Huge Problem: Maf Conversion

Copied From bbunt302

Just for reference, here's a list of all the compatible years:

89 harness should work for 86-89 as long as you're using mass air.
90 harness will only work in a 90. (B/c of air bags and dual dash connectors)
91 through early 92 harnesses should be compatible (single dash connector, fuel pump relay under driver's seat)
Late 92 through 93 harnesses should be compatible (single dash connector, fuel pump relay under the hood)

Computers from 89-92 are all the same. Look for the A9L sticker on the back cover for a 5 speed that matches your requirements. Example: E9ZF 12A650 AA" with the A9L code.

AutoZone wiring diagrams

http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model cars

I didn't check those diagram links, but just
in case -

I've always had good luck getting very complete
diagrams in the big motor manuals at the local
library, and they'll usually let you photo copy
out of them right there for cheap.

I don't know how complete those AZ diagrams are, they may be great. Just in case -

I've had good luck finding very complete diagrams in the big motor manuals at the local library, and they usually let you photocopy out of them right there for cheap.

You shouldnt of had to change out the entire engine harness. Just add in the section that goes to the MAF. Like 4 wires.

yea its only 4 pain in the ass wires, and a new computer- if u plugged that harness into yoru old computer, there no way it will work

I had to hard wire my fuel pump relay. After doing that it worked fine.

too late now, but you shoulda just added the 4 wires

I'd put the original harness back, then add the 4 wires and MAF

sorry to hear you already put in thew new harness man, the maf harness sucks to install, but it should be a walk in the park for you now, w/ all the wiring you did!

which injectors

Which injectors do you have?

I think the speed density injectors are different from the mass air injectors in relation to amount of fuel.

I have NEW grey top injectors off of an '86 5.0 H.O. which are 140cc @ 3bar that I was hoping to replace my OLD '92 5.0 H.O. orange top 194cc @ 3bar with. I think they are both 19lbers.

Will this cause a lean condition?

Will the computer adjust for this?

I have the ENTIRE fuel injection system out of the '86 so if I swap ALL of it at once will the '92 computer compensate for it?

Any help would be appreciated.
Thanks
Ty

craZy400 said:

Which injectors do you have?

I think the speed density injectors are different from the mass air injectors in relation to amount of fuel.

I have NEW grey top injectors off of an '86 5.0 H.O. which are 140cc @ 3bar that I was hoping to replace my OLD '92 5.0 H.O. orange top 194cc @ 3bar with. I think they are both 19lbers.

Will this cause a lean condition?

Will the computer adjust for this?

I have the ENTIRE fuel injection system out of the '86 so if I swap ALL of it at once will the '92 computer compensate for it?

Any help would be appreciated.
Thanks
Ty

Click to expand...

The 19 lb Ford injectors are tan/orange colored.

The gray top injectors are not 19 lbs, more like 14 lbs. See http://users.erols.com/srweiss/tableifc.htm#BOSCH for more info.

The computer will not compensate for mismatched injectors, you will run lean.

Not trying to hijack this post but I have the same problem except I dont have any power going to my starter solnoid and my fuel pump wont turn either. There is a round connector on the main harness inside the car(i think 9 pin) and a 2 pin on the dash harness that goes too nothing. Is it posible I have the wrong harness also?

I'm not sure if this will help you now or not,
http://www.stangnet.com/tech/maf/massairconversion.html

_jb_ said:

I'm not sure if this will help you now or not,
http://www.stangnet.com/tech/maf/massairconversion.html

Click to expand...

It helped if my problem can't be solved ,but what could i do to make it work?

I would switch back to the stock wiring...IMO.

mustangmarks said:

It helped if my problem can't be solved ,but what could i do to make it work?

Click to expand...

Since you have a 91 harness, try this...

Fuel Pump Troubleshooting for 91-95 Mustangs

Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the ECC test connector and jump the connector in the lower RH corner to ground. See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html for a description of the test connector. If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the Schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. A tire pressure gauge can also be used if you have one - look for 37-40 PSI. Beware of fire hazard when you do this.

No fuel pressure, possible failed items in order of their probability:
A.) Tripped inertia switch – press reset button on the inertia switch. The hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter.
C.) Clogged fuel filter
D.) Failed fuel pump
E.) Blown fuse link in wiring harness.
F.) Fuel pressure regulator failed. Remove vacuum line from regulator and inspect for fuel escaping while pump is running.

The electrical circuit for the fuel pump has two paths, a control path and a power path.

The control path consists of the computer, and the fuel pump relay coil. It turns the fuel pump relay on or off under computer control. The switched power (red wire) from the ECC relay goes to the relay coil and then from the relay coil to the computer (light blue\orange wire). The computer provides the ground path to complete the circuit. This ground causes the relay coil to energize and close the contacts for the power path. Keep in mind that you can have voltage to all the right places, but the computer must provide a ground. If there is no ground, the relay will not close the power contacts.

