computer troubles
03-09-2014, 09:09 AM
#1
computer troubles
I bought my F-150 XLT Lariat new in 1992. Within the first few weeks I got a check engine light. I took it to the dealership four times and the mechanic seemed lost. On my last trip I, I found him with his head on his arms under the hood shaking his head back and forth in obvious misery. I walked up and asked him how it was going. He said that he had checked everything, but could not find anything wrong. I had no specific experience with vehicle electronics, but I asked him what the computer said was wrong. He said that it said it was running lean and he had tested every sensor and all checked good. I then asked him if he verified the it at the tailpipe and he said yes and it checked good, so I said it sounds like you have verified your inputs, but you are getting a bad output. His face started to darken especially when I said that on any computer if the inputs are good and the outputs bad (black box troubleshooting) then the computer is at fault. He said that he had to have all his ducks in a row before he changed the computer. I suggested he call his hotline and see what they had to say, which he did and then replaced the computer.
Although the truck has been parts hungry and breakdown prone for years, the computer lasted until about five years ago. I determined that it was bad and changed it. Instead of getting the number off of the label on the computer, I foolishly had Advance auto look it up. The computer has done okay until recently, but as I've read codes off of it over the years, I've noticed it sometimes complains that the transmission is not in park. I have a standard transmission. It now tries to say that the coolant is both too hot and too cold. It says the egr valve is bad, but I replaced it and it still says it's bad. The check engine light works at start up but doesn't come on for a fault. I'm going to pull the computer and test the solenoid for the egr as well as all other loads. I need to know what the original computer number was, since I suspect that I bought the wrong one. There are 7+ listed on various sites for a Ford 1992 XLT Lariat with the standard tranny and 4.9l six. Probably only one is the right one. The prices vary between the models and based on my experience with the truck, the most expensive one is probably it. By the way does anyone know if there is a new aftermarket replacement for this computer, since it has a rather bad rep?
If anyone knows how to select a computer for this truck without knowing the original number and if anyone knows if there is a aftermarket replacement for it, please let me know. Thanks, Don Baker
p.s. I also have a '99 Taurus which has more miles on it than the truck, but I've had remarkably few problems with it and it still runs like a new car. By far and away the best vehicle I've ever owned. I think I just got unlucky and bought the wrong year of truck.
Although the truck has been parts hungry and breakdown prone for years, the computer lasted until about five years ago. I determined that it was bad and changed it. Instead of getting the number off of the label on the computer, I foolishly had Advance auto look it up. The computer has done okay until recently, but as I've read codes off of it over the years, I've noticed it sometimes complains that the transmission is not in park. I have a standard transmission. It now tries to say that the coolant is both too hot and too cold. It says the egr valve is bad, but I replaced it and it still says it's bad. The check engine light works at start up but doesn't come on for a fault. I'm going to pull the computer and test the solenoid for the egr as well as all other loads. I need to know what the original computer number was, since I suspect that I bought the wrong one. There are 7+ listed on various sites for a Ford 1992 XLT Lariat with the standard tranny and 4.9l six. Probably only one is the right one. The prices vary between the models and based on my experience with the truck, the most expensive one is probably it. By the way does anyone know if there is a new aftermarket replacement for this computer, since it has a rather bad rep?
If anyone knows how to select a computer for this truck without knowing the original number and if anyone knows if there is a aftermarket replacement for it, please let me know. Thanks, Don Baker
p.s. I also have a '99 Taurus which has more miles on it than the truck, but I've had remarkably few problems with it and it still runs like a new car. By far and away the best vehicle I've ever owned. I think I just got unlucky and bought the wrong year of truck.
03-11-2014, 09:22 AM
#2
Great job troubleshooting that.
As for your problem I say call the Ford parts counter and give them your VIN, they might be able to tell you which part # you need.
No aftermarket that I know of, unless you wanna build and configure it yourself (MegaSquirt):
http://www.megamanual.com/index.html
As for your problem I say call the Ford parts counter and give them your VIN, they might be able to tell you which part # you need.
No aftermarket that I know of, unless you wanna build and configure it yourself (MegaSquirt):
http://www.megamanual.com/index.html