It goes between the main harness and the computer. All other sensor plugs remain the same, just 6 new injector plugs and mass air plug are added with the overlay harness.

 

my injector harnes has all 8 injector plugs, i didnt reuse any of my old injector plugs. i pulled KOEO test codes and am getting 85 and 95 85= canister purge valve,,,,95= fault in secondary fuel pump circuit. I know the fuel pump circuit is fine cause the truck runs great, it just idles rough, especially in gear and when cold, i wonder if i should try bumping my timing up a little (have 93 octane in the tank)? i know most of the sensors are under 2yrs old....including the iac and the tps...and i didnt have any idle problems before the new pcm was installed....will get my bro-in-laws timing gun and check timing today....and will keep posted....thanks

one thing i forgot to mention...about a year ago i was suckered into that little resistor they sell on ebay that you bypass your iat with and trick your pcm into thinking its cold at all times. it didnt affect driveability good or bad with the old pcm, but i wonder if it could be messing with my new computer? just another thought, i need to just replace that sensor and hook it back up

 

I think Eric ment to say 8 instead of 6.

The computer has a 60 pin connector on it for a wire harness plug. The MAF kit sandwiches inbetween the computer, and the truck's 60 pin connector. It has 8 injector wires and a MAF wire on it. The kit basically re-wires the setup vs doing it manually. They give you little plugs to put in the original injector connectors as they are not used.

If you didn't get code 85 before, but you're getting code 85 now...it could be because the MAF kit isn't letting the CANP signal pass through the connector to the computer and the computer isn't getting a signal. I found that out when I was working with it. I havn't gotten to a solution yet, been on the backburner. That soleniod is energized when the ECA decides to (usually during part throttle cruise) vent the fuel vapors stored in the charcoal cansiter into the engine to be burned. The solution is to find a way to get the pin to go through the connector, one of these days I'm going to call Ford Racing and ask them about it to see what they have to say.

 

I was thinking that two of the original injector wires were used, but I guess I didn't see things correctly in the picture Ford puts out. I trust what you guys say more than the picture in the item description.

Code 85 won't affect driveability at all, so don't worry about it too much. If there is an electronic purge valve that isn't getting used, I'd just take it out and let the line run straight to the throttle body. My truck didn't have any kind of purge valve stock, so it won't hurt anything. Code 95 is probably because of the stock truck wiring. The mustang ECU monitors the output from the fuel pump relay to the fuel pump, while many of the trucks did not monitor this voltage. I wouldn't worry about that code either. As long as the fuel pumps are running, there's likely nothing wrong.

 

Yours doesn't have one? My 89 does and my 95 does. Interesting.

 

what do you all think about the timing, cant i advance it a couple of degrees and gain more power? i think im gunna run 93 octane all the time cause im gunna have a chip burned for it anyway

 

The chip will sometimes change the timing depending on what you get. Base timing stock is 10 degrees, you could move it up to 12 or 14...run 93 in it and advance the timing a little bit at a time until it pings under load - then back it off a degree or two. You just have to keep in mind that you're running closer to the edge of pinging and on a hot day or towing a load - you'll have to remember to be careful and listen for pinging. If an engine pings for a long enough period of time (doesn't take much) it'll destroy the engine.

I would say don't bother with a chip - they arn't worth much on these. Just advance the timing a little and have at it.

 

well thats what i was thinking, why not just advance the timing myself, but i keep reading about how ford runs engines rich to keep the cat cool. since my cat is long gone (non emissions state) i was thinking the engine could be leaned out some, and i dont know how on efi to lean it out without getting a chip. also would advancing my timing help my idle problem? thanks

 

The idle problem is not to be fixed by timing - first thing I'd do is take the IAC off and clean it out. You also have to make sure your TPS voltage is right.

I'd just leave the computer programming alone. You're not going to pick up much power by playing with the A/F ratios on a stocker. It's within reason and playing with the timing is probably what you should do.

 

I converted my 89 F150/5.0 about two years ago. Rescently I had to pull the codes for a little "icing" problem I had and for the first time I pulled an "85". Looking through the code book, it said it could be either the Canister purge solenoid or the computer has reached it's limit toward the lean side. Looking through the Haynes manual, it say's that only the 351's came with canister purge solenoid's. Any know the real answer on this? If you have a 5.0 and you get a code 85, is it the purge solenoid or the "lean" limit? The reason I say this is in two years of running the FMS MAF conversion, I never got a code 85 until rescently.

 

I havn't read anything about code 85 relating to anything other than the CANP solenoid. And the 302's had CANP solenoids too - so whatever you're looking at isn't right...

 

I got the information on the code 85 from the actual manual that came with the code reader. I agree, it is the only place I have seen give another option for the 85. It may not even relate to the F-150. However, looking through the Haynes maual again, it states that all EFI models came with a canister purge solenoid. Yet if you look at the wiring diagram for 87-89 F-150, it states that only 5.8L and 7.5L have the connection? Weird. Mustang, where is yours located on your 89? I might be missing something.

 

The CANP is always in the same general location - in a vacuum line between the charcoal canister and throttle body...

The general wiring is the same on 87-96's...the sensors are all the same and in the same locations, but the older trucks have a different connector that goes to the main wiring harness. The engine wiring harness will disconnect from the truck's chassis harness. The older ones have 4 plugs where as the newer harnesses have just one bigger square plug. Both plugs are on the drivers side inner fender. The other difference is the TFI modules, the older ones are on the distributor and the newer ones have the TFI module out of the engine's wiring harness and in the chassis harness. The TFI module is bolted to the drivers side fender near the hood spring.

I'd be willing to bet that your code 85 is the same reason I'm getting it, the conv kit isn't letting the signal pass through the connector to the computer...and the computer isn't seeing any signal as if the CANP is disconnected.

In my case, I also had to do a little wiring adjustments with the O2 sensor, and switch the o2 sensor to a mustang one (3 wire) vs the truck's 4 wire. The computer wasn't seeing a o2 sensor signal.

 

quick question, when the engine starts and its cold you stated that it ran in the low rpm's, did the 'check engine' light show up on the dash?
mine did that after I replaced the iac module...it wasnt oem but was purchased from napa...once the engine has been running for approx 45 sec, it revs up and then the 'check engine' light goes off, I also noticed that it whistles when the engine light goes off...
any idea?

 

You can check the computer codes and find out what code the computer is giving you - whether or not it's IAC related. Do a search in the 87-96 forum for "checking computer codes" or similar combinations of keywords - u'll pull up threads on how to do so.