I drove to Sacramento over Donner Summit on Sunday, spent a couple hours there and started heading home. The truck was running fine with no issues coming home. At the top of the summit backed off the throttle and let her roll to the bottom as I have done over a hundred times. Went to accelerate and there was nothing there. Truck felt like it had no power. I was able to get a little out of it but it was running rough and I could feel it missing. I only live about four miles from the bottom and I had no CEL and the gauges looked good so I kept nursing it towards home. She was smoking out the pipe with no additional noises and no real power but I made it home. It took two runs at the small hill into my neighborhood.

So I break out the AE and do a scan (still no CEL) and get a P1316 code, IDM code. Do a buzz test and get P1274, #4 Hi to low open. #4 sounds real faint and weak compared to all the other injectors. Do a ohm test at the 42 pin connector and all injectors are within specs. Put it back together and fire it off, makes a little noise but smooths out and sounds good. Do a KOER test that shows "successful". Contribution test shows a P0272, #4 contribution/balance fault. A KOEO gave the same P1274. The above tests were done twice over two days with the same results.

Truck sounds good but not great. No smoke like when it was coming home. At least it will drive at this point. I did not pull the VC yet as it ohm'ed ok. No burnt connectors, no chaffed wires. Looked for (not real hard) the IDM and did not see it so it could be a wire issue from the IDM to the 42 pin connector.

Looking for any insight to fix this issue. I am having a hard time with it ohming out ok but showing an open circuit code.

Truck has about 190,000, a tuner, gauges, .50$ mod, newer Motorcraft glowplugs, glow plug controller and several other minor things done to it. It lives at 6000' and has never left me stranded. Injectors are $1000 plus so I don't want to go there unless I have to.

Any ideas?

Thanks in advance.

 

You've done your homework, Dave. The injectors measured about 3 ohms each? Usually a whole bank goes out on an IDM, not one output. I'm not a fan of the 50-cent mod, I've had it fail on me. A new UVCH has such a better connection, I don't worry about vibration or oil intrusion.

You have to pull the driver-side wheel well cover to get at the IDM - you might pull it and clean the connections to the IDM (including the ground), being sure to freshen up the dielectric grease. There was a recent thread on dielectric grease, posted by your neighbor (Tim Hodgson). It's worth a quick search.

 

Anybody have any ideas before I start tearing into it deeper?

 

Thanks Rich, I was hoping I would get your help. I am still learning about using the AE and I want to try doing a perdel reading but have not figured it out yet. I will pull the inner fender and do as you suggested. I do have dielectric grease and planned on doing that if I could find the IDM. So now it will get done.

The injectors averaged just about 3 - 3.5 ohms each. But #4 sounds real weak (on the buzz test)compared to the rest but ohm'ed at 3 ohms. I figured the UVCH would be good since all injectors tested ok.

Any ideas on the codes? Any other suggestions on what to test next? I know you have and wore out all the T shirts.

Thanks

P.S. I my wife's aunt and uncle are here right now from Spokane for my youngest daughter's graduation tomorrow.

 

Your codes and AE tests are saying specifically that all is not right with the electrical signal to #4. It could be happening when there is vibration... but behaves better while at rest. It could be a loose connection on the IDM side or a bad IDM. Click the UVCH link in my signature and you will see the whole thing all laid out.

 

Thanks, that is on the agenda for Sunday as today is my youngest daughters graduation.

 

Good luck and let us know what you find. Check the wiring really close for rubs and all.

 

Ohm it out from the IDM connector (with the 42 pin connector connected) to rule out an open circuit between there and the 42 pin connector. I posted a pinout of it here:

https://www.ford-trucks.com/forums/1...2#post14172980

If that doesn't reveal anything, you might try swapping the solenoid with #2 injector to see if the problem follows the solenoid.

 

Thanks P, That is what I have planned for Sunday prior to going to work. My question is why would I have to have the 42 pin connected if I am trying to determine an issue between the IDM and 42 pin? Why can't I disconnect the 42 and then check that portion of harness between the the 42 pin and the IDM? It makes sense to me to isolate the circuits as I test back towards the IDM, is that wrong?

I like the solenoid swap idea. To confirm, as I have not had one of these injectors out before, I can remove the solenoid screws and swap the solenoids without worrying about any issues? I did not not know if there where mating or clearance issues on an assembled injector. It sounds like there is not, correct?

Thanks

 

If you leave the 42 pin connected, you won't have to pretend to be a contortionist with the meter probes . . . You can just check between the common for each bank to each injector on that bank from the connector. You can swap solenoids around without doing anything special; they're all basically the same.

 

So if I understand you right leave the 42 pin connected just to make it easier and test at the upper valve cover connector.

And good to know on the injectors, I was contemplating swapping two around but did not really want to do that. As the issue sounds electrical it makes perfect sense to swap solenoids.

Thanks

 

Leave the 42 pin connected and test from the IDM connector. There's a common for each bank and a pin for each injector on that connector. It's basically the same as testing from the 42 pin connector, except that you'll be testing the entire path from the IDM to the injector and back.

 

Ok, got ya. Thanks for the info.

 

The pin-outs for the 42-pin, the head gasket, and the IDM are in that UVCH link in my signature.

 

Well I pulled the inner fender and pulled out the IDM. All plugs and connectors looked good. Ohm'ed all the circuits and all checked within specs. Pulled the valve cover and all looked good under the valve cover, all connections were solid. So I went to swap the solenoids as suggested by P. While I have the solenoids off I notice the armature on #4 seems loose. I read somewhere that the clearance should be less than .015". Just for giggles I spin it clockwise and it tightens up like #2. So I pull it all the way off and find a socket that is close enough to work, clean it all up and screw it back together. Nice and tight. Put it all back together, do a buzz taste, #4 sounds great (like the rest); do a KOEO, successful; do a KOER, successful; no codes and sounds great. Take a test drive and ran like it should. I need to find and buy the proper socket so I can check them all. I have no idea why that would have worked loose, especially when it did but it is fixed for now.

Thanks for all the advice and help.

If somebody knows the proper torque on the injector screws and where to find that special socket I would appreciate the info.

Thanks again.