89 f250 4x4 7.3

[Psolver]

2 problems if this is the right forum. The tach in my truck does not work at idle only when foot is on the accelerator pedal. I had my e4od trans upgraded and rebuilt, with an upgraded torque converter. when cruising I believe the TC is dropping in and out of lockup. Used the truck for the first time to haul some dirt in a dumping trailer an i don't think the trans was locking up . Any suggestions ?

 

[nostrokes]

Need to fix the tach issue before looking into the lock up. The e4 uses feedback from the tach for gear and lock up selection and it sounds like you're tach signal is dropping out.

 

[Psolver]

where to start with tach problem

 

[IDIBRONCO]

A new tach pick up is a place to start. That is the piece that screws into the upper part of the injector pump cover and has two wires coming out of it. You'll need a 1" open end wrench to replace it.

 

[Psolver]

any way to test the pickup been changed out once

 

[IDIBRONCO]

The only way that I know of is to switch yours out with one from a truck that works right. Maybe someone else will know of a different way to test it.

 

[nelstomlinson]

Check the wires which connect the pickup, too. They may be cracked and corroded, and making intermittent contact. I had that problem with a Powersmoke truck. Wiring in that rig is crap.

 

[Skidtech]

The only way to test it is with a lab scope. It should have a 16 pin 300mv spike wave form.

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[Thewespaul]

Old ford service manual says to test it by reading mV at hot idle, should have between 10-20 mV