I have a 93 F150 with 5.0 and an E4OD transmission. It's an old state truck runs well but under moderate accelaration it bucks between gears. Mainly between 2nd to 3rd and 3rd to OD. The engine also pings at the same time. I've checked the distrubitor and timing and they operate and are set where they should be. Fuel is good I ran both tanks dry and refilled with 89 octane. When I run the error codes I get a code for the TCS which the book refers to as a transmission control switch or transmission control spark. None of my books tell where it is or what it does. Anybody have an ideas? I've read a couple of threads with similiar problems and they refer to TCS as Torque converter shudder. Is this one in the same problem? If I take it out of OD it does smooth out quite a bit but it's still there just not as harsh.

mcgyver

 

The trans control switch is the overdrive off button on the end of the shifter. If you don't press this button when you run the codes it will set a code for the switch.

The bucking or shuddering that you see has nothing to do with this switch. It is either an engine misfire or torque converter shudder. If you haven't changed the fluid recently, do it now. That will often fix torque converter shudder.

 

Ok changed transmission fluid from pan and torgue converter.... Ok it was kinda dirty. On advice from a Ford mechanic I added they're friction modifier. The transmission shifts much better now but I still having the spark knock and bucking under acceleration in 3rd and O/D. If you floor it the truck bucks a little bit pops and then takes off. This isn't my primary vehicle but I drive it ever day just to try and figure out what it is. It's getting quite annoying. Anyone have any ideas?

McGyver

P.S. no longer have any error codes

 

Sounds like a misfire.

Time for a tuneup? (plugs and wires)?

Maybe even a vacuum leak..

Steve

 

No no no! E4OD gets no friction modifier! Whole point of not using Mercon V which is just Mercon with a friction modifier.

And how bout doin the fuel filter too. You need a line tool.

Adrianspeeder

 

Absolutely correct, you cannot use HFM chemicals in an E4OD it will casue premature wear in the clutches. Have the tranny fluid fluched with straight MERCON (which for retail sale is almost always labled MERCON/DEXTRON III). Prolly didn't hurt anything if it's only been in a few weeks, but down the line it will.

G

 

Ok some background on the truck.... It's an old state truck apparently they were having the same problem. It has new cap, rotor, plugs, and fuel pressure regulator. When I initially started driving the problem seemed to change when you switched tanks. After testing the fuel pressure the rear tanks fuel pressure was low and didn't change when you disconnected the regulator. I corrected that by replacing the rear fuel tank pump. Fuel and flow are correct now. I've run both tanks dry and refilled with 89 octane and the fuel looked clear without any seperation after a day. I also ran the self test on the computer which gave me the TCS error code which has since been cleared. Currently it's not showing any codes. The distrubutor advances as it should during the test. I've been leaning toward the spark-knock sensor. Since there's always spark knock before the problem happens. I would think it would trip a code though.

Under acceleration would the computer advance the distributor until it detected the knock and then back off or is it a set amount?

It seems to be worse or sooner when it's warmed up. So my second thought is that this is one of those vehicles that has two tempature sending units one for the gauge and one for the ECM. Would keeping it in a cold loop cause this? Although I haven't been able to locate a second sending unit and the book doesn't mention one.

I really appreciate the help with this guys, this thing baffles the hell out of me everytime I drive it.

McGyver

P.S. When I went to the Ford dealer to buy the friction modifier I told them which one I had and they had to get a different bottle then the one they normally sold. I told it them it was for a E4OD in a 93 F150. It was in a white bottle where the other one was in a yellow. Any thoughts on this?

 

Oh yeah checked the vacuum and lines as well. It's operating correctly. Busted off one of the boots. What was wrong with the old rubber lines? These plastic straw things suck when the get older.

McGyver