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I need some guidance. My truck was leaking exhaust from the back of the engine and generally running awful. (rough idle, 5mpg, black smoke) my mechanic had me replace the EGR Tubes off the back of the engine, he replace the O2 sensor, tuned it up and it ran great for about 1500 miles. (smooth idel, 10-12 mgg, lots of power, no smoke and no smell of exhaust) I had taken it to a muffler shop after we did the work and they assured me the original exhaust was intact and they welded one small leak, all else was good.
now after about 1500 miles the symptons of exhaust smell, bad idle and awful gas milege (90 miles for about 20 gallons)
Now my mechanic tells me that this year modle has computer issues and that most likely the comp. is telling the truck to run like crud. He suggested either replacing the computer than retuning, or putting a piggy back computer on the old computer to straigten out the codes then retunning.
Has anyone heard of this, dose it sound reasonable and are there any suggested courses of action I might take to help do the correct thing?
I've never heard of this. Is it giving any codes? I would first check the vacuum line to the map sensor. This is what tells the engine how rich to run. With no vacuum, it will run full rich.
What year is it?
It'a a 1994. I don't, personally, have the ability to pull codes off the truck. I have not had the codes pulled since it began running rough and sucking gas again. I am reading my Haynes repair manual and am liking the idea of checking the fuel pressure regulator. I will take your advice and look into the MAP as well.
any thoughts on the concept of the computer being goofy. The Mechanic stated getting a new one, or a piggy back that would translate code into the new code that is being used, and would have an in-cabin control system. something about me controling different things (I am assuming fuel pressure, air pressure, etc) from inside the truck.
it should be noted that I have all this bizarre info from my mechanic because he hasn't seen the truck yet. This is all from a phone conversation and he made these speculations based on a recent situation in which a similar 460 needed a new computer. He was able to track down, through Ford, that there had been some recalls on some trucks with this computer system and that this was the solution for another customer. I plan on having him plug it in very soon
pluggin in a computerized truck is the very first thing you should do, always.
Without that your stabbing at a mouse in the dark with a pitchfork, only the pitchfork is your wallet. take advantage of that computer, if you dont get any codes, then start stabbing away, my .02
thanks for the advice guys, I appreciate the heads up. Unfortunatley, the "check engine" light is not on, so the Auto Zone cant tell me squat. O'rielly has a piece of equipment that may do a better job. They say you can rent it and return if for no cost. sounds bizarre. I'll see what I can do and put some more info out there.
Great site with tons of help. Happy to have found it. Thanks
It means that the 02 sensor is showing that it is running too lean and the computer is compensating by richening up the mixture as much as it can. This would explain why it is running rich.
Need to figure out why it is showwing lean. Bad injector, bad 02 sensor,etc