston]

"The idle can be so clean and smooth and then turn bad." -- you just described the classic idle bleed tube symptom!

The electric solenoid on the PCV was meant to close off the vacuum at idle; and it didn't work out so well.  AMC had a recall on that to do away with the solenoid, and replace it with a hose that included a restrictor orifice in the hose.  I guess your car didn't have the recall performed.

[2xEaglewagons]

Thanks for the help!
Today i tried plugging the pcv port on back of carb,,no change,idled good drove a bit,idle bad.
It makes sense the idle tubes could be freezing up?
Really cold outside here.
Parking a few moments letting engine heat soak causes idle to be good,thaws out idle tubes?
Then driving the idle tubes freeze up i guess.
This is with the flapper door closed using 90 percent heat stove pipe air.
I figure the wind chill factor in carb is winning  the battle.
I did rebuild the carb cant remember where the idle bleed tube are?
Not the screw in airbleeds visible from top of carb?
Guessing i take top of carb off?
Will be doing this on the weekend,,need the car to and from work,no indoor space available here.
I cant help but to keep thinking of the knock sensor.
My ECM Test bypass takes it outa the picture?
I never did find it,,is it the red wire,orange wire going under the manifolds.
Just a little further rear of the carb,drivers side?
Thanks for the help,,,really appreciate it!
Randy H.
Mission B.C. Can.

"The idle can be so clean and smooth and then turn bad." -- you just described the classic idle bleed tube symptom!

The electric solenoid on the PCV was meant to close off the vacuum at idle; and it didn't work out so well.  AMC had a recall on that to do away with the solenoid, and replace it with a hose that included a restrictor orifice in the hose.  I guess your car didn't have the recall performed.

[amcfool1]

hi, the knock sensor is on TOP of the intake , just in front of the carb. usually has a red ring.  The red wire UNder the intake is the manifold preheater. idle tubes are in the venturi. two screws hold them in from top. good luck, gz

[2xEaglewagons]

gz
So i was correct on the knock sensor a week or so ago,Red ring  intake in frt of carb.
I grounded the plug lead like it said in shop manual,,no change in lousy idle.
The shop manual said the sensor was in the head,,,they should of said intake.
Guessing the ECM Test would have taken knock sensor out of equation anyway.
I just wanted to make sure.
Sounds like the idle tube are easy to get to,,i tighten those screws regular.
Loosen them and tubes come out also,,,great!
Please tell me about the manifold preheater,is it an elec coil?
Never knew there was a pre heater,when does it turn on or off?
Where is the switch?
Does the EMC bypass make the heater inoperative?
A preheater would probably help my cold starts.
Thanks again for the help!!
Randy H.
Mission B.C. Can.

hi, the knock sensor is on TOP of the intake , just in front of the carb. usually has a red ring.  The red wire UNder the intake is the manifold preheater. idle tubes are in the venturi. two screws hold them in from top. good luck, gz

[amcfool1]

the preheater works through a relay, small one inch cube next to horn relay on pass side inner fender. Bypass should not affect it. it't not a coil, but a sort of "porcupine plate" made by Bosch. activated by oil press switch I believe. google AMC 258 manifold preheater for a look at it. Not sure if its timed or temp turn off but should turn off after 2-3 min of running afaik. I live in Virginia!
when removing venturi cluster, be CAREFUL not to drop little check ball into manifold!!! good luck, gz

[2xEaglewagons]

Hello
We have solved the idle problem.
Ran a dedicated vac. line to dis. from carb lower port,shared with brakes.
Reset timing.
With a little mixture setting she purrrs idle..
Also blocked off the egr with thick alum. plate header collector gasket.
The chevy fuel pump block off plates i read on web to use dont fit/holes.
Even if they did the gauge is too thin.
A new egr was $80.00,,,i made a plate in 15 min.
The only vac. we are running is brakes,dis vac advance,4x4,dash.
All other ports on carb plugged/not used.
I should also add that the stepper metering pins pulled all the way forward worked best for my car.
To determine this we did lots of test and tuning,,hills and hiway.
Idle mixture screws turned out 4 turns.
Thanks for the help!!
This site and some of the jeep sites are priceless loads of info!
Good job!
Randy H.
Mission B.C.

the preheater works through a relay, small one inch cube next to horn relay on pass side inner fender. Bypass should not affect it. it't not a coil, but a sort of "porcupine plate" made by Bosch. activated by oil press switch I believe. google AMC 258 manifold preheater for a look at it. Not sure if its timed or temp turn off but should turn off after 2-3 min of running afaik. I live in Virginia!
when removing venturi cluster, be CAREFUL not to drop little check ball into manifold!!! good luck, gz

[vangremlin]

Glad to hear your Eagle is running great now!  May you have many trouble free miles in your future!