The power path picks up from a fuse link near the starter relay. Fuse links are like fuses, except they are pieces of wire and are made right into the wiring harness. The feed wire from the fuse link (pink/black wire) goes to the fuel pump relay contacts. When the contacts close because the relay energizes, the power flows through the pink/black wire to the contacts and through the dark green\yellow wire to the inertia switch. The other side of the inertia switch with the brown\pink wire joins the pink/black wire that connects to the fuel pump. The fuel pump has a black wire that supplies the ground to complete the circuit.

Remember that the computer does not source any power to actuators, relays or injectors, but provides the ground necessary to complete the circuit. That means one side of the circuit will always be hot, and the other side will go to ground or below 1 volt as the computer switches on that circuit.

See http://www.autozone.com/images/cds/gif/large/0900823d80195960.gif for a diagram of the wiring for 90-93 cars.
See http://www.autozone.com/images/cds/gif/large/0900823d801ddb43.gif for help with wiring on 94-95 cars
And
http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for more wiring help for 94-95 cars

Now that you have the theory of how it works, it’s time to go digging.

Power circuits:
Power feed: Look for 12 volts at the pink/black wire (power source for fuel pump relay). No voltage or low voltage, bad fuse link, bad wiring, or connections. Remember that on 92 or later models the fuel pump relay is located under the Mass Air meter. Watch out for the WOT A/C control relay on these cars, as it is located in the same place and can easily be mistaken for the fuel pump relay.

Relay: Turn on the key and jumper the ECC test connector as previously described. Look for 12 volts at the dark green\yellow wire (relay controlled power for the fuel pump). No voltage there means that the relay has failed, or there is a broken wire in the relay control circuit.

Inertia switch: Check the brown/pink wire, it should have 12 volts. No 12 volts there, either the inertia switch is open or has no power to it. Check both sides of the inertia switch: there should be power on the dark green\yellow (inertia switch input) and brown/pink wire (inertia switch output). Power on the dark green\yellow wire and not on the brown/pink wire means the inertia switch is open. Press on the red plunger to reset it to the closed position. Sometimes the inertia switch will be intermittent or will not pass full power. Be sure that there is 12 volts on both sides of the switch with the pump running and that the voltage drop measured across the switch is less than .75 volts.

Control circuits:

Relay: The red wire for the fuel pump relay coil gets its power feed from the ECC relay. No 12 volts here, and the ECC relay has failed or there is bad wiring or bad connections coming from it. The ECC relay is located on top of the computer, which is under the passenger’s side kick panel. It is not easy to get to, you must have small hands or pull the passenger side dash speaker out to access it.

Relay: The light blue/orange wire provides a ground path for the relay power. With the test connector jumpered according to the previous instructions, there should be less than .75 volts. Use a test lamp with one side connected to battery power and the other side to the light blue/orange wire on the fuel pump relay. The test light should glow brightly. No glow and you have a broken wire or bad connection between the test connector and the relay. To test the wiring from the computer, remove the passenger side kick panel and disconnect the computer connector. It has a 10 MM bolt that holds it in place. Remove the test jumper from the ECC test connector. With the test lamp connected to power, jumper pin 22 to ground and the test lamp should glow. No glow and the wiring between the computer and the fuel pump relay is bad.

Computer: If you got this far and everything else checked out good, the computer is suspect .Remove the test jumper from the ECC test connector located under the hood . Remove the plastic cover over the computer wiring, but leave the computer wiring connector plugged into the computer. With the ignition switch in the run position, connect a test lamp to the battery and back probe pin 22, the light blue/orange wire with it. The lamp should glow brightly. No glow and the computer has died a sad death. If you used a voltmeter instead of a test lamp, you should see less than 1 volt.

Wow... took me almost 2 days to finally get through that

jrichker said:

Copied From bbunt302

Just for reference, here's a list of all the compatible years:

89 harness should work for 86-89 as long as you're using mass air.
90 harness will only work in a 90. (B/c of air bags and dual dash connectors)
91 through early 92 harnesses should be compatible (single dash connector, fuel pump relay under driver's seat)
Late 92 through 93 harnesses should be compatible (single dash connector, fuel pump relay under the hood)

Computers from 89-92 are all the same. Look for the A9L sticker on the back cover for a 5 speed that matches your requirements. Example: E9ZF 12A650 AA" with the A9L code.

AutoZone wiring diagrams

http://www.autozone.com/servlet/UiB..._us/0900823d/80/16/71/3c/0900823d8016713c.jsp for 79-88 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/19/59/5a/0900823d8019595a.jsp for 89-93 model cars

http://www.autozone.com/servlet/UiB..._us/0900823d/80/1d/db/3c/0900823d801ddb3c.jsp for 94-98 model cars

Click to expand...

So your saying that mustangs had the fuel pump relay under the driver seat until late 92? Cuz I have a harness out of a 91, and it has the relays under the MAF, OR could it be possible that this harness is in fact out of a later year?. If that be the case My interior harness Could just work out for me.