Thanks for the response. I have never noticed the speedometer jumping around much at all. I will check the tps with the code scanner and with a meter to see what I find. I just did not know if there were any other sensors that could cause this problem. Like I said, when I first start it up, it runs and shifts fine for a mile or so then it starts this problem.

Thanks again for your help.

 

I just pulled the codes on my truck. Key on engine off: 122 (TPS voltage too low). Key on engine running: 122, 998 (Engine control system operating in Failure mode and effects management (FMEM) programming strategy. Now what's up with that?

I was hoping I would fine a tps problem because thats would seem to make sense. But I have no idea what this 998 is. Any thoughts?

Thanks for all of your help.

 

Well the feed back I have seen on here is that Ford dealers always says that a 998 means that you need a new computer.

 

I found one web site that sid it meant I have a "hard fault". It said if the computer detects a serious failure of one of the sensors, it will throw this code and run the engine on a "base" number just so it can be driven. The web site said it usually is accompanied by another code or two. Since the only other code I got was the tps, I just purchased a new tps from napa and am installing right now.

 

Well the tps did not fix it. The transmission seems to not be able to decide what gear to be in at low speeds. And it will jerk so bad, I am afraid of throwing a u-joint. I will drive like a brand new truck for a few miles then all of a sudden it starts this crap. It also seemed like the tranny was slipping some of the time. And if I put it in OD it would shift back and forth about every 1 second. I just spent $2400 on a rebuilt tranny about 18K ago. I am just about through with this truck. I think it is a lemon.

If the tranny was having problems, would it give codes or not?

Any help would be appreciated.

 

They claim the computers are tough and will out last the truck many times over but from what you posted I think I'd try a different one to be sure.

And yes it would, or should through codes for the tranny.

The speedo head could also cause the problem of what you state here,

<i>The transmission seems to not be able to decide what gear to be in at low speeds. And it will jerk so bad, I am afraid of throwing a u-joint. I will drive like a brand new truck for a few miles then all of a sudden it starts this crap. It also seemed like the tranny was slipping some of the time. And if I put it in OD it would shift back and forth about every 1 second</i>

I got no codes when my speedo head was bad, it jumped in and out of gear, had the "lost drive" issue and would not hold TCC lock up until I changed it.

I guess the computer though it was doing what it was supposed to do based on information it received. I seriously doubt its smart enough to know the difference between the correct amount of speed changes and shifting that should happen to a bunch of crazy fast varying speeds/shifts well beyond what the truck is actually capable of. It just goes on the information given it and shifts accordingly regardless of how wrong that may be. It receives it and reacts to it so no code is given.

The "Programmable speedometer/odometer module" (PSOM) is in the speedo head/gauge assy.

 

Are you saying what might be the problem is in the cab behind the gauge cluster or down on the tranny? I did see a large bundle of wires going to the passenger side of the tranny but it was too hot to inspect at the time.

If I have to send the computer back just too find out there is nothing wrong with it, I sure it would be costly and be an ordeal. The truck was acting kind of like this before my computer fried. It is just worse now. Before, I was still able to drive it but now it is un-driveable. I don't know if I should take it to a transmission shop or to the dealer.

 

The "Programmable speedometer/odometer module" (PSOM) behind the gauge cluster for the shifting problems might be the cause. Not saying it is for sure but it is something that could cause the problems.

You had a fried computer to start with, burnt to a crisp. Did you ever find anything that could have caused it?
Whatever caused the first computer to fry may be the problem now. May not have anything to do with the PSOM but giving it the similar/same symptoms.

I'd be awful leary of running it on the replacement computer until I was sure there is no wire pinched, wore through, no sensor grounding out a pin that's not supposed to or anything that could damage the computer again.

The kinda crazy stuff you say happens, the codes you get and or the lack of them, the way the truck runs and drives would suggest you have a wiring issue of some kind someplace and its wreaking havoc with the computer and in turn the tranny. All of which rely on a steady supply of power to function normally.

Bringing it to a Ford dealer is a waste of time, big bill with no results. They couldn't find a problem with one of these trucks if it jumped up and hit em right on the forehead.

Oh and a tranny shop would likely want to tear down the tranny and rebuild it, I doubt you need that done. At least not at this point.

