Hi, I bought a 93 ford crewcab that was abused by the poor owner's sons. So after finding all the cut vacuum lines, unplugged sensors, etc..the check engine light was on, indicating that it was a bad TPS with low voltage. So, I replaced the TPS with a new one (I have the non-adjustable type), the check engine light was still on and was indicating the same thing. I unplugged the ground for five minutes and still did the same thing. It runs rough and dies when the tranny is engaged. So I talked to a local shop who said that the computer could be bad. So since I couldn't find the computer where my chiltons suggested (behind the passenger side panel) I was told by another to look behind the glove box. So I found a small and large box of sorts and thought that maybe these were them, so I unplugged them and took them to my parents house to check out a parts truck I have in the same year and engine, tranny, etc. I was going to swap them and see if that would solve the problem. Well later I found the real computer, took it from the parts truck and plugged that computer, along with the two original boxes behind the glove box and tried to start and the truck won't start. Then I tried to plug it back into the original computer and it still wont start. After thinking about it, I realized that I didn't disconnect the battery when I did this. Could I have fried the computer, or something else? Does anyone have any suggestions? Is there still hope?: Any help would be great. You guys have always been such a big help in the past.

 

Unplugging the the computer with the battery hooked up should not have taken the computer out. I have done this many times with no problems.
While the computer is out open it up and see if you see anything burned up.

Leave the computer out or unplugged and try to start it on starting fluid.
If it starts you you may have a computer problem.
If it will not start then you have a Ignition problem.

 

Uhm... if he unplugs the computer, the injectors won't open, and it won't start anyway...

As for the problem- first I'd start double checking sensors. The procedures should be in your chiltons. If it runs rough and dies ONLY when the tranny is engaged it's either an electrical problem [bad ground or sensor] or the tranny is shot, which could be if it was abused by the PO.

If you have enough jackstands, or even bricks and blocks, get all 4 wheels off the ground, put it in gear, and see if it will run. If it does, then it will only die under load. From here you can start with the basics- air, fuel, spark. Did you replace the air filter? Is it getting proper fuel pressure? Is it getting spark and if so, is weak/hot, etc?

Keep us updated.

 

Pretty sure that's what the starting fluid is for.

 

...Okay, in all fairness, I'm really tired right now. At first I was going to argue your point that even if he's using starter fluid, that still won't work. Somehow in my thought tank I wasn't thinking about the fact that starter fluid is sprayed thru the air intake!