I'm stumped - '93 Ford E350 lurching under load (Motorhome)

Connie

FISH ON!!!!!!!
Joined
Nov 14, 2006
Messages
855
Likes
0
Points
16
Age
119
Location
Centralia, WA
#31
do you have the infamous E4OD automatic transmission??? My guess is yes. They are notorious.... You said you changed the fluid in it not long ago? Did you have this problem before you changed it?? Oh, and by the way, ALWAYS pull the hills with the overdrive OFF!!! Never pull hills in overdrive or you won't have a transmission much longer...especially with an E4OD. Back to the problem at hand... The E4OD is an electronically controlled transmission-hence the E part of the E4OD. There is a wiring harness with a plug that plugs into the right hand side (you facing the truck at the hood looking towards the back end) of the transmission towards the rear of the tranny housing and towards the top. It MUST be soundly connected with an excellent connection or the internal PSI of your transmission goes from somewhere close to 200 psi to almost 2,000 psi and things start to break in there. If there is even slight corrosion in the plug/connector, and it is having an intermittent short or loss of connection, you could be feeling it with a hesitation-jerking especially under load or when the vehicle is warmer and insulation on the wiring becomes more pliable, allowing more movement of wiring. I know it sounds a little odd, but I assure you from several previous E4OD repairs and replacements-both my own as well as customers, it is a fact. When you changed the fluid, did you come in contact with that wiring harness at all? The plug is designed to be extremely difficult to disconnect without breaking off an ear or retainer clip so that it doesn't randomly unplug accidentally. If you disconnect it, make SURE you reconnect it with new dielectric grease and the retaining ears are tight. Just a thought... Connie
 
Joined
Aug 28, 2007
Messages
4,747
Likes
24
Points
38
#32
Your posts brings back not so pleasant memories of the same era Ford AXOD"E" with similar problems. Like 1-2 shift slips, permanent torque converter lockups, and constant erratic shifting into OD that could be either mechanical or electrical problems.

But by some mysterious force, one could tell if these were transmission or engine hesitation or surge problems. Not easy to describe, but definitely distinguishing when driving the vehicle.

Good point, Connie.
 

rgnprof

Jr. Member
Joined
Nov 14, 2006
Messages
29
Likes
0
Points
0
#33
Thanks for the follow-ups...Yes, I have the E40D transmission and I will check the wiring harness. I don't remember, but I'm pretty sure my lurching problems preceded my changing the transmission fluid. I will definitely check the wiring there though...

It has been so hot here that I haven't been able to do much of anything outside - 108 here today and the same for the next month probably! Just miserable...

ryan
 
Joined
Aug 28, 2007
Messages
4,747
Likes
24
Points
38
#34
Also had brake and neutral safety switch problems not making good contact in these things. Four solenoids as I recall that need full constant voltage to do their thing.
 
Joined
Feb 13, 2019
Messages
1
Likes
0
Points
1
#35
Sorry this is long, but I have posted questions related to this issue in other RV forums - let me try to be thorough, but succinct as possible. I have a '93 Cobra Passport on a Ford E350 chassis with a 460 EFI motor, with 62,000 miles. The "first" problem was that the coach would just cut out after driving it for several hours (almost like it was vapor locking)- seemed to be worse when hot. After much reading and research, I troubleshot a bad fuel pump...

Replaced the fuel pump with an OEM Motorcraft pump and that problem has gone away. I also had the really loud, whirring idle speed control valve/motor problem and I replaced it with a BWD part and no more noise.

But, I have 'created' a new problem - the coach now lurches ONLY under load. Whenever I step on the gas - going up a hill, or even down a hill - the coach does not accelerate smoothly. If I back off the throttle some, it runs fine. Cruising at 65-70 on a straight flat stretch, it runs great! It also idles a little rough - more noticeably so when in gear...drop it in to neutral and idle evens out. I just returned from a 4000 mile trip and it did it the whole way - but other than that, I had no problems (even got between 8-9 mpg's). The engine has plenty of power - and even driving through the mountains in Wy and Montana it ran well. It would lurch slightly when the transmission dropped in to 2nd on the way up a steep grade, but once it started to even out up the hill, no lurching - would easily climb the steepest grades at 45, 50 55 mph. Generally, seems to run better with the OD off, and I had a friend suggest that the torque converter lock-up switch was not working properly. He suggested that when it did it again, touch the brakes while still accelerating and see if it stops lurching - tried that and it made no difference!

Here is what has been replaced:

1) Throttle position sensor (Motorcraft)
2) fuel pump and filter (Motorcraft)
3) idle speed control motor (Borg Warner)
4) ignition control module (fender mounted) (Motorcraft)
5) plugs (Motorcraft), wires (Belden from NAPA), cap, rotor (Autozone)
6) ignition coil (Motorcraft)
7) air filter
8) catalytic converter (Walker)

I changed the Transmission fluid at 60,000 miles and no particles - old fluid looked good. Other than this lurching on acceleration, coach runs great and I'm getting about as good gas mileage as can be expected! I have tried pulling codes several times and none are present - and I have troubleshot the EGR system and it seems to be functioning properly. The last thing I changed out was the TPS, and I really thought that was it - no such luck.

I have been tracking fuel pressure issues of late on the advice from another forum member - very helpful, but I'm still not positive about what is going on here.

He thought I was having fuel pressure problems, so I hooked up my pressure gauge and took it for a drive. KOEO pressure is 32 psi, at idle it is 28 psi and with hose pulled off the pressure regulator the pressure is 38 psi. At highway speeds and WOT I'm getting 36 psi. I wanted to see if pressure would drop when it started to lurch and it does not - the needle flutters some, but stays within 2 psi...when I let off the gas and coast, the pressure drops back to 30 psi.

Most think those pressures are low and at WOT it should be around 45 psi...I replaced the fuel pressure regulator with an extra one I had (ACDelco) and it made no difference - except I haven't been able to get it out and drive it yet...all other pressures are pretty much the same.

I am right now trying to figure out what to do about these pressure readings before I move to electrical/ignition stuff. Haynes indicates an engine running fuel pressure of 30-45 psi and Alldata says 30-40 psi - no real mention of what it should be at WOT.

I have been advised to just add an extra, inline fuel pump along the rail...I also received another new Motorcraft fuel pump today as a replacement, so I may pull the in-tank pump again. It's possible that something is wrong with that pump, or that the sock filter has clogged up (when I last replaced the fuel pump in April, I didn't empty all of the fuel, or clean the tank any).

Needless to say, I appreciate the help and I am still moving forward - I think!

ryan
Hi. The issue is with the torque converter partial unlock/lock management. You can check that by taping the brake pedal while the vehicle is "misbehaving" when the brake lights or hazard lights a