I have a 91 ranger 4.0 When you try to start it, it will crank for 10 to 15 seconds and then sometimes start, other times it won't start at all. Once it starts, it runs fine.

While cranking, sometimes the Check engine light will illuminate or flash.

I checked it out and when it is acting up it has no spark or VERY VERY intermittent spark, and NO INJECTOR PULSE.

I scaned it, and it has a code 14 in historical. (PIP)

From experiance, I assumed it was a weak crank shaft postion sensor (not enough voltage at low RPMs to signal the ignition module)

So i installed a new one...........it is not any better..... I then checked out the AC voltage output of both the new and old CKP sensor........they were identicle.......near 1 v AC when cranking......with the sensor disconected.

The ford Diagnostics are terrible.......and don't seem to help....

I checked all powers and grounds.....ok

I backprobed the PIP wire at the EDIS-6 module......when it wont start, it has 0 AC volts.....I also backprobed the SAW wire at the module...again 0 v AC when it won't start.

When it does start and run...I have AC voltage on both these wires, the voltage increases as I rev the motor.

This leads me to beleive that the ignition module is at fault, as it is receiving the CKP sensor signal (ford calls it TR- and TR+ i think) but it is not outputing the PIP signal to the computer, therefor the computer has no signal to fire the injectors or to calculate a SAW signal from. (saw is an ECM modified signal to allow for the computer controled spark advance)

Normally this would be a no brainer......it needs an EDIS (ignition) module....

But what gets me, is that once it starts, it runs fine, and never hiccups

I am not exactly sure how this system operates, but once running, I can actually UNPLUG the SAW wire (via the conveinient shorting bar plug in) and the truck still runs!!! From my calculations, once the computer has syncronized the injecors and spark....the EDIS does not need a SAW signal????

Maybe with it unplugged you get no spark advance, just basic base timing??

??

But if the module doesn't output a pip when cranking sometimes, wouldn't it make sense that while running it might not output a PIP either??? then I would have drivability issues or intermittent dies.......which it doesn't


Heelp///// any one see this before.....

 

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Welcome!

I agree, either a bad EDIS module or some some sort of problem in the EDIS circuitry. Be sure to check the harness connector when you change out the module.

You are correct, the igntion system will continue to function without a SAW signal, but it will be stuck at base timing of 10* BTDC.

The EDIS ignition will not function without a valid PIP signal. However, when dealing with computer modules and circuitry, intermittent-type problems are not all that uncommon, so you can't rule out a component just because you know that it works properly some of the time.