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No Injector Pulses


mroe66

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Bottom line on this one: No injector pulses using a Noid tester.

Background Info:

2003 Ranger 3.0, was working perfectly and my nephew who will remain anonymous for stupidity sake, went to the local mudhole and tipped his truck in a monster truck rut.

This rut was full of water and he had his passenger window open. Water/sludge flowed in up to the gear shifter. When the truck was righted mud went over to the driver side.


What I have done so far:

Cleaned the engine, replaced the plugs, pulled the intake manifold off and cleaned and reinstalled, changed out the crank position sensor.

Now the weird thing is that I can spray carb cleaner into the intake breather and the truck starts for a few seconds till it burns the carb cleaner out. But the truck will not start from the key, it will crank from the key, but won't start.

I have verified that I have good fuel pressure at the fuel rail. I put the noid kit on all of the injectors and none of them are getting a signal.

I even installed a replacement brainbox to rule that out since it sits on the passenger side firewall and had mud in that area.


I guess my bottom line is, what is needed to provide the signal to the injector?

Any help would definately be appreciated.


Mike
 


Rock Auto 5% Discount Code: 70D65189E6D8FF: January 5th, 2022

Earl43P

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I believe that spark is driven by the Crank Sensor and injector timing is controlled by the Cam Sensor, which is driven by the cam Synchro, which is in the place of where a distributor used to fit, center aft, right at the firewall, buried.

Its pinout (in 2000) is
GY/RD wire to PCM 91
DB/OG wire to PCM 85

If you leave the PCM connected and backprobe the DB/OG wire either at the PCM or CMP, you should be able to observe the pulse that occurs when cranking. Might be AC or DC millivolts so try different ranges on your meter.

You should have 12v on the GY/RD when the key is Run or cranking.

Next is to verify you have 12v at the injectors (PCM applies the ground when an injector is commanded to fire). That will be the Red wire, which also goes to the MAF (to give you another place to check for that power), again key in Run.

If you haven't already, go ahead and clean that big square connector (C124), top left rear of the engine. And clean up Ground 102 right next to the PCM.

Report back what you find / don't find.
 

mroe66

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I checked the Voltages and they are there.

My meter isn't sophisticated enough to show pulses. Working on that.

From what it looks like, the PCM is not sending the ground signal. I can put my wire probe to the ground wire for the injector and touch a frame ground and my Noid tester light works. That tells me the PCM is not sending the signal.

I went ahead and changed out the Cam Position sensor. That didn't change anything.
 

mroe66

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Finally Found it...

Ok..

I finally figured it out..

The original PCM module was bad. Even though it could communicate after I cleaned all the mud out of it.

When we swapped out the PCM I forgot the key was paired to the PCM. When I tried starting the truck, the anti theft kicked in because it didn't recognize the key.

I went back to the guy I got the PCM from and luckily he had the key for the truck. We pulled the key cylinder assembly and popped it into ours and the thing started up just fine.

We are now in the portion of reassembly, retightening things and making sure everything is hooked back up.

I appreciate all the help you have given us...

Thanks..
 


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