On our recent conversions to a 5.0 Fuel Injection in a Maverick and Comet we found the best SpeedoCable for this work to be a 83-88 FORD RANGER ATP Part Number is # Y-851 . After attaching to the road speed sensor it comes out ONE INCH LONGER than the factory setup. This avoids having to have a Custom Cable Made . This applies to MASS AIR conversions ONLY ..Speed Density does NOT need a Road Speed Sensor . Hope this helps. Dr.Bill Cometized Chip
Chip, I have a question that is somewhat on the same topic. I thought you might know. I used the Ford racing harness that omits the neutral sensor and the speed sensor inputs to the computer. So, my engine only has an in drive idle speed and gets no data for throttle closed vehicle in motion. I'm considering adding these circuits. Do you know if the voltage going to the speed sensor is 12v or 5v? I don't know how it is supplied. Whether it is from the battery or from the computer like the TPS. I believe the neutral is 12v since it directly powers the reverse lights. Thanks, Micah
Hello Micah: The following information is gleaned again from Bill Roberts here at C.A.M.E.O. .. He has performed complete rewiring of several cars over the years and has responded to your question to me . Here it is ; The speed sensor does NOT use +12V or +5V as it is a small AC generator . It simply connects to pin 3 and pin 6 of the ECM plug . Pin 3 is the dark Green & White Wire , and Pin 6 is the Orange & Yellow Wire . As an AC generator, it creates a AC output proportional to road speed in both frequency and voltage. Because the voltage can be high at high road speed, I would not run the wires adjacent to the O2 wires (very low voltage in the O2 wires) as it might cause interference. For the neutral switch, do you have an automatic or manual ? Also which computer are you using , A9L , A9P or A9M ?? If you let us know WHICH you are running we can expand on the solution. Under NO CIRCUMSTANCES apply +12V to Pin 30 , the neutral input pin or it will FRY the computer !! We'll get back to you when you reply. If you wish to contact me directly the email address is cameocarclub@yahoo.com .Incidentally, what YEAR is your car because it matters ?? Cometized (Chip)
Chip and Bill, Thanks very much. I would have never suspected that the speed sensor was a little generator. It makes perfect sense that it is. I'm currently running an A9P. I had it chipped with an SCT unit but I'm going to dump that and go to a Moats Quartehorse so that I can data log. Idle issues have been plaguing me. I have an AOD in the car and use the built in switch for the neutral safety and back up lights. I have an OEM floor shifter that makes no connection to the steering column. The Ford Racing harness does not have any wires coming out of these locations. I will have to see what I can do to insert them into the main plug. Here is the rundown on the full specs on my car: http://mmb.maverick.to/resources/my-1971-maverick.221/ I'll keep the post here in case some others are interested in the info too. Thanks, Micah
The neutral safety section of switch just routes 12v to activate solenoid, doesn't carry much current, the backup light section no doubt has to handle a heavier load... I converted a '86 Stang to mass air and never used the speed sensor(didn't have cruse so didn't have one), have heard can cause stalling but mine was fine... There was one already on T-Bird when I did 5.0 swap, that one is connected... This is how the speed sensor output looks on a scope, took this back in '09 as we were discussing it over on T-Bird board... I was spinning it with a variable speed drill...
When pin 30 is grounded, the ECM see this as the transmission being in neutral. On a stick this is straightforward...the transmission switch and the clutch switch have pin 30 connected to one side of them and the signal return (ECM ground) connected to the other. When either switch is closed, the ECM knows the engine it not connected to the rear wheels. With an automatic things are a little different. The only neutral switch is also used by the started solenoid to prevent the car from starting in gear (the clutch switch on a stick has a separate set of contacts to do this). So what they do is tie pin 30 to the wire going from the ignition switch to the neutral safety switch, When the car is running, there is no power coming from the ignition (only when in the start position) so when the car is in neutral or park, pin 30 is connected to the starter solenoid through the neutral switch . Since this part of the solenoid is only a coil of wires with the other end connected to ground, the ECM see ground through the neutral switch and then the solenoid and knows that the transmission is in park or neutral. Remember I said don't apply +12v to pin 30...well that's only for the A9L (the standard transmission ECM). the A9M and A9P (the automatic transmission ECM's) have an internal diode to block the +12v so they will not be damaged when the key is turned to "start" and +12v is applied to pin 30 while the car is cranking. I will draw and post a schematic for this tomorrow. Wow, looks like the Ford Racing Harness is missing some stuff. Does it have AC monitor (gives an idle bump when the AC is on) and AC cutout (turns the compressor off at WOT to save some power and save the compressor from high RPM)? I have always made my own harness out of a 5,0 Mustang harness so I never had to deal with anything being omitted. You said you are having idle problems...have you adjusted your throttle blade position? I can help you with this if you haven't. Hope this helps.
Chip & Bill, I had hear about the issues of using a manual computer in an automatic car. Now I understand why. It seems easy enough for me to tap in to the switched side of the neutral safety switch. There is already a wire going to the computer for the start function. I don't know why they omitted this function. The harness does monitor the AC and allows for the appropriate inputs to the computer. I have played around a lot with the idle issues. I think my mass air meter may be too big for the engine output. I'm going to a Ford Lightning unit. Also, my tuner had no ability to data log. So I'm dumping him and going to the Quarterhorse with the data logging software. I wont be able to play with the car for a few more weeks. It has a preliminary tune installed. I plan to get it to the dyno and do some additional WOT work and street tune from there. Micah
Just to make it clear, you need to tap pin 30 into the wire leading from the key (ignition switch) to the neutral safety switch....not the wire from the neutral safety switch to the stater solenoid. I would also insert diode into the wire going to pin 30 to block +12 volts when starting...just for safety...there is no down side to using a diode... plus, you would be able to use an A9L in the future if necessary. I am about to wire an automatic (C4 ) with an A9L (because I have it, and it will work just fine) in a 72 Maverick with a 347 stroker, so I too will be using a diode. I may have a few suggestions about your idle problems...I will review your specs and post back. BTW I scanned your build link (and will be reading it more in depth) and you have done a a very nice job...awesome car. ...Bill
Thanks Bill, That makes sense. If I did it after the switch, it would read neutral all the time. I know you are repurposing old harness, but do you know how do you get a pin into the main harness plug? Mine is blank. Micah
Sure, I rework the factory harness and delete things I don't want before installing it. From the computer side of the plug. pry out the red insert with a small screwdriver. Then, if you look down inside the plug you will see small plastic fingers that hold the wires in place. To remove a wire, pry back the plastic finger away from the wire and pull the wire from the other side of the plug. To add a wire simply push in in from the non computer side of the plug. and it will snap in place. When you are done, reinsert the red insert
