E40D - tach is acting funky and trans is shifting hard

[OB_WAN]

1990 F-350 4x4 7.3L IDI w/ an E40D, 175k miles(unknown mileage on "new" tranny)

I just purchased this truck a week ago. Have been driving it fairly regularly with no known issues(has extra cooler, no temp probs, ran fine on long trips and short trips). This is my first diesel and my first Ford so it's hard to say. Previous owner said he had it replaced with a heavy duty upgraded factory trans when the original went out(whatever that means).

This evening I hopped in the truck to run down and get some gas. First thing I notice is that it's shifting really hard(1st->2nd, 2nd->3rd). I then notice that the tachometer(RPM guage) is hopping around. I get some gas and then on the way back, the transmission is acting like it's not quite sure when/how to shift and the tach is again bouncing. but at cruise speed(35mph or so) the tach is showing 0. I push on the gas a bit and the tach hops back up to 1500-2000 and as I let off the gas to cruise again it drops back down to 0.

Any ideas/suggestions?

I was so excited to have an IDI after reading this forum. I also got a truck that was meticulously cared for in the hopes I wouldn't have probs. guess my luck is really working these days

 

[Dirtleg]

I just went through a similar issue last week with my E4od. I lost the speedo input and the transmission went into limp mode (hard shifting /OD light blinking). I fixed the speedo problem (blown fuse) and the trans is back to normal.

I would say if you are having erratic signal from the tach that is where your problem lies. Fix the tach issue and it should fix the tranny issue.

 

[GenLightening]

You can try to remove the sender (large nut with 2 wires, next to the oil fill neck) and see if there's any crud on the end. If cleaning it doesn't help, then you'll need to go to Ford an order a new sender. Part # E5TZ-17B384-A

 

[NextENRG]

i have the same issue, i noticed that when the tranny shifts to od (lock tc) the tach signal will drop below 1k telling the tranny to downshift. the higher rpm causes the tach sensor to be more accurate and the tranny will lock tc starting the cycle again. does this sound like your issue?

i asked my local part store for a "tach sensor" and didnt list one. does the part next to the 710 cap with the 2 wires go by another name?

also in D im getting no power delivery to the wheels.....if i shift 1-2-d with speed it runs normal with medium harsh shifts i recently added dilectric to the harnesses because i had a problem with water causing abnormal shifting.

any thoughts?

 

[NextENRG]

wow 2 posts before i could post

 

[LCAM-01XA]

When the tach sender fails it usually still read accurate above 1000 rpms, but below that it just drops to zero. So yeah, technically if you do fall under 1000 rpms upon upshift into any gear, it could send the trans into semi-limp mode. What I wonder tho is, how come you manage to drop under 1000 rpms with an E4OD? The worst I've seen mine do is go from 3rd over to 4th over and drop like 500 rpms at once, bringing me right at 1100 rpms - makes for some smoke if it happens while I'm slowly accelerating uphill, but even when my tach sender was shot it never acted weird cause of that.

By the way, you won't find the tach sender in the parts stores, it's a dealer-only item.

 

[OB_WAN]

thanks a lot for the quick response. I'll check the tach sender tomorrow.

 

[NextENRG]

well its accurate above 1k so ***** footing it around 60kmh its will shift to od, which drops rpm down i think in my case to an inaccurate tach reading confusing my poor e40d. i have not seem od light flash though im certain she goes into limp. if it was standard, D feels like im trying to start in 5th by feathering the clutch. it does get going and shifts very very light and will lock tc at the regular speed.

when i run her from cold there are no issues. then with no warning ill try to take off from a light and all show but no go. also i can take my foot off the brake in d while stopped and she wont roll like in 1,2,or r

maybe flush and fill along with sensor?

 

[GenLightening]

Check all the connections going to the trans, clean and use dielectric grease in them. You may also want to check out the Tech section and look up adjusting the FIPL and other components.

 

[OB_WAN]

I pulled the "Engine RPM Sensor" aka "Engine Speed Sensor" (named both in alldatadiy). It had a little bit of old oil on the end but no significant buildup so guessing it's dead or dying. I'll go ahead and get a new one and drop that in to see if it fixes the problem. I did notice the wires were not "sealed" in the top of the sensor, looked like whatever was supposed to seal them was melted away. Perhaps previous owner used a pressure washer to clean under the hood and shorted out the sensor(the engine looks way too clean for a 20yo truck

Here's a good summary posting I pulled from ford-trucks.com (searching via google for tach sensor). Aligns well with what you have suggested:

Tach sensor .........best guess

The 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.

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.

 

[LCAM-01XA]

Thing with testing it is tho, it ain't accurate - my tach sender passed the resistance test, but it was still semi-dead.

 

[typ4]

I highly discourage flushing any automatic trans. Drain the trans and TC, drop the pan, new filters,refill. flushing loosens all the packed in metal and then it goes thru the trans and after that its all over. I have seen this several times, people bring me a car/truck with a bad trans, the first thing I ask them is when was it last serviced, the answer I get is " I had it flushed a week ago" . It is your truck but I dont like flushes.

 

[NextENRG]

I highly discourage flushing any automatic trans. Drain the trans and TC, drop the pan, new filters,refill. flushing loosens all the packed in metal and then it goes thru the trans and after that its all over. I have seen this several times, people bring me a car/truck with a bad trans, the first thing I ask them is when was it last serviced, the answer I get is " I had it flushed a week ago" . It is your truck but I dont like flushes.

this makes sense and im going to take your advice on it. recommended tranny fluid? i was told ford type "F" cause it does not contain friction modifiers....

Thanks for the ford part # Doug....was 100$ here in canada......(lame)

 

[LCAM-01XA]

Do NOT use Type-F, that's for power steering pumps and some very old transmissions - you need your regular Dextron/Mercon III fluid, and some people upgrade to Mercon V but that's not required.

 

[NextENRG]

MLSC, just curious but why the emphisis on DO NOT? what will happen? was told that the dexron/mercon contain friction modifiers that cause the clutches to slip a little to provide a smoother shift. the type f doesnt have the modifiers and there will be better power delivery and firmer shifts....?

seems you have the same truck as me....got a pic? id like to see the "cow catcher" and 1000w+ of lighting lol