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Strange Kill test findings today.

2K views 7 replies 4 participants last post by  polonez 
#1 ·
So some of you might know, Ive been struggling with this truck on and off since I bought it. Smokes on cold start up and has a rough idle/miss until warmed up.
Contribution tests showed Cylinder 5 to be at 89% while all the others are around 100%. Ive put in a new ( good used) injectors and nothing changed. Same symptoms and same contribution results. Swapped injectors to different holes. Same thing.
I did wash the motor before before doing the injector job as there was crud everywhere so I wanted to make sure everything was clean.
After the injector swap/ Engine wash I started getting P0606 Codes :frown2:
Killtests didnt really prove anything. Today I tried doing the kill test by manually unhooking the injector wires from the injectors.
When I took the injector #5 wires off and did the contribution test there was only a slight change in the idle and contribution tests dropped to 88.
I then put it back and took the wires off #2 and the idle changed more and contribution numbers were reversed. #2 showed 88% and the rest were 102%, including #5????
The strange part of this was I was still able to do an injector kill test on the injector that had the wires disconnected. With #2 disconnected I killed every single injector in the software one by one and everyone changed the idle.. I was surely expecting the injector that had the wires disconnected to not react to the kill test software. :|
Im lost for words with this truck. Nothing makes sense with it.
I do have a compression tester coming in the mail tomorrow and that will show if I have a bad hole. But this P0606 has me worried about more $$$$$$
The code doesnt seem to show up until I touch the throttle then the check engine lights up. :frown2:
 
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#2 ·
Do a compression and leakdown test. Good tests results clears the piston/rings/headgasket and valves on all holes. Bad test results=s $$$$

If the engine is good, then send in the injectors to Exergy or jkidd, one or more is tits up.

Or, you can keep wasting time and confusing everyone including yourself, swapping injectors and harness around until you take a sledge hammer to the truck
 
#4 ·
Yes I know P0606 points to ECM failure... But I have read some articles on here, especially 4th gen where other things can trigger the P0606.....
 
#5 ·
Sounds like either the injector harness is shorted somewhere on #5, or the injector driver is shorted internal to the ECM. With the wires disconnected you should get a code for misfire on #5.

The ECU really looks to be a part of the problem, either from programming or an internal fault.
 
#6 ·
Well with a stone cold motor. I disconnected the wires on injector 5. Sure enough no smoke on cold start. It did however trip the injector #5 code on the computer. Hooked it back up... Lots of smoke.
I also fixed the cut off fan clutch wiring today and the code didnt come back.... The p0606 code didnt show up today either but I didnt run it a long time.
Tomorrow is compression testing day. I will keep you posted. If compression is good, I will chase wiring/ ecu issues. If no compression in #5 I will pull the head.
 
#7 ·
Got around to compression testing today. Well a partial. Started with the suspect hole #5. only 95psi. Went to do the rest to see if others have problems. Got done 1,2,3 and while doing #4 the cheap crappy compression tester hold down broke!!!! What a piece of crap this mighty vac hold down thing is.!! I will make my own out of steel tomorrow and finish the test. Hopefully the others continue on as good and then I will drop the the head.
What you guys think? rings broke? hole in piston? burnt valve? Bent valve? I automatically assume broken rings or hole in piston but as my old man pointed out that I have no blow by and rings or piston hole would cause blow by... He has a good point.. Hoping for a valve issue myself lol :) results so far below.
#1 550
#2 526
#3 555
#5 95 !!!!!!
 
#8 ·
finished the compression test today after building my own hold down tool out of steel.
#4 was 530
I redid #5 and got 287 this time.. pulled it apart and went again... Got the 287 again.... guess it didnt seat properly yesterday when I did it.
# 6 was also a bit low at 437.. redid it again and got same 437

Tomorrow im getting a helper and pulling the head off off to take a look.
 
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