Ford EEC-IV computer on bank-fired EFI trucks

I spent 3 + hours trying to get my truck to run a cylinder balance test…I finally decided that it just wasn’t going to do it, and on further research I discovered the cylinder balance test is only available for Sequentially Fuel Injected (SEFI) engines. The older Ford trucks are all bank-fired. Bank-fired means the injectors fire in sets of four (on the V8) instead of each cylinders injector firing at the appropriate time.

Also, the order of operations for reading codes on my truck seems to be a little different than most of the tutorials I found. I have a 1987 F-150 (302/5.0L), and this is the order of operations for the Key On Engine Running (KOER) test:

1. Set up the voltmeter (analog works best–I wasn’t getting good reads with my digital voltmeter). there are lots of other sites that tell you exactly which pins to short and connect to for the test.

2. Start the engine. After a few seconds you’ll get the engine ID pulse–it should be the number of cylinders divided by two (e.g. four pulses for a V8)

3. After the engine ID pulse you have ten seconds (or so a lot of sites say….I did these things in about five seconds) to do the following:

-Depress the brake pedal
-turn the steering wheel 1/4 turn left and right (some sites say 1/2 turn one direction….I’m not sure it matters as long as you turn it enough to give the sensor a pressure reading)
-press and release the overdrive switch if you have one (I don’t)
-A lot of sites say to do the dynamic response test (briefly press the throttle to WOT) here. I didn’t find to be the case. My ECU asks for it later.

4. About 70 seconds after you start the engine, you’ll see a single pulse. This is the ECU asking for you to briefly go WOT for the dynamic response test (just push the pedal all the way down and let go).

5. Shortly after this (within 10 seconds) you should start getting codes in the usual fashion. You’ll see a code 77 if you didn’t do the dynamic response throttle press when it was requested.

6. On bank-fired EFI trucks, no amount of fooling around at this point will get you a cylinder balance test. It’s just not available on this system. I think this is because the test works by shutting off fuel to a specific cylinder, and that’s not possible on a bank-fired system.

Hope this helps someone….