'93 Ford E350 with E40D - slips/bucks when downshifts from OD to 3rd
This problem just started on our way home from Ohio. I have a ‘93 E350 Class C motor home and I was in OD heading up an incline when the transmission downshifted in to 3rd it started bucking/slipping badly and stopped as soon as I turned the OD off. If I turn OD off on shifter - no problems - RV runs fine. If I turn on OD it runs fine UNTIL the tranny downshifts in to 3rd (up a hill). Then it will ‘slip’ or ‘bucks’ in 3rd until I turn the OD off and then it starts running fine again.
Couple of additional notes - just checked the fluid - it’s full, red and doesn’t smell burnt at all. I have a trans temp gauge and trans temp hardly ever goes above 180F. Transmission was rebuilt 3 years ago (<10k miles).
Just pulled back on interstate and shifts fine up through 3rd gear (I turned OD off).
But - if I do not turn the OD switch off on the shifter the Coach will not go in to gear when I shift (it will go in to Reverse). Turn the OD off and the coach shifts normally from 1st to 3rd gear.
Pulled codes and I got Code 512 and 553 - but I'm not sure these are related to this issue.
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Just a thought but the E350 chassis was built with an OD transmission giving the user the opportunity to use OD in the appropriate situation. Appropriate meaning lightly loaded on flat ground. With the weight of a motorhome, it's no longer lightly loaded and OD shouldn't be used.
have it looked at, ican be the plug in trans loose
A vacuum leak, defective transmission module, or bad throttle position sensor could cause this issue is talked about..
sorry for typing errors in last post.. . bad on my phone.. LOL
In my last 15 years of old ford iron..
in my 94, we had that issue intermitent came, go , came.. I changed fluids, changed brands as I found some oils way better, I toed a 7K trailer behing RV for many miles, I bought her with about 138K.. Around 160Kish.. That cut out, slap, surge from OD happened alot until one trip, it was nasty but also my speedo needle was jumping 3-5 mph..
To shorten my going grey on this one.. Trans shops, searched for a good rebuilder or a jasper... ready to pull plug..
I went to an event that idid twice a month..A local tech school teacher I knew was there. auto technologies/powersports etc.. he was teaching my son..
He said tranny seems strong as I had trailer on.. did you check the PSOM/VSS circuit, these trans are sensitive to vehicle speed.
Found a broken frayeed wire in the twisted pair coming from rear axle up frame rail near fuell tank. broken in harness with a few strands shorting each other.. I actually drove with a small snap on scope on wires , to watch the wave as I drove , and saw the drops and spikes etc.
I had few more twitches on the 94 and it was a bad PCM/ECM main computer.. it always had a idle stumble too . once i replaced it, trans shifted so much better, firmer and ran incredible, Sold it at 196K still going..
Fast forward, I updated, I am chaeap.. Found a 96 winnie 29RQ, 30K. sweet .
On my way home from NY to PA.. it ran great, then 30 miles from home the bang, clack, in / out of OD, then I saw the speedo twitch.
This one was a stinker,, ran a new VSS connecter at rear and sensor, and a new wire from there all the way to th dash speedo cluster . as the issue was at a splice in the dash area and i was not pulling it, I had it narrowed from ABS to cluster.. Any way, drove it first time this year yesterday for a couple hundred miles, and all is still working.. LOL
good luck,, just saying could be many things.. that trans was noted for that issue..
Thanks for the replies - I was wondering about the possibility of this being electrical. I have noticed a 'dead spot' for years when I set the cruise right around 62-63 mph - a slight surging being noticed as the coach runs with the cruise on at that speed on level road. Speed up some, slow down some and the motorhome runs smoother (TPS??).
On this trip we got home just fine - turned the OD off, set the cruise at 58 mph and the coach ran great! Seems to be a 'sweet spot'...
The only question about it being electrical - I don't see how that effects the initial shifting in to gear. When you turn the RV off and restart it, the default is the OD is on (I have a button on the end of my shift stalk that turns the OD on/off). If I try to start out with the OD on (light off on the stalk), I can't get the tranny to shift in to gear - turn off the OD - no problems. And, if I turn off the OD with the RV in Drive, I can feel a noticeable lurch - as something is 'switching on/off??). Once the OD is off, RV shifts perfectly up through 3rd gear and runs fine.
I had the transmission rebuilt 3 years ago and I called the shop. They indicated that I could drive it indefinitely with no OD, but I'm going to have them look at it. Hopefully, they'll work with me in fixing it - I gotta believe a rebuild should last longer than 10-12K miles.
I am going to further explore the electrical issues though...just not sure how.
Thanks, ryan
I did develop ball joint issues on our last leg- really loud creaking...but I'm going to post another thread
Bringing this back up as I was hopeful it was an electrical problem, so I replaced the MLPS (neutral safety switch) as I still had the old style switch. Unfortunately, no difference.
RV is still doing the same thing - if after I start it, I leave the OD on and shift in to Drive, the camper won't go in to gear. If I turn OD off, RV shifts normally from 1st to 3rd and drives in 3rd gear just fine. If I'm on a nice flat stretch driving in 3rd and turn OD back on, OD engages and RV runs fine - UNTIL it has to downshift. Then it acts like it's in neutral. I can recover if I turn OD button off again.
Everyone I've talked to locally is stumped. Online I've had one suggestion that the OD one way clutch is bad and so the coast clutch is engaged which is what is then holding the OD unit (a local e4od guy though told me he has rarely seen this clutch go out, so I don't know).