 

<i>Well I just recieved and installed my rebuilt ecu from autocomputerexchange.com. The truck started right up and idled smooth and relatively low (700 rpm or so). I drive it for about a mile or so then it starts. The same problem I was having before, shifting real hard. While it was idling in front of my house, it abrutly jerks as if the computer just reset something then it starts idling higher (1100 rpm or so). When I put it in gear it instantly engages with a big clunk. As I drive it changes gears very soon and jerks each time. The only difference with the new computer is that it seems to lobe along after changing to second gear. Once it even seemed like it jumped from first to third because I pulled up a steep hill and it just about would not go because it was lugging. I have not pulled codes yet because I simply have not had time to do anything. I had the transmission completley rebuilt about 18K miles ago.</i>

Based on your comments here and the fact the new computer hasn't gone up in smoke yet you could pick up a gauge cluster at the bone yard and see if it helps. One should run 35 bucks or so. Make sure yours, the one in your truck now, and the one you buy at the bone yard (if you do, I'll leave that for you to decide) are kept upright at all times. edit; You can tip it to get it out, just return it to the upright position once out and keep it that way.

I also note you said you looked for burnt wires under the dash, you did also look under the hood and under the truck too? You looked over all the wires everywhere right?

 

Okay my turn for some useless suggestions.
1. Disconnect the negative terminal on the battery wait a minute and reconnect.
2. Let idle for about 15 minutes and turn off if engine still idle smoothly.
3.Check eec for codes. If there are codes, fix them. If not, take it for a run.
4. if it works fine, recheck for codes. should be none.
5. If it doesn't work fine, then I would suspect the EEC. Just because it's new doesn't necessarily mean it's good.

 

Okay I have an update.

The speedometer never jumps around at all. It constantly provides the correct speed smoothly. I have looked at every wire harness on the whole truck for something obvious with no luck. I removed the connectors for the vss (if that is what it is called that is on top of the rear end), and both connectors on the tranny (the driver side one on the manual shift and the large one on the passenger side) and inspected the connectors and smeared dielectric grease on them. After the truck has not run for approx 2 hrs, I started it up for another drive. It immediately ran with higher rpms and jerked around with the shifts.

If I put the shift lever in 1st, the tranny slips when I give it some gas (as if the torque convertor is not locking up). When I put it in 2nd, it stays in second only but does not slip when giving throttle. When I put it in 3rd, it slams in gear and jumps around and slips some of the time. Its running too bad to get back out on the highway to try overdrive again.

I just don't want to throw parts at it unnecessarily, but if it sounds like it may be the psom then I will head off to the junk yard.

I really do appreciate all the help I have received. Thanks.

 

All I can say further at this point is my speedo needle was rock steady.

I wouldn't replace it and continued to look elsewhere for the cause of the problems because of that one fact. Everything I read said the needle would be erratic if the PSOM or VSS was bad.
I finally said to heck with it and replaced it in the hope it was it, it did correct most of the problems I was having.
I have a TCC lock up issue still, I put in a Auto/off/On switch and a light that glows when the computer gives the command to lock it. That way I can run with it locked and see when and if the computer does. The computer does about half the time. I contribute that small issue left over to the replacement cluster. It has 170k on it and is a loaner from the bone yard. It is from a truck with a manual transmission, they will notify me when they get one in for a auto, and one with a tach.
My truck has 94K on it by comparison so one with 170K is on borrowed time I'd think if mine was bad.
For now I just lock the TCC clutch myself when needed. I know its not the tranny, it locks and stays locked as long as I have the switch in the On position and never drops out. The indicator light I rigged up works regardless of switch position so I can watch what it is doing.

 

I forgot to mention that after replacing the tps, I am still getting code 112 with engine off and 998, 112 with the engine running. The first tps I bought several months ago was from Advance Auto. This time I went to NAPA and they had two different ones. The cheap one for $40ish and the better one for $70ish. I went ahead and bought the more expensive one because of the possible problem with the first tps. But now, after replacing it, it does not seem be have been the problem.

What keeps getting me confused is, when I reset the computer (disconnecting the negative battery), it will run perfect for a few miles. It seems to me that if I had a grounded wire or something like that, it would run like crap all the time even after resetting the computer.

One thing I will try tomorrow is getting it hot when it is running bad and resetting the computer then to see what happens.

Thanks for all your help.

 

By the way the code 112 code in 1992 is for the ACT not the TPS.

 

<i>What keeps getting me confused is, when I reset the computer (disconnecting the negative battery), it will run perfect for a few miles. It seems to me that if I had a grounded wire or something like that, it would run like crap all the time even after resetting the computer.</i>

Well yes and no but what that does show is once the computer takes over it starts screwing up. It runs open loop until it gets up to running temp, then goes closed loop and the computer takes over. So at that point if there was a wiring problem that effected the computer it would happen then, where as is it wouldn't when it was cold and the computer hadn't taken over yet.

Look at the tables, see the sensors that take effect once it goes closed loop, one, or more or them should be your problem. Scroll down this page and you will find a chart showing what does what at what point, closed loop verses open loop.

Ford Fuel Injection EEC Computers