Here's the back story. We went to Indiana on a hunting trip, while there I parked the truck at the boat ramp. I didn't realize that the vegi pump was on with the diesel pump. Not that huge of a deal because the diesel will run at 60 PSI and vegi runs at 80 PSI. We left the ramp and was heading back to the hotel and the vegi tank ran dry and I guess it was throwing some air into the system. The truck started to have a miss like it was running out of fuel and I got it off the road before it stalled. I looked at the gauges and switches and that's when I realized the vegi pump was on. I turned it off and purged the system with diesel few times to get the air out.

The truck started just fine and ran fine from there. We left to come home the next day and about two hours into the trip the CEL came on. I noticed that it would come on under acceleration and off when I let off the pedal. It did this for rest of the trip home. I ran my Aeroforce gauge and came up with P1316 which I know is an IDM code.

When I got home I ran AE and ran every test I could with it. I came up with P1274 Cylinder #4 High to Low Side Open.

Now the truck has what seems like a miss and the CEL is on all the time now.

No new codes just the P1316, P1274 and two others but they are from my missing wastegate and missing AIH.

I have a few ideas but I would like some ideas or suggestions on where to look, obviously at #4, but other things. Secondly What does "Cylinder #4 High to Low Side Open" mean anyway?

 

I had that with bad remans.....Replaced with new injectors and it went away.

 

Did you do a KOEO (Key On Engine Off) test with auto enginuity?

How did #4 sound during the injector buzz test?

 

Didn't sound like the rest. Not sure if its an injector or a UVCH?

 

Here's something that Rich & Pete put together to troubleshoot the IDM codes. Basically you need to:

Clear out the trouble codes
Run a KOEO test and recheck for the 1274 & 1316 codes
Injector buzz test (firing order 1-2-7-3-4-5-6-8) see if #4 sounds different
Ohm out #4 injector at the 42 pin connector

 

In addition,

When you pull the 42 pin connector out, check the underside of the wire harness where it lays on the valve cover. Over time & miles the insulation can rub off exposing the wires.

 

Well, you're going in anyway. #4 is about as easy as it gets. I would change #2 & #4 and see if the issue moves with it. Although, you want to run the test prior to switching them to see if the UVCH or #42 Pin Harness is the culprit once everything is ready for the switch.

Costs nothing to see if that's it. And, you will have eliminated the electrical portion while doing so along with the injector. If you choose, can always button it back up in an hour and drive it until the injector or UVCH comes in.

 

Rich have a question, I thought when doing the buzz test they fired 1 threw 8 in order not the firing order, am I wrong? I believe I read that on here some time back. Haven't done mine in a while but always thought that was the way it was. Nice to see you on here Mike its been a while, sorry about your problems.

 

I'm wondering how fuel type or running out of fuel causes an electrical malfunction.......

 

Good catch Chet I believe you are correct! Sorry for the mistake, I'm a bit loopy on some meds after a herniated disk. I gotta be more careful.

Cleatus, you think there's a connection or just a coincidence? I guess we'll find out if it's a wiring or injector fault.

Edit; duh.....I see what your getting at.....injector......

I should stay clear from posting for a while.......

 

Always a man of few words.....


By all means, wring the wiring out by far the cheaper and easier option. just sounds like an injector to me.

 

So is it possible that this is just a solenoid gone bad or the whole injector? I'm going to look at all the wiring Saturday. But when the engine came out two years ago the entire harness was re-loomed and taped. I'm leaning toward the UVHC because of a broken clip when I had the injectors out last year but think I would have more problems than one injector...

 

Hey guys, sorry I'm late to the party. While the Vegi fuel pump issue is a good detail to put in there because you never know which detail provides a clue - this part is irrelevant to an IDM code, as Cody said.

Your P1274 is a colossally classic code for a UVCH, but you can't rule out the solenoid pack on #4 or a bad connection elsewhere. Whatever it is, it will not create the need to pull an injector, the head, or the motor. VCs are as deep as you're gunna go.


The buzz test is in numerical order. If you have stereo speakers, you can hear it here:

 

I would check it from the 42 pin connector first. If you had damage to the UVCH I'd look at that next. I guess you could just change out the solenoid, I've never done it. I had the same problem twice with remans, I wont go down that route again.

 

My point being that the "buzz test" and any associated codes from the IDM have absolutely ZERO to do with any mechanical issue that would have or could have been created by running out of fuel or by running anything other than #2. The fact that the OP runs an alternative fuels in his pickup will in no way cause an electrical malfunction.

To put it into "few words":

The IDM has no way in hell of knowing what the mechanical parts of the injector are doing (no system on the 7.3L does) so ANY IDM or injector circuit fault codes HAVE to be electrical problems.