Thanks for the reply -sounds exactly like what's happening with mine, but this updated sprag and clutch kit does not appear to fit my '93. The part # that fits mine is very close - F3TZ-7A089A - but it shows "Discontinued"... So maybe this F5TZ-7A089A would 'retrofit'??
Transmission maintenance is the single missed item that leads to tranny problems. When was the last time the tranny had the filter and oil changed.
Ken
__________________ Amateur Radio Operator (KE5DFR)|No Longer Full-Time! - 2023 Cougar 22MLS toted by 2022 F150, 3.5L EcoBoost Tow Max FX4 Lariat Travel with one Standard Schnauzer and one small Timneh African Gray Parrot, retired mechanical engineer
This problem just started on our way home from Ohio. I have a ‘93 E350 Class C motor home and I was in OD heading up an incline when the transmission downshifted in to 3rd it started bucking/slipping badly and stopped as soon as I turned the OD off. If I turn OD off on shifter - no problems - RV runs fine. If I turn on OD it runs fine UNTIL the tranny downshifts in to 3rd (up a hill). Then it will ‘slip’ or ‘bucks’ in 3rd until I turn the OD off and then it starts running fine again.
Couple of additional notes - just checked the fluid - it’s full, red and doesn’t smell burnt at all. I have a trans temp gauge and trans temp hardly ever goes above 180F. Transmission was rebuilt 3 years ago (<10k miles).
Just pulled back on interstate and shifts fine up through 3rd gear (I turned OD off).
But - if I do not turn the OD switch off on the shifter the Coach will not go in to gear when I shift (it will go in to Reverse). Turn the OD off and the coach shifts normally from 1st to 3rd gear.
Pulled codes and I got Code 512 and 553 - but I'm not sure these are related to this issue.
Any thoughts?
thanks, ryan
First things first Ryan, you did great providing the codes. The 512 is a Keep Alive Memory code indicating keep alive memory power was lost... I have seen this as the only code before and caused by battery changes or in RVs turning off the chassis battery. It can also be the only indicator the ECM has taken a dump when it comes back repeatedly. The 553 is a pulse air valve code, and sets when the vacuum operated diverter valve fails to function(flow), commonly caused by a vacuum problem such as missing or broken vacuum hoses etc. In rare cases it can be set when the valves are commanded on when the available vacuum is low under a heavy load ie. full throttle. IF you do not have air injection you should not have this code and it can be an indicator of a failed ECM.
The E4OD transmission was the next generation of the C6, adding a fourth gear overdrive and electric shift control. They are a tough transmission and can give years of trouble free service when treated well.
I would definitely be going back to the guys who did your rebuild and work with them to fix the issue. Most of us that rebuild transmissions have pride in our products, and take it personally when one f^cks up. I think you have a transmission controller failure, but without being able to physically dig into it I can't say for sure. Work with your tranny guy, I think it is your best bet. By default tranny shops now have to be good at electrical problems, sometimes just to prove their rebuild is not the problem. It is how I got started working on transmissions, diagnosing the other problems causing the perceived transmission failure.
Just throwing this out there....as sometimes it's the little things that can cause big problems. I have a '93 E350 with E4OD chassis Winnebago Min Winnie....started shifting similar to what yours was doing. Had it serviced and checked out...they found nothing mechanically wrong. Was messing with the OD shift button on the shifter when the OFF light turned red then went out. Replaced that little switch with a Ford part and all is good now....shifts like butter and no problems. FYI
First things first Ryan, you did great providing the codes. The 512 is a Keep Alive Memory code indicating keep alive memory power was lost... I have seen this as the only code before and caused by battery changes or in RVs turning off the chassis battery. It can also be the only indicator the ECM has taken a dump when it comes back repeatedly. The 553 is a pulse air valve code, and sets when the vacuum operated diverter valve fails to function(flow), commonly caused by a vacuum problem such as missing or broken vacuum hoses etc. In rare cases it can be set when the valves are commanded on when the available vacuum is low under a heavy load ie. full throttle. IF you do not have air injection you should not have this code and it can be an indicator of a failed ECM.
The E4OD transmission was the next generation of the C6, adding a fourth gear overdrive and electric shift control. They are a tough transmission and can give years of trouble free service when treated well.
I would definitely be going back to the guys who did your rebuild and work with them to fix the issue. Most of us that rebuild transmissions have pride in our products, and take it personally when one f^cks up. I think you have a transmission controller failure, but without being able to physically dig into it I can't say for sure. Work with your tranny guy, I think it is your best bet. By default tranny shops now have to be good at electrical problems, sometimes just to prove their rebuild is not the problem. It is how I got started working on transmissions, diagnosing the other problems causing the perceived transmission failure.
good info...lets hope the trans shop is a good one...
I had almost pull my transmission .. it had lots of miles 140k+ it would jump out of OD alot, it then started to only work in 2nd, drove back from NJ to Northeast PA at 45-50mph..at over 3000rpm.. urgh..
Next day it worked fine,, then got worse.. my sons auto tech teacher said check the VSS found a short between the signal wires and another break shorting to ground... It was just enough of a signal drop to mess with transmission but barely casue the speedo needle to bounce, it was a suttle sway a couple mph that i though was normal..
in my next RV same crap, but speedo dropped out. trans defaulted to 2nd gear.. broken or critter eaten wire behind dash
SO YES trouble shoot electronics are key in many units..
Linear Mode
