7707

I've posted a couple times on trying to diagnose a slight miss/shudder at idle.

Had the truck looked at (sort of) today and the #1 cylinder was registering about 35-40* cooler than the other 5. 2-6 read around 218* using a temp gun and #1 was only at 180ish.

I went ahead and ordered a single injector hoping that's the issue BUT if it's not...what else could it be other than bad rings/piston etc on #1? I adjusted the valves a few months ago and nothing on #1 made me worried.

Truck's been doing this since I bought it a year ago. never gotten worse...nothing makes it better. Under throttle, towing a load, running down the road at nearly any speed it doesn't act up at all.

I already pulled out #1 injector as my new one is supposed to be in tomorrow morning...I'm just trying not to be too hopeful in that this will fix it?

If it's not the injector...how long should I drive on it as is? Truck runs well...gets decent mileage and has the power I would expect a 160HP engine to have in stock form. Hell we drove it to St Louis right before Christmas with no issue (other than front brake pads).

patdaly

I wouldn't get too excited just yet.

Any pump work that you know of been done?

chariotdriver

Why not just swap the injector with one of the hotter ones? Do a compression check for starters then pull an oil sample. Does it have much blow-by? Fuel in the oil? Doubt it's anything serious if the mileage/power hasn't dropped or isn't approximately where it should be.

7707

It appears the pump was replaced at some point not too long ago. But nothing else to my knowledge was done. I know it does not have GSK other than stock and I I doubt seriously the plate/starwheel/afc was messed with. It doesn't act like those were tweaked at all.

No fuel in the oil that I can tell.

It does have blow by but our trip to St Louis was 2500 miles round trip and it used (or leaked some from the valve cover gaskets) less than 2 quarts in the whole trip. (I have new gaskets sitting in the engine bay right now)

I was thinking about swapping out the #1 and #2 sticks but without taking it back somewhere again I have no way to tell if that really changed anything. I also don't have the tools to do a compression test myself. So if by putting in a new injector on #1 changes nothing...I know something else is wrong. At that point it may just continue as is and be a 5.5 cylinder cummins turbo diesel.

patdaly

K, I would probably check my compression next, and if it is in spec, I hate to say it, I would take it to a good pump shop and have them check the calibration of the barrels. It only takes 1 guy who doesn't know to loosen those 2 bolts and turn the barrel to screw you up. Lots of people don't have a clue what those are even for.

7707

The new injector didn't fix it...no biggie at least I narrowed it down a little bit.

I hope to get the compression checked within the next couple weeks and go from there.

texasprd

Another possibility is a worn cam lobe. You might be able to visually detect this by comparing rocker-arm movement to other cylinders, but the best way to check it that I know is with a dial-indicator. If you're talking to shops about the compression test, ask them if they have a dial indicator and if they can check cam/valve lift.