3406E misfire that won't go away, even after overhaul

Well see if that rocker is moving like it should be,if it is then I would follow what EverLuc said.

 

I took a video of it a little bit ago running with the different ECM, here is the link:

 

I'll pop the valve covers tomorrow, look at the cam lobes again, and dial indicator the travel. I can call Cat Tech tomorrow and get the lift specs I should see on the indicator, but does anyone know off the top of their head? As of a couple weeks ago, no visible signs of wear. The cam/rockers have to be the culprit, it's had (2) injector harnesses in the last couple years, the most recent being a month ago, the engine harness is new as of overhaul... All the postings I've read about camshaft issues involve obvious signs of wear, i.e. a rocker visibly not moving as much as the rest, signs of wear on the lobe, dropped rocker roller....etc. Mine has none of this. I can bet though that the rockers have never had new bushings, even though they don't have any flop or play that I can feel between them and the rocker shafts. I will also put in a new cam sensor and see if that does anything.

 

Where is the misfire in the video? It seems like it is on high idle.

 

Did you have any bubbles in your fuel? How did they track the problem down? Was it isolated to one cylinder or did you have a misfire that was generalized to all cylinders? Thanks for the help everyone!!

 

I don't know how my reply showed up as someone else's. I really don't... The above is me replying to Everluc..... Above is also a photo of the 4 cylinder automated test results that showed #3 as not ok...until now the automated tests didn't show much except low readings for #3. This is the first test I've done where the automated tests have actually caught it.

 

they didn't track it down to a specific cylinder like in your case, Truck309 mentioned there was a bad run of reman injectors in 2012 and we talked Finning (the Caterpillar guys up here) into replacing them after they admitted there was in fact issues with some injectors. the tech that came to our shop to replace them discovered that every injector had burn marks past the tips from blowby and inspected the seats with a borescope. all of them were badly leaking past the tips and Finning agreed to replace the head. a poster here on Truck309's thread, truckmachinist I believe it was, said from the start it was injector seats, in my case he was bang on. he had built his own tool to re-grind the seats after he found out this was an issue on other trucks with the exact symptoms my truck had.

 

Another easy thing to rule out would be hanging Jake brake. Would need shorter bolts or spacers and run with Jake housing off. Does it have 340A Jake's? Those are pretty sensitive to over adjustment and need to wait for the oil to completely purge.

 

This^^^^^^^^
A lot people when doing the overhead dont purge the oil out of Jake slave when doing the adjusters. Recommended procedure is to screw the auto lash adjuster down so there is valve spring pressure pushing on the slave to purge the oil. Then back out and make your adjustments.
Theres been many exhaust rockers broke off because of wrong lash setting.