I was changing glow plugs so since I was there I re-torqued injector, rocker arms and ohmed everything before putting it together. So before I started doing the GP's I checked injector ohms at the 42 pin plug as I am checking the ohms I found some were coming up 3.0 - 4.0 ohms. Then I went to check them at the VC outside plug using a repair harness since it is easier then trying hold it on the pin in the VC plug. Well they were coming up 3.0-3.7 ohms until I get to #5 it is 2.7 ohms.

Could having lower then stock spec (3.5 - 5.0) ohms be indicative that something is wrong or that something could be going on with the injector solenoid? Is 2.7 ohms something to worry about ?

 

The solenoids have a nominal resistance of 2.9 ohms, probably at 75°F. I don't think there's an actual spec, per se, for resistance measured through the wiring harness but I'd expect it to be at least 2.9 ohms. Honestly, I don't know if it's something to concerned about or not. Personally, if it wasn't setting a code, I'd be inclined not to worry about it.

 

Thanks for your input I had never heard that solenoids have a nominal resistance of 2.9 ohms. But why then would the service manual say 3.5 - 5 ohms? And with that being said how or why would I get 2.7 ohms? I have no codes and truck runs fine. I would have liked to hear that others have gotten ohms reading like me without issues down the road. I guess I'm the only one that has gotten a below spec ohm reading. Which doesn't put my mind to easy. But thanks for trying to put my mind at ease I guess it is my OCD getting the better of me.

 

I have worked with more solenoids than the average human. One of the devices I work with regularly has 580 of them, another has 414, and several others have over 300 each. In my previous career, I had 85 similar machines on my rounds - with the big boy at 896 solenoids.

Getting the lower reading on a solenoid usually takes a really good meter and a solid connection with the probes, but meters generally have a rough time being real accurate to the tenth of one ohm - unless you have an expensive Megger. As the OCD baseline member on FTE, I'd let that one go.

I do not like it when one reads over 1 ohm higher than the others (with my meter). My meter shows about 2.8 - 3.2 ohms on the solenoids, while an inexpensive meter would show 3.3 - 4.0 ohms on the same solenoids.

If you really want to see what's what, you can swap the solenoid packs and take another reading on both solenoids. Another test is to check all your solenoid pins on the 42-pin connector in reference to ground.

 

In my year long battle to get my truck to stop shaking at idle, I ohmed from the 42 pin and got readings from 3.4-9.0 across the board. I've ohmed them before with consistent readings, but this time I thought Hallelujah, I found the problem. I summoned a box with yellow tape and replaced the VC's and UVCH's. Now I read 2.5-2.6 ohms. My problem still exists, but at least you're not alone with your readings.

 

The HEUI injector does not lend itself well to a smooth idle. My experience has shown it idles great when cold, and is fickle when warm. The only single thing I've done that had a real impact on idle was the Swamps 140 IDM - and that kicked the shaky idle right in the soft parts. I wouldn't push the Swamps on stock injectors, I'm not sure there is enough return on investment. For big nozzles? Oh yeah... the benefits grow with nozzle size.

 

I don't want to hijack, so I'll start my own thread on this subject. When I installed my 200/80's they ohmed at 3.2 at the solenoid, so the lower reading at the 42 pin a year later has me perplexed. With the new VC and UVCH the engine sounds louder as if the ICP is higher but AE shows it's the same.

 

I'll have a series of questions when you start your thread.

 

Thanks guys for helping put my mind to easy. I'll sleep better now knowing this is not uncommon.
Beers for all !!
Merry Christmas
Thanks for that insight on meters. I have 2 of them nothing fancy I did have a nice Flute that a friend used and blow it up. How I don't know...plugged it into 440v who knows but it was fried. And all I get is I don't know and I'm sorry. So of the 2 meters I did use the better of the two. So after I read what you said I went back with the crappy meter and that 2.7 ohms was 3.0 ohms. Mind you I found that there was even a difference after subtracting my baseline ohm #. I now have a difference ranging from 2.7 to 4 ohms so I am within 1.3 ohms across the board. Now I have a baseline of what I have.
It means alot when someone like you who understands the OCD to tell me to let it go
Speaking of my OCD since I had the VC off I waxed them since they are in great shape for factory paint and all stickers are in good shape. Well I put a scratch, the first scratch in my Rt VC today putting it back on today. It hit the a/c drier bracket I am so Mad at myself !! Something so simple and I mess it up.

 

Waxed the VCs? I wonder how that's gunna look when the 200 degrees melts the wax.


Since apples are waxed, I am prompted to offer food for thought: I read where a member Rhino-Coated his VCs and this knocked the noise under the hood waaaay down. This makes perfect sense to me, as I know the injectors play a huge role in noise up front. Besides... this would cover that scratch.


I have been thinking about this since I first read it, and it is a mod I am seriously considering in the future.

 

I figure someone would have been like what is wrong with you...Waxing the VC. This is actually the 3rd time I have waxed them I do every time I'm down that far and have things apart. Believe it or not the wax holds up fine and holds the gloss until I take Simple Green to the engine. Like I said OCD makes me do all kinds of stupid things. Between the injectors and turbo these 7.3's are noisy but lucky for me I am hard of hearing and it doesn't bother me too bad.

But I agree anything you can do to hold down the noise levels would be helpful. So I guess using something as dense as Rhino lining would help. I myself to deal with under hood noises have been looking into a better hood liner set ups but I am still up in the air on which way to go. I also think if I keep working on putting my sound system together I can just drowned out the noise with some music. Rock & Roll

Now as long as I have you here I followed your injector re-torqueing guidelines. I started at 50in/lbs to make sure no Orings needed to be replaced then 95in/lbs still all good. Then I went to 127 in/lbs I went to 127 in/lbs because I don't trust my in/lbs torque wrench to be that accurate. The calibration sheet says 3% + or - but my goal was 130 in/lbs and the last time I did it I torqued to 120in/lbs. Well on the left side I only got about a 1/8 of turn before it clicked which seemed about right. But when I got to the right side I was about between a 1/4 to a 1/2 turn before clicking. So it made me wish I would have done another step at maybe 110 in/lbs or something. I should have gotten a good baseline on how much they loosened up in the last 15-18k.
Does this sound way off base?

 

Old post, but someone might find it useful reading through to find out that just yesterday...

I ohm'd out my injectors and the different harness sections to get 2.5 and 2.6 ohms for each injector on a cold engine, but then 2.7 - 2.8 ohms measured at various points throughout the harness all the way back to the IDM.

So... it varies. The reason I was doing all this is because I was getting codes P0273 (cylinder 5 injector circuit low), and P0603 (Internal Control Module Keep Alive Memory Error), and P1316 (IDM codes detected), on a 1 month old refurbished NAPA auto parts IDM that was causing rough idle and stalling. (1 month ago I installed all refurb'd motorcraft injectors, new glow plugs, new manifold cover 1-piece gasket sets, and so on). At the time of install, the injectors resistance was 2.9 - 3.1 ohms)

I cleared out all of the codes on the entire vehicle, twice, and then disassembled each harness and measured continuity, resistance, and verified no shorts to ground. Everything checked out normal. However, when inspecting the male / female connectors in the harness plugs, I noted minor white oxidation on some of the male connectors. So with a scalpel I gently scraped the edge of each pin, squished dielectric grease into the female ends, and reassembled everything.

All of the problems went away, and my injectors are still at 2.7'ish ohms. Did the Ford drive tests for about 35 miles and no problems.