I have had an issue with my truck (130,000 miles CA emissions) for a couple years now that is driving me and my wife nuts. The truck runs great all Summer long except when I go the mountains or when it gets cold in the winter. Was camping at the end of June at about 10,000 feet and my truck sat overnight. At about 3 in the afternoon go to start and it would not go. It was 78 degrees out! Plugged into generator for about 3 hours and got it to go. I had Rotella T6 and archoil in it. Voltage was about 12.4 to 13.

I replaced all 8 glow plugs (with motorcraft) the next week. About a month later, went camping and had the same issue (58 degrees). FYI, I had put a new air filter and fuel filter on at the beginning of June. If I plug it in for about 4 hours, it starts just fine.

I had my batteries load tested and both came back good. I have not had any codes on for glow plugs or the glow plug module (cali)--or anything else. Did injector buzz test with android app, all buzzed about the same. Did contribution test with app, only injector 8 came up with anything. When my issue happens, the starter cranks and some white smoke wafts out of the tailpipe. Once it starts, it runs like nothing ever happened. It does not lope or run rough. There is light white smoke for a few minutes but nothing heavy.

Any ideas? Injector Stiction? Glow Plug Modue Relay? PCM? Truck is stock except for edge evolution tuner that is not used for tunes, only used for gauges. Thanks in advance.

 

17 year old truck

what about poor connections on the battery cables.. at frame and starter.
or the battery cables going BAD....
start at the easy and cheap F I R S T.....

YES, battery cables DO GO BAD..... OLD days.. cables lasted 4 to 8 years.
Diesels are more sensitive to power LOSS... because of glow plugs and being a diesel engine.

 

Is the original PCM in the truck? If someone ever swapped it out, or had it re-programmed, it might be looking for a GPR instead of the module. I'd recommend picking up a cigarette lighter voltmeter (search for one on amazon, they have a lot of good options). You can use it to tell if the plugs are actually lighting or not because you will see a big voltage drop when you turn the key on. After the truck starts, they will continue to run and then shut off after a couple of minutes. The voltage will increase back up to ~13.8v when they turn off, but expect voltages in the 11's when they're on.

 

I have thought about my cables needing replaced. I tried doing an ohm test and it seemed to check out. I did cable from battery to starter and from solenoid to battery. How would I know if PCM might have been swapped at some point? Or how do I know if it might have a federal PCM?

 

What does "I tried doing an ohm test and it seemed to check out" mean? Did you do the test or not? Where did you measure from? What were the measurements?

You could disconnect one of the GPCM plugs and see if it throws any GPCM codes. If it doesn't, then you might want to delve deeper into the PCM side. If it does then you know you likely have the correct PCM. Someone posted a really good diagram of the GPCM system in this thread: https://www.ford-trucks.com/forums/1...0683-code.html

Someone in your other thread also said it sounds like it might be worn injectors, although with 130k miles that would be premature. How often do you change the oil and what brand, type and weight are used?

 

Moved to the 7.3L PSD forum.

Stewart

 

If I remember correctly, I did the ohm test from the positive post wire end down to the connection at the starter. The resistance was 0. Also did it from starter solenoid down to starter and there was no resistance. I was trying to do this with no clips on my multimeter, so it might have moved when I crawled under the truck. I disconnected both GPCM plugs and no codes were thrown. This is why I was thinking maybe a PCM issue. I tried to see if there was a barometric sensor in my truck but read it is baked into the PCM. I thought this might explain my issues at altitude on 78 degree day.

 

The ohm test I was talking about was for the glow plugs themselves. Testing the resistance of a battery cable with a voltmeter is like testing the plumbing system of your house with 1 psi of water pressure. It will tell you a little about the system, but not all you need to know.

Here's a good video on testing the plugs:
I have never needed to plug my truck in, but the coldest I've started it was only about 30 degrees.

 

Also, as I stated in my original post, I don't have any mods except for an edge evolution tuner. I used a tune once about 3 years ago for a week and my transmission went out. I now only use it as a monitor for EGT, Transmission temps, battery voltage, and boost. How much should voltage drop when waiting to start (glow plug cycling)? Mine might go from 12.8 to 12.4, but nothing huge. Is it possible the tuner fried certain components of my PCM?

 

12.8 to 12.4 is just the radio and PCM getting full power. If your voltage isn't dropping any lower, your glow plugs aren't even trying. Mine drops from 12.4 to 11.1. The plugs are a BIG current draw.

I don't know if it could have damaged your PCM or not (I doubt it) but I don't really know anything about that tuner. With a GPCM, no plugs burning, and no codes, something is fishy.

 

I have also used android apps Torque Pro and Car Gauge Pro for monitoring and checking codes. I downloaded all the ford codes. I don't remember seeing a big drop in voltage with those either. Tomorrow morning is supposed to be coolish here in Colorado, so I will see if it is any different. These apps did not find any codes. Car Gauge Pro can do a injector buzz test and cylinder contribution test. Both of those tests worked, so I assumed there was communication happening from the PCM to at least the injectors.

 

It was 80 degrees when I started my truck for the first time today. The plugs came on and stayed on for about 30 seconds after the truck started. If it's at or near operating temp they won't come on at all.

 

I'd be all over replacing the relay with a stancor. Sounds like yours is a teenager that wants to get out of bed when no work needs done.

Denny (if it's aged, it's very probable)

 

If mine had the "brown can" relay, I probably would have replaced it by now. The glow plug module on mine is around $200 bucks to replace. I hate to keep chucking parts. I figured if the module went bad I would get a code.

 

This is exactly what was going on with my truck! Plugged in for 3/4 hours it started fine. But if I didn't plug it in, it would not start...even at 50*. I replaced all my GP's and run a Stancor GPR and ran a LED to the relay so I knew it was working. Still no start...I ended up replacing all 8 injectors. It turns out 6 of the 8 were original with 350K on them. The truck will now start at -10 without being plugged in, she'll bitch but she starts.

The Archoil you're running will deal with any stiction assuming you're running it full strength. Although Stiction isn't as big a concern with the 7.3L.

I'd start with load testing individual batteries, clean all connections. You mentioned your GP and battery voltage. My voltage drops to 11+/- until the GPR shuts off, it then jumps to 14.