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Discussion Starter #1
I have recently installed another 2000 model 4r70w from a mustang from a wreck due to radiator ruining my tranny. (Did the swap, re-pin 15 years ago along with the Jmod.) I wasn't able to drive it for 5 years and recently filled her up and started driving. It shortly after started what I thought was a misfire at light throttle/load until i scanned it and found a loose plug wire and all misfires went away. Well it still acts like a misfire but occasionally it is like a rapid fire machine gun and I have to let off the juice to stop it. I tried holding light pressure on brake pedal when it is acting this way to see if it would stop and it doesn't. I really don't want to drop it to replace the torque converter. Is there a possibility that it is the lock-up solenoid? Solenoid pack? Is the cheap $40 set from RockAuto worth a try? Mercon V is expensive but it is less than a shop who gets $400 just for the remove and re-install.
 

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The Parts Guy
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If applying the brake doesn't immediately cause the issue to subside, it isn't torque converter shudder. Application of the brake should unlock the torque converter clutch.
 

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My car had the same symptoms, and I would have sworn it was the converter one day and a misfire the next. It was hard to diagnose because they feel and sound so alike.

I did find a misfire and I did have to flush the transmission twice to get the clutch freed up.

Racecougar is exactly correct.

That said, you have to j-mod it anyway, so do that too while you are changing the pan and filter. Nobody told me that and it would have saved me 14 quarts of MerconV.

Best of luck to you, I look forward to the solution.

And FYI, it would be unusual for a coil to fail, but they do crack and then get wet and act weird.
I am not kidding telling you that those coils produce potentially lethal voltages. The current is small so it is extremely unlikely but it hurts every time.
I have measured over 50,000 bolts across just one. They both fire simultaneously, in a "wasted spark" configuration.

If I had an embedded pacemaker I would not touch them.

RD
 

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OP: it might need new spark plug wires. Get the Motorcrafts or Autolites.

I had coils go bad on two of our MN-12's. I'm sure it was just one coil, but I replaced both.

Obviously, the order of replacement for misfires is: plugs, wires, then coils. I had a misfire in both cars when climbing a hill in OD at 1200 RPM, and it required eventually replacing all three components to get the misfire to go away permanently, and not just come back a few months later.

Al
 

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Discussion Starter #5
I learned my lesson about coils back in 1985 when I was a youngun' trying to identify which cylinder was misfiring at idle. Apparently a dual point distributor and a bad plug boot will knock your u know what in the dirt. I don't mess with a coil on a running engine ... ever! I used Forscan and verified the misfires are gone (as the EEC sees it ). I am going to take a chance and drop the pan and change the solenoid pack and try that. All the fluid is new (3000 miles) and I will catch what I can if I can keep it clean. Damdest thing is I am getting 23-26 MPG as it is mostly highway cruise at 65. I tried the brake thing but it happens so quick I can't be absolutely certain, but it does seems to disengage the torque converter clutch, but it still seems to be oscillating just not as harsh? when I force a downshift to pass someone it sometimes shifts harsh like maybe the accumulator is sluggesh as it hesitates to downshift. I need to get the J-mod plate out of the previous tranny installed with the solenoids to see if it will correct any or all of it.
 

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I think you will be all set man, good luck and share how it goes.

Do not pee on an electric fence!

RD
 
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