My 2000 7.3PSD has a "miss". It shudders at low RPM, and there is a mild loss of power. An acquaintance is a diesel mechanic, and has a 5-star diagnostic tester. He hooked my truck up to run a few tests. When he ran the buzz test, the number 7 injector buzzed, but was much quieter than the others. The results showed a P1277 - high to low side open. It also showed another code that refered to the IDM, but I cannot remember the number (13XX ?). He ran another test (I think he said it was a demand test) where the engine revved a couple of times, but it didn't throw any other codes from that one.

I replaced the IDM and main harness several months ago after the engine died and wouldn't restart. The wires running to the passenger side valve cover harness were charred (the insulation was brittle and discolored), and this must have "fried" the IDM. I have had no issues with the engine after those replacements until yesterday.

He recommends replacing the #7 injector, but I don't understand the trouble code. What does "high to low side open" mean? I'm guessing that this is an electrical issue with the injector...not mechanical. Can someone dumb it up for me?

For reference:
2000 F-250 7.3 PSD, auto trans, 198,000mi, no mods...replaced CPS, IDM, and main wire harness during previously mentioned no-fire issue.

Any other suggestions?
I have not yet looked at the under-valve cover harness, but wiggling the plugs at both valve covers does not clear up the miss.

 

I would first check all wires and plugs from IDM to the VC..if it looks good pull the VC and check wires and clips in there..some times the rockers or push rods will touch the wires making them short out..VC gaskets are re useable

 

Maybe a 1316 code? I'm with Ron on checking the UVCH wiring and connectors.

 

Plan on doing that before replacing the injector.

 

I pulled the passenger-side valve cover today to check the UVC harness. It looked good. No burned of chaffed wires.

While I was in there, I decided to clean all the connections with WD-40 and a small nylon bristle brush. I made sure that all of the connectors were firmly seated when I put it all back together.

She started up with no lugging, no miss, and no SES light. I ran it up and down the highway for about 20~30 miles, and she is purring like a kitten. I love a free fix!

Thanks for the help.

 

glad you got her fixed ..thanks for letting us know

 

No sweat. Thanks again for the advice.
I still don't know what "high to low side open" means.

Can anyone help with that? My problem seems to be fixed, so I really just want to know to satisfy my curiosity.

Does it refer to an open circuit?




Also, While I was under the hood yesterday, I noticed a sweet smell. I looked around for a coolant leak. It looks like the neck above the thermostat may be the culprit. There appears to be a leak somewhere around that. The neck is rusty at the flange, and there are coolant stains near it. Looks like I will be replacing that today. It's always something.

 

A real quick explanation is the high side distributes the energy to the injectors and usually indicates an IDM problem , and the low side controls the sequencing (firing order).

Look at the last pic in my gallery, theres the run down on it there

Austin

 

Austin,
Your image didn't post.

 

Sorry about that i forgot to convert it to jpeg.



see it full size in my gallery


Austin

 

Dan, i sent you a pm . pm me or shoor me an e-mail with your e-mail address

Austin

 

Suggest when you have the time, pull the driver's side also.. It probably just a bad as the pass. side..

 

Will do.
It looks like it will be much easier to pull the driver's side.

The passenger's side was a PITA.

 

Much easier.. A good time to do the CCV Mod..keeps the engine compartment alot cleaner..