Hello, I'm back.

Having O/D issues. Suspect Tach related.

'93 F-250, 4x4, 7.3 IDI, E4OD. The tach shows zero at 'warm idle'. When I start it cold, it registers about 600 RPM. Once the idle kicks down, the needle goes dead to zero. On the road, when I'm coasting, the needle reads zero --- unless I'm going down steep grade, then it just barely shows life. When I'm into the pedal, the RPMs seem normal, but I am certainly no expert.

Whenever the tach is at zero, the OD OFF light flashes. It doesn't matter if I shift into "N", it still flashes. If I apply slight throttle pedal pressure to raise the RPMs (even slightly), the OD OFF Light stops flashing.

New to this truck, and to diesel, but the trans seems to shift flawlessly otherwise. It's smooth with no slipping under light acceleration, and is definitely more snappy if I am getting on it.

The OD-OFf swith seems to work just fine when I'm on the highway at cruising speed.

Pulled the 1" pickup sensor by the oil filler tube out. Looks like it might be the problem. I can see the conductor (the insulation has recessed) on one of the wires where it enters the sensor.

Questions:

What should the cold idle be? What should the warm idle be?

How can I remove the sensor, or actually install a new one without damaging the wires? The round pie-pan looking thing definitely causes interference and doesn't look like I should have to remove it to replace the sensor.

Am I doing damage driving it this way?

thanks!

 

Mine did like yours has, I did hoky repairs for couple years then replaced it ...replace it now and save your money and time doing 1/2 assed repairs.


E4OD info......In park/nuetral ..Cold idle with fast idle solenoid engaged .......850 +/- 50. Curb (hot) idle in gear auto should be 650 +/-50

I did mine with the vac pump installed...but lossening the bolts would help.

Driving the truck like that is hard on the trans.........fix it asap

 

Thanks. Just to be clear, you're saying to replace the tach sensor (not the E4OD) now instead of waiting, right?

Is that sensor a dealer-only part? Is mail order a viable option?

 

Tach sender......

A dead tach sender should/would send the automatic trans into a "failure management mode" (limp mode) with harsh engagements and firm shift feel and an abnormal shift schedule. It has no effect on a manual trans only the Tach readings.

Check the wires where they exit the big nut on the oil filler housing , known to short out due to bare wire.....

Replace the tach sender on the oil fill housing a big 1" nut with 2 wires. Ford only part Engine RPM sensor E5TZ-17B384-A about $50. You can remove and clean it but usually changed later too.

You can test it too, hold it in the air away from ferrous metal, using an ohm meter lead on each wire you need DC resistance between 2000-3000 ohms.

There is a Ford dealer sponsor on the left DirectFordParts check with them for mail order.

 

Thanks PLC.

 

Just a quick update:

I replaced the tach sensor, without loosening the vac pump. I thought I might be damaging the leads out of the sensor, but eventually I got in.

WHAT A DIFFERENCE

No more O/D off light, no more wierd shifting when decelerating or coming down an incline. The shift with WOT happens just before redline and it's FIRM. Other shifts are smoother, it seems as if it's hunting less for the right gear.

And, maybe it's just my imagination, but it seems like the cold and curb idle has smoothed out a bit.

So, just a thank you to this board and those that responded. What a resource this place is. I ended up ordering from DirectFordParts at the suggestion of this thread -- good guys and quick shipping, etc. Thumbs up to them.

I also ordered a new CDR valve, but didn't get that installed yet.

Thanks again!