So I have a 94 f150 with a 5.0. I bought this with problems and I have been fixing it up for about a year. Last summer all of a sudden while driving it it began to run rough. Wanting to die at idle and the idle was running high then low then high at a stoplight so I took it to the shop and they put a new throttle position sensor if I remember right. Then a few weeks later while driving it again the truck was bogging down and when I smashed on the gas it would hesitate for a second then take off like a rocket. I was told that it was the egr valve and that I could just unplug it. So I did and it ran fine for a whole year until today. It started to bog down again but the egr valve is still disconnected. It will run fine one min and bog down the next. I'm stumped. Any suggestions?

Thanks!

 

Have you done any routine maintenance to the vehicle?

 

Well to be honest. I have changed the fluids. I have not given it a tune up or anything. The motor runs good. Its just this issue that has me concerned. I don't believe that its anything major. I just don't know what is causing it to do this.

 

Do you have any kid of maintenance/ service manual for this truck? The reason I ask is , if you could run the KOEO and KOER tests you might get some idea where to check. The test procedure doesn't require any elaborate test equipment. It is too complicated to describe over the internet. With a typical store manual you can run the steps and at least get some direction. In case you didn't know the KOEO and KOER stands for key on engine off and key on engine running. The engine running test is all done by the computer in the truck. All you need to do is set everything up for it to run the test for you. It will give you codes , if there are any, and you can go from there .

 

I plugged both the green and the red vacuum lines. It still runs the same as having them not plugged so I'm thinking that its not the egr valve or the sensor. I will run a test and get the codes tonight.

I really appreciate all your info and time that you have given me. Are you on here much? I'm sure I ill run into another question or 2 in the next few days.

Thanks again

 

First off, you are going to get some codes involving the EGR system since it can't function with the hoses disconnected.
The computer does a darn good job of isolating the troublesome system. When you get the codes , it will be interesting to see what they are. There are several good folks always willing to help on this site and I am only one of them when my suggestions are worthwhile! Rest assured there are some other guys that are reading these posts and are willing to add some addl info, and their comments are always welcome especially since early in the game I learned I don't know half of what I think I know!
I believe you are in good hands here and we'll wait and see what codes you get.

 

Ok so I ran the test and found out that it was the throttle position sensor. I bought one and put it in today. Man it was a pain in the but. It took me about 2 hours to take off hoses and everything to get to be able th take off the throttle body to get to the sensor. Ok so I ran a test again after I did all that and what did I do- like an idiot I started the truck and test drove it WITH the jumper wire still in the test plugs. I drove it les than a 1/4 mile and it ran horrible. It wouldn't shift so I knew something was wrong. I pulled in my driveway and parked it and shut it. Off. I opened the hood and the first thing I seen was that jumper wire- I was so mad. Anyways noy the truck won't start. I don't hear the fuel pump or I can't change from one fuel tank to the next. I'm affraid I may have fried something- any idea?

 

A good start would be to check ALL the fuses. I have never come across the problem of having driven the vehicle with the jumper in place. If you can't find anything specific , try disconnecting a battery cable for a few minutes and see if that allows the ECM to start from scratch. They will reprogram themselves after disconnecting power to the ECM. All I can suggest is, it's worth a try.

 

So I dodged a bullet! I traced the problem back to a faulted tps from the parts store. So I replaced it again. It runs pretty good now but it still bogges down a little. So I'm gonna try a new map sensor. It is narrowed down to a fuel/air mixture issue. So hopefully today will bring a solution

 

Ok so the problem has gotten better. I have tested all the sensors and they are all good. I'm not getting any new codes and the problem is still there. It is a lot better but still there. I changed the fuel filter and put some sea foam in the tank. Every once and a while when it boggs down and I mash the gas it will backfire out of the manifold then take off. I'm at a total loss now and have no idea what else it could be.... Any ides or suggestions?