I thought of something you might try.
Thinking that an injector is sticking open longer than it should but stays closed when doing the WOT(wide open throttle) test.
Unplug 1 injector, start engine, yes it will miss but see if it is still blowing black smoke.
If so shut off engine and plug injector back in and then unplug the next injector, and so on.
If black smoke stops then the unplugged injector was the one sticking, replace it
Fuel injectors have a spring that pushes it closed after opening, fuel pressure also helps, but if the spring breaks injector can lag in closing time.
Well RonD i'm totally lost got the other computer back, did the same thing rpms go almost double engine revs up have to turn it off. All i did is take the old computer out that had a burnt diode, is there something missing? How could this be such a nightmare. I unplug computer & put other one in what else could this be. Im so upset im retired, disabled it takes a lot out of me to do anything RonD. I need spine & back surgery it takes me 3-4 hours in the morning to even move. Any suggestions besides tking in to a ford garage. Thanks Art
Well RonD IF I DID this and i have to just feather it too keep it running that would be a sign to replace it correct? Now once i get this truck running should i take it to ford to double check to figure out why the computer burned up, or should i just figure that the mechanic that rebuilt it didn't tighten the intake causing everything to go crazy? Thanks Again RonD WILL KEEP U POSTED Thank Art
The computer is suppose to open the IAC valve all the way for starting, when engine RPMs get above 500(engine started), it will then start closing it to set idle.
When IAC Valve is without power it will be closed all the way, so if unplugged when you start engine RPMs should not go up, if they do then IAC Valve is stuck wide open, that can happen just from being dirty, valve can't slide, it can be cleaned.
You can remove the IAC valve and check it first, see if it is stuck open.
If not hook it up to its wires while it is off and turn on the key, it should open all the way,
Then turn off the key, it should close all they way, repeat a few times to make sure it isn't sticking.
IAC Valve uses a Step Motor, Stepper Motor, these motors have "step" commands that are called on by voltage pulses, like a Morse Code.
They usually have 100 or more "steps", each "step" tells the motor to turn a few degrees, but they are fixed "steps"
Step 25 could mean turn 90deg from 0(valve closed)
Step 50 might mean turn 360deg from 0
Step 20 might mean turn 60deg from 0
Each "step" means turn X number of degrees from a known point, in this case 0, and each step opens or closes the valve.
Computer can send Step 80 command and then Step 10 command, motors current position is not relevant to the next Step/command.
The computer learns which "steps" set what RPM on the engine.
Computer learns that Step 22 sets engine RPM at 653RPMs when engine is warm(target is 650)
If you get a small vacuum leak so RPMs increase it will learn that Step 22 is no longer setting RPM at 653, it will try step 20 to get back as close as it can to 650
So it is adaptive
Ok RonD it wont move i even took it apart plunger moves by hand but solenoid wont budge. I even left key on un plugged it & plugged it in never moved so this could possible be it. Even turning key on & off it didnt do anything. Thank god the company who messed this up is paying for all of this. I will keep u informed by the way ford wont work on this they said its too old i found a shop that has a ob1 scope but thats last results. Thanks Art
RonD well i know the computer is bad that diode was burnt on one side, the plastis under was also burnt, with the iac not working or froze up my quess is the iac. I will replace it in a few days once i get the part & keep u informed thanks RonD Art
Well RonD sorry i've been not well, I did replace the IAC, still same problem. Since THE COMPANY that messed my truck up is paying for everything having it towed to a shop on monday. I also noticed a leak under truck on passengers side on the pavement so it might of done more damage than i'm aware of. I WILL keep u updated just very upset that the place I retired from has gone down hill and screwed my truck up. Thanks Art
Well RonD BIG PROBLEM!! Ford tells me they wont work on it that its too old in which i think is a crock of ??.,/l/ Anyhow the 2 garages said they would until i told them who messed it up, they wont touch it so now im stuck. im online trying to find someone to work on it, trust me the company will pay at any cost to get my truck fixed so if you know anyone besides Dixon Auto Repair in moraine , ohio & Rons Bp in miamisburg, ohio these two shops wont touch it so im back to phase 1 at least they are renting me a car but its not mine. Still searching for someone any ideas in dayton area or within 100 miles of west carrollton please let me know Thanks RonD Art
Art, I am sorry to hear that your problem is not solved.
That is the kind of problem I like to troubleshoot. I would start over, and carefully troubleshoot the operation
of the injectors, and go from there. As Ron says, this is clearly a fuel/air ratio problem.
Listening to the injectors pulse with a stethoscope is a good way of telling by ear how they are working.
I have listened to the sound of injectors, and have a good idea of what they should sound like.
When I have some time I plan on watching the waveform on a scope.
I hope you can find someone near you who is good at real troubleshooting and testing who could help you.
RonD I did find a shop down the street the company that messed the truck up pays for everything. This guy majors on porsche, bmw but works on fords & chevies. He feels he can fix it. So RonD I Will keep u informed. Hes booked until 27th but thats fine they are paying for a rental for me. RonD i will keep u informed thanks Art
Well RonD the shop smoke the engine & everything only $289 including tax found the problem. The vacum to the cruise control caused the high idol, the cruise was not working so i told them instead of fixing it just unhook it, they found other vacum lines not hooked up properly so its all fixed thanks so much for your help. The computer was bad causing it to blow out black smoke & eat gas like crazy. Now i get the truck back & i can finish it i will try to post a pick of it. Next project after i recover surgery getting a travel trailer and finish my retirement. Thanks so much you are the best. Art