The last few weeks I have noticed the truck running a little rough at idle.....almost to the point of a misfire but never any CEL's. I made sure there weren't any codes with my scanner and of course there weren't. I have also noticed some spark knocking in the upper rpms that didn't used to be there. I don't have my laptop here with me so I can't look at the long term fuel trims right now (I'll do that tommorow). It feels exactly like it did last year right before the #7 injector hung open on me so I figure I might have an injector sticking open a little. I can't perform the "power balance test" that you guys (mainly Quintin) have spoken about cause I don't have the equipment for that BUT I did pull the injector plug off one by one real quick to see which cylinder had the least amount of effect on the idling of the engine and it seems the front cylinder, left bank, was the culprit because it didn't make as much difference as the others. I pulled the plug out of that cylinder and it was fairly black and the electrode tip was rounded off on one side a little more than it should. I then pulled the plug from the front right cylinder and it looked like it was supposed to, nice sharp flat electrode and a tan-clean white porcelain. I swapped the injectors and then the coil pack and it seems to still be that cylinder. I believe I have a leaky, almost ready to stick open injector and I bet the left bank fuel trim is leaned out to compensate for that one cylinder and causing my spark knocking I am hearing. Tommorow when the engine cools down and I can look at the fuel trims I am going to put my spare injector in and see what that does. What do you techs think about this? Any of you seen this before? That's about the best diagnosis I can come up with as of right now, I hope it isnt something worse.......

 

Ouch! Good luck bro! I'm sure you will figure it out.

 

dam sorry to hear it bro. my truck has developed an off and on rough idle too. but i dont seem to have any trouble in a the higher rpm ranges... i am however thowing a couple CEL's... nothing serious but i want to start to get everything addressed. im waiting for my tune and then im going to start trying to diagnose the issues one at a time...

anyway, good luck getting it figured out. i hope its not another stuck injector waiting to happen, thats a scary thought...

 

Ok, so I put in a new injector in that cylinder and looked at the fuel trim and of course they are dead even on both sides...... It still is running rough, next step is to put a set of autolite HT0's in, the plugs I should have been running all along.