Hey guys, I've been doing some digging on this, but I can't find anything that quite matches my issue and I've run out of reading capacity. For a long time I have been noticing extended cold cranks as compared to my dad's truck which has 50k less miles. Hasn't been much of a big deal until lately the crank has been getting longer to the point where it is noticeable and bothers me.

When the truck finally fires (10-15 seconds) it will sit and idle no problem, maybe a little rough, but that's about it. It will also run a little rough if you start driving it right away but will smooth out fairly quickly. When it first starts it is usually accompanied by a small puff of white smoke.

As a quick run down it has had the injector o-rings, glow plugs and UVCHs replaced about 36k ago. I can verify it isn't the glow plugs or the harness because it would start reliably down to -25 without being plugged in.

My thought is the injectors are just nearing the end of their useful lives (248k). Does this make sense?

Thanks,

Baatzy

 

Check the HPOP reservoir before a cold start, mines usually still 3/4 full in the morning. If its low/empty then yes your oil is draining and it takes that long for it to refill and build pressure.

I'm no expert on how/why the oil drains through the injectors but you are on the right track.

 

Couple things.....

Q:When the O-Rings were replaced, did you re-torque the injectors while warm (140*F)? Many times people can go back in and get a 1/4 to a 1/2 turn.

Injectors do get "tired". I have see them needing to be replaced because of poor maintenance at 50,000 Miles and then again not seen a "Bad" one at 500,000 miles. although we sent those out anyway - it was a refresh job and the customer wanted them done. Otherwise we would not have done it. So we can condemn them. We just need to do a little testing.

What more likely is your HPOP is tired or your injectors need some Medicine.

What is the KOEO ICPv? How fast does the ICP climb when cranking? What is the DC% during cranking? This will give you a way forward.

Another thing that will not hurt is to use Hot-Shot-Secret or Archoil 9100 with an oil/filter change. But (Archoil works best for this as it ratio to oil is very high) introduce half the product directly into the HPOP after vacuuming the reservoir and start, let it run for five minutes and repeat a few times. Put the remaining in the Crank Case.

*Putting it directly into the HPOP allows the virgin product to enter the oil rails and injectors without any contaminates so it performs its best.

 

You could still have one or two most likely bad glow plugs. Or even a bad GPR. When mine went out it would crank and crank. I heard it click and didn't even think about it. If you here it click, it's turning off to soon if cold.

 

Valid points by everyone.

Saturday was my injector re-torque day. It has been a few months since I installed them and when I did, I followed Tugly's advice and did the initial install and torqued the injectors to 120 in/lbs. and then cranked the truck w/o VC's and waited the long 20 mins for the temps to rise above 160*F. I then hit them again with the torque wrench but first I reduced the setting to 90 in/lbs. Nothing turned. I then went up to 100 in/lbs and 5 of the 8 hold down bolts turned. So, long story short, I hot torqued them to 120 in/lbs.

Fast forward to 09/12/15 and I remove the VC's and start at 70 in/lbs on the TW. Nothing turned until I got to 85 in/lbs. and every one of them had turned by 105 in/lbs.

The reason I went back under the VC's was because I was starting to experience longer crank times and an ICP that even at WOT was only making it to about 2750 with a high IPRDC. I was beginning to have a little oil consumption too.

Now she cranks right up in 48* weather and my ICP goes straight to 3000 with very little IPRDC.

So, monitor ICP and IPRDC and before you drop the money on new, remans, or rep injectors, check the torque on the hold down bolts. Spec is 120 in/lbs. I now go a little more. If you find that the existing torque is below about 75-80, spec is lower, you should replace the o-rings again. The next time I go under I will replace mine as well.

Do you have any oil consumption?

 

Jhl3, that's pretty interesting. Back in March I got together with whitebuffalo and we did some data logging. Everything looked good back then, but I guess I should do some more data logging. I have been having a little bit of oil consumption but it hasn't really changed since I bought the truck.

If I could get back to super reliable cold starts that would be awesome, because that's why I was considering new injectors. There are times where the truck lives in -45 degree weather and I need it to be able to start.

If I get a chance later this afternoon I will do some data runs, but I will have to see.


Baatzy

 

If the injectors are starting to actually go bad, ie: the poppet clearances are getting out of spec, then once it gets below 50*F or so, you will start having cold start issues. 5W40 and plugging in will negate it somewhat, but you are on borrowed time at that point.

 

If you had gotten as low as 75 in/lbs, this is what you would see and hear:

• Your idle IPR (ICPDC) will climb higher than normal. You might say "Huh, I thought that used to be lower, but it's only a couple of percent - no big deal". A couple of percent difference in IPR at idle is a very big deal - that can be 20-25% difference off the norm.
• A bizarre knock starts right about here. You'll hear it and not recognize it, but it's the injector tip starting to lift off the copper washer during the combustion cycle. It's only a little at first, but it never improves on its own - and it [i]will[/] get worse. Once the injector is loose enough, your cups are exposed to the combustion pressure and heat.

The book says replace O-rings when torque gets below 50 in/lbs. After my experience with injector noise and ICP bleed at 75 in/lbs, I say 75-80 in/lbs is the threshold for replacing O-rings.

 

I remember the noise of a loose injector, I watched plenty of videos on it when I thought I was having an injector coming loose.

Now that you Rich brings up the elevated IPR DC at idle that makes me wonder. What does a low DC at idle mean? For the last 2 years my truck has idled at about 5.5% duty cycle......

 

So here is my data run. Ambient temp was about 65, the truck was cold for this start. I started it up and drove home, doing a WOT run through a few gears.


I apologize that I don't have EOT on the graph and I also apologize for the scaling on stuff, my computer is being a pain. If I need to adjust the run or something to zoom in on data, let me know.




Ignore the huge RPM spike, computer connection issues...

 

After taking some time to look this over, this whole issue may be the result of a worn or dirty IPR. I would suggest dismantling, cleaning and re-sealing and see where that get's you for $20.

Question: When coming to a stop, or a turn where deceleration is necessary, does the RPM drop to say 500 RPM's and then return quickly to 650 RPM's. If so, seek the IRP prior to dropping cash.

 

I bet you're on to something with that IPR, it behaves exactly like you describe if I drop the engine to idle real quick. Does anyone have a link to instructions for a full tear down and cleaning of that guy? I know I've seen a thread about it before but I can't find it for the life of me...

Thanks, Baatzy

 

Almost invariably, that means bad ICP sensor (they read a fake high when they fail). That will give you anemic power... maybe even a stall at idle. Of course, that depends on the injectors you have in there.

When you play back a file, you can configure your mins/maxes to anything you want for better scaling. You can then zoom in with the magnifying glass to change the amount of time shown on the scale. You can really tighten it all up with a few clicks while loading the file for playback, and while viewing.

 

Rich, that's what I thought at first as well, however ever since I can remember, the truck has always idled at that low of DC. I have had 3 different (2 known good) sensors in the truck and they all give me the exact same readings.

I will agree my truck feels somewhat anemic, power wise, but I don't know if it really is or if that's just how it seems, seeing as I have never had another stock truck with the zf6 to compare to....

I apologize again for the scope of the graph, AE is on my school laptop and they were doing a bunch of updates through the system and my laptop was doing good to upload the picture.

Baatzy

 

Update on this. I finally got around to doing an IPR rebuild yesterday. So far it seems to have improved the situation.
I have not been able to do any data logging yet, but if I get a chance I might give it a try and post it up here. I am curious to see if my idle duty cycle has changed at all.

Thanks for the help,

Baatzy