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  • March 28, 2024, 05:00:42 AM

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Author Topic: Diagnosing Stepper Motor?  (Read 10975 times)

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Offline ammachine390

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Re: Diagnosing Stepper Motor?
« Reply #15 on: April 27, 2011, 10:44:18 PM »
That's true too, but even with a bad o2 sensor, the stepper motor would still initialize, and would probably adjust mixture, however, it would adjust it wrong based on a bad sensor signal. It adjusts by just moving the pins back and forth.
Dan
1981 AMC Concord DL 258 Auto

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Offline IowaEagle

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Re: Diagnosing Stepper Motor?
« Reply #16 on: May 01, 2011, 01:51:30 PM »
Yes, the stepper motor continues to do its thing, even with a bad o2 sensor or a non working/disconnected egr valvel
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Not a Jeep.  Not a Car.  Its an AMC Eagle!

1982 Eagle SX/4 Sport;
1980 Concord DL;
1970 Ambassador 2 Dr HT, SST
2002 Hyundai Santa Fe;
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Offline Eagleearl

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Re: Diagnosing Stepper Motor?
« Reply #17 on: May 02, 2011, 10:24:23 PM »
I would check for a vaccum leak or stuck egr valve.

Offline RCielec

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Re: Diagnosing Stepper Motor?
« Reply #18 on: May 05, 2011, 10:13:43 PM »
Well, this is interesting. The actuator spring of the stepper motor was dislodged, broken in half and jammed into the well it occupies. Was in no postiton to actuate anything. I wonder if a backfire compressed the stepper motor sufficiently to allow the spring to dislodge.
Getting curiouser and curiouser.
Richard Cielec
Chicago, Illinois; U.S.A.
Richard Cielec
Chicago, Illinois

Offline RCielec

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Re: Diagnosing Stepper Motor?
« Reply #19 on: June 02, 2011, 10:50:43 PM »
Ahoy !
Finally got someone to help with the diagnostics. You know the situation: One person to keep the motor running while the other person pokes about under the hood. Anyway..
I think the cause of the problem is found: leaking intake manifold gasket. Sprayed carb cleaner around the joint and heard the idle change dramatically. Intake manifold leak is toward the rear and just in front of the last bolt the secures the intake manifold to the cylinder head.

Thanks to all for your comments. I learned quite a bit.

In truth, I have to think about whether to change the gasket or sell both cars (both have same problem). Frankly, I just don't have the time nor mental focus at present.

Richard Cielec
Chicago, Illinois; U.S.A.
Richard Cielec
Chicago, Illinois

 

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