CFI Computer

[MattsLincoln]

does the CFI cars have a computer that controls the CFI unit. i was wondering if it does if i replace it with a new one if that would fix the rest of my hesitation problems. There is an 1985 Crown vic at my local junkyard that has cfi and i was wondering if i could use that computer.

[Lincolnmania]

the 85 is eec IV.........your 83 is eec III.......it will not work......i highly doubt the ecm is your problem

[gadget73]

What he said. 83 is a totally different animal. The computer is usually not the problem when the car won't run right. Once in a while they fuck up but 95% of the time, its something else. EEc3 has extremely limited diagnostic abilities, so basically you have to start testing stuff. Probably the best thing you can do is get the shop manuals that explain how that mess is supposed to work, and how to test things on it.

[pstrbrc]

the '83 cfi computer is different from the '84-'85 computer. Which means that the '85 probably won't plug into your car. But it's unlikely that your computer is only "kind of bad", anyway. Most electronic units are "it works/it doesn't work" with no "kind of" in between. However, there's a whole host of components that can go bad. And if any one of these are bad, a new "brain" wouldn't help. Now, these observations are just based on the 5 cfi units I have scrounged for "research", and one complete system (my car!).
#1. Injectors. Man, these things are all over 25 years old, and the gunk can build up! Just to see for yourself, take your air cleaner top off, start the car, and shine a flashlight down the throttle throat, and look at the injector stream. Pathetic. And the dribble coming from each injector will probably be rather different. Clean, they should look like a nice fine spray. Here's how I cleaned out my 10. I tossed them all in a coffee can of gas with an extra dash of acetone for a week. Probably didn't need to be that long, that's just how long it took to get back to them. Then I patched an extra injector connector, a switch, and a battery together so I could activate a single injector. Took each injector out of the gas, plugged it in, switched it on, took an air hose and blew everything out. Put two into my car. Major difference, especially at idle and just off idle.
#2. Throttle position sensor. On the opposite side of the throttle shaft from the linkages for the throttle pedal, transmission rod, and cruise control. Black plastic thing with three wires coming off of it. This is a variable resistor (potentiometer) that tells the computer how far open the throttle is. Of the six I have three are crap. They do not produce anything close to a linear output. It's easy to test one of these if you have a $10 analog multimeter. (WalMart sells 'em) Unplug the tps, plug the leads of the multimeter into any two of the terminals in the plug, set it on The horseshoe shaped icon, and move the throttle open and closed. The needle should move smoothly through the range. If the needle barely moves, pick a different scale. If the needle movement uses up the whole range, but moves jerkily through the range as you move the throttle, it's bad. If nothing happens, you picked the two terminals that don't do anything! Just pick another two terminal combination. In fact, you will want to test all three terminal combinations. One combination should show a constant resistance. One combination should go from no resistance to full resistance when you open the throttle, and one should go from full resistance to no resistance.
#3. Fuel pump/fuel filter. Your fuel pump is 28 years old, for pete's sake. Low fuel pressure can do this. Start the car. Take a tire gauge (yeah this isn't exactly recommended, so have a fire extinguisher handy) and rev the engine up to a fast idle. Check the pressure at the schrader valve on top of the throttle body. If you do it firmly and with a steady hand, you won't make a mess. It should read 30#. If it doesn't, replace the fuel filter, if it still doesn't fuel pump.
#4. Vacuum lines, especially to the Manifold Absolute Pressure (MAP) sensor. I think it should be on the passenger side wheel well, and it's right with the vacuum controls for the air pump system. It will be a black plasic box with a single vacuum line going to the base of the throttle body, and a three wire connector. I think it's 7/32" vacuum line, 30" long, just replace it. In fact, do this first and see if it helps.

In fact, now that I look at my list, do #4 first. Then #2. If the tps checks out, come back and holler, and I'll take some pics and post them to show you how to get to and clean the injectors. OK?

[MattsLincoln]

any body have a CFI vacuum hose routing diagram. And pics of these hoses.