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Idle variation, unknown cause

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Old Sep 26, 2016 | 12:13 AM
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Idle variation, unknown cause

Alright, this is long but I am trying to give all the details, not sure if some of these things relate. But I will say all of it and we can go from there.


Had a Outlet fitting on the HPOP leaking. The night I found the leak I was trying to see if the cut out between the two fittings was actually a hole that had gotten punched in the pump. So I grab a long screwdriver to probe(no jokes here ) the spot to see how deep it is. While I was doing this I accidently rubbed the screwdriver on the cable going to the alternator. As I am sure you already guessed it a large amount of sparks insude. Enough that it caught me off guard. I dropped the screwdriver which wedged itself in place and starts to glow cherry red. I tried to get it out but no luck. Next thing I know if there are flames from under the hood. I grab the fire extinguisher I keep under my seat and get the fire knocked out quickly. Thankfully the screwdriver actually melted in half and fell away from the cable. So after blowing 2 pounds worth of dry powder off the engine I survey the damage. I think I got really lucky and only saw a small section of wire loom burnt. I inspected the wires and didn't see any damage. So I replaced the loom. The next day I go to the dealership and get the parts needed for the HPOP fitting leak. The fix goes well and am back together in just a couple hours. Drive the truck to work and it seems fine. I drive it today and have noticed that it seems to be struggling a lot at first to turn over. Like weak battery's or something. But it always starts. Also when I stopped at a stop light I have an idle variation. It is going up and down around 75-100 rpms. I have looked under the hook for any loose wires. I am at a loss.

What is causing the rpm to go up and down?

Why does it seem like the truck is hard to start all the sudden? (Temps have been in the 50's at night)

Batteries are two year old INTERSTATES, glowplugs and injector o rings next week.

Any ideas?
 
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Old Sep 26, 2016 | 07:08 AM
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Well... what's your battery voltage when idling after the glow plugs have cycled off?
 
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Old Sep 26, 2016 | 10:33 AM
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I didn't see this until now. Are you asking after the night/first start up? Or anytime. After driving the truck for about 30 min this morning it was reading 14.6 at idle. Off batteries were sitting at 12.6. I did test the glowplug relay the other day. I replaced it with the larger one a lot of guys do. Going into the glow plug relay was 12.6. Coming out was 10.5.
 
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Old Sep 26, 2016 | 12:29 PM
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Wow. Sounds like a close call! Good thing you had a "fireman" nearby

I only have a few wrenches with weld marks on them from slipping on battery terminals, LOL.

So you shorted against a battery cable or terminal, or an alternator line? Got a pic?
 
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Old Sep 26, 2016 | 03:48 PM
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Altenator line to the HPOP. I have a pic of the melted screwdriver . There is just an ark mark on the back of the alternator. That's it.
 
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Old Sep 26, 2016 | 05:31 PM
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Originally Posted by Firefighter 1406
Altenator line to the HPOP. I have a pic of the melted screwdriver . There is just an ark mark on the back of the alternator. That's it.
Somebody help me with this one. There aren't any alternator lines to the HPOP that I know of

There is EOT sensor, IPR, and EBP around the front. Show us the screwdriver pic. Unless it is really tiny, I don't know that any of these have enough amps (fused) to melt it.

Gotta be sure what wire we're talking about
 
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Old Sep 26, 2016 | 05:35 PM
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He's talking about the GPR I believe?
 
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Old Sep 27, 2016 | 08:13 AM
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I am talking big cable that comes off the back of the alternator goes on the engine harness and goes over to the passenger side of the truck.

Also the idle variation only happens when it's all warmed up. When cold it doesn't do it.
 
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Old Sep 27, 2016 | 12:26 PM
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The only thing I can think that I did different was take out the check valves on the HPOP? But everybody was saying that they didn't do anything anyways. I am totally at a loss.
 
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Old Sep 27, 2016 | 12:52 PM
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wonder if IPR got damaged or something else with the heat of the screwdriver
 
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Old Sep 27, 2016 | 02:27 PM
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This is what it is doing.

324E7470-276B-4EBD-B4CA-07AE119CC27C.mp4 Video by firefighter1406 | Photobucket

Sorry, you can't hear much over the turn signal. When it goes up in rpm it runs rougher, when it is down it runs smoother. I know this all sounds crazy to me too.
 
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Old Sep 27, 2016 | 02:43 PM
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got a pic of the burned area?
 
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Old Sep 27, 2016 | 04:23 PM
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This is all I could find for burn marks. Have a couple spots on the alternator. Then the small piece of loom I replaced. And the hole between the HPOP fittings is where the screwdriver was.










 
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Old Sep 27, 2016 | 04:38 PM
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Here's what's left of the screwdriver. Half of me wants to see if Craftman would exchange it

 
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Old Sep 27, 2016 | 09:05 PM
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If the alternator had a direct short to ground with that many amps...I'm wondering if it is messed up and causing your problems?

Wow, you were lucky.

"see if Craftsman would exchange it"

Great pics
 
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