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Discussion Starter #1
So, once again I had this happen last night. I was getting on the expressway and was at almost WOT when it happened. A couple weeks ago when I got P2149, it just shuddered for a second or two then ran fine. Last night it ran like . Could this be a throttle position sensor issue? The reason I ask is the last 2 times I got this code and the rough running, it was at 75% throttle or more. Has anyone seen any correlation between these? I will be pulling the truck into the shop today and taking the valve cover off and checking the wiring in the gasket. Since the valve cover will be off, I figure I will also check the valves as well.

Any other advise? I really do not want to take this into the stealership or another shop and spend tons of money to diagnose the problem.

TIA
 

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Mr. Vehicle Destroyer
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Sounds like you're having an issue with #5 injector that is drawing too much power and coincidentally killing the other 2 injectors it is paired with.

The miss fire code is triggered when the ECU doesn't see the proper inductive load from any one injector firing. It could be too high or too low to trigger it. (This usually happens near WOT because that is when the highest duty cycle is commanded for the injectors) The ECM has current protection on the injector power circuits to keep from frying components internally so if one or more of the injectors is drawing too much current it will shut down the power to that "group" of injectors.

Your first course of action should be to do a resistance check at the posts on top of the injectors. If all those look similar or close to the same, then you should move onto checking your injector pass through harness where it passes through the rocker box/valve cover
 
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Discussion Starter #4
Sounds like you're having an issue with #5 injector that is drawing too much power and coincidentally killing the other 2 injectors it is paired with.

The miss fire code is triggered when the ECU doesn't see the proper inductive load from any one injector firing. It could be too high or too low to trigger it. (This usually happens near WOT because that is when the highest duty cycle is commanded for the injectors) The ECM has current protection on the injector power circuits to keep from frying components internally so if one or more of the injectors is drawing too much current it will shut down the power to that "group" of injectors.

Your first course of action should be to do a resistance check at the posts on top of the injectors. If all those look similar or close to the same, then you should move onto checking your injector pass through harness where it passes through the rocker box/valve cover
I will do that. Thanks.

My next question would be why after the truck sits overnight, does it run fine? I started it up this morning and drove to work (~15 miles on the hiway) and it ran fine.
 

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Mr. Vehicle Destroyer
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coils and injectors have time to cool off. The issue with any wound electrical coil will happen once their temperatures elevate.
 
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Mr. Vehicle Destroyer
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Yes, but you can't buy just a coil it has to be a whole injector.
 

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Discussion Starter #8
So you think #5 injector is going out? Would I be able to find that out when I check the resistance? I was wondering if it could the valve cover gasket?
 

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Mr. Vehicle Destroyer
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yes, most likely the coil is shatting the bed on #5. Your second point is why I initially said to check resistance at the studs on top of the injectors. If it is bad between the two studs then the coil is bad (you may have to measure resistance while the motor is hot). If you check the resistance at the valve cover pass through and it is bad, it could be either the gasket/harness or the injector, so if you check right at the injector you can eliminate one failure mode.
 
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Discussion Starter #10
I am going to leave the truck in the shop tonight and take the shop truck home. When I come in tomorrow, I should take the truck out and get it hot then check the resistance right? If the truck is running fine, will I still see some sort of issue with the resistance? Or is this something I would need to check while it is acting up?
 

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there is a certain threshold that it has to surpass to start misbehaving. If I'm thinking right, #5 will be different enough from the other five injectors that it'll be noticeable. There will probably be even some difference in the readings at cold too....thinking that all coil resistances should change about the same since they are all exposed to the same temperature.
 
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Discussion Starter #12
I will post up again tomorrow morning after I take some readings and see where the injectors are at.
 

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Discussion Starter #13
Left the truck outside last night. Got to the shop, started it up and it ran fine. Turned lights on inside the sjop, unlocked the overhead door and then took the truck for a little test drive. It ran just fine until I started to run it harder. It took less than 5 minutes for it to start running rough again. Got it back to the shop, took the valve cover off and checked the injectors resistance. Here is what I got:

#1 - 1 ohm
#2 - 1 ohm
#3 - 1 ohm
#4 - 1 ohm
#5 - 2.6 ohms
#6 - 1 ohm

I can see that #5 is shot. What do you think about the others?
 

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Mr. Vehicle Destroyer
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I don't know what the spec is for them, but around or slightly below 1 ohm is about what injectors seem to end up at after they get some miles. The rest should be good to go.
 
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Discussion Starter #15
I don't know what the spec is for them, but around or slightly below 1 ohm is about what injectors seem to end up at after they get some miles. The rest should be good to go.
According to the service manual the injectors should check between 0 and 1 ohm.

Now, I have been talking with a guy from Exergy Engineering. Do you know of them and do you know if they have a good product? From what I have read they do quite a bit of testing on all their injectors to make sure they are up to spec. Where else can I check to get an injector? Keep in mind funds are limited so I don't mind getting a reman if it is from a quality shop.
 

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Discussion Starter #16
Shibbyutman---can't thank you enough for all the help!!!

New injector will be ordered this afternoon and will be here by Monday evening. By this time Tuesday, the truck will be back on the road!!!!
 

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Mr. Vehicle Destroyer
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No problem guy, glad to help out somebody near by. I still get down to Toledo/Sylvania about every other week.

When you do get to installing it, make sure you get a new copper washer and make sure the old one comes out with the old injector. be sure to have a torque wrench handy to run the connector tube and injector down with.
 
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Discussion Starter #18
No problem guy, glad to help out somebody near by. I still get down to Toledo/Sylvania about every other week.

When you do get to installing it, make sure you get a new copper washer and make sure the old one comes out with the old injector. be sure to have a torque wrench handy to run the connector tube and injector down with.
Gotcha. We will have to meet up on one of your trips down!!
 

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Discussion Starter #19
Got the truck put back together yesterday and drove it home. So far I think it is good to go. I am just paranoid as hell!!!!

Many thanks go out to Shibbyutman for all his help!
 

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So my truck did this same exact thing, and threw the same codes, did replacing the injector fix your issue? Did you replace just one injector?
 
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