What should I check next?

[MrShanks2U]

My truck has been making this noise for a couple months now. It sounds like popcorn popping. It's a different sound from the pinging sound that I took care of a few years ago. It's lower pitched and not as fast. My truck only does this while driving it. Revving the engine in neutral, it won't do it. And it only does it in the upper end of 2nd gear and lower end of 3rd gear. Thinking it might be the pinging thing again, I tried running 93 octane gas for a while but that did nothing. I then decided to replace the spark plugs (Autolite double plat.), wires (autolite), and ignition coil (BWD). I haven't replaced the plugs in many years, since the last time I took care of the pinging. The plugs had about 100k miles on them and the ignition coil, which has never been replaced, had 226K miles on it. After all this, the truck definitely runs better, but it still makes the noise. I haven't received any CEL codes in several years. Where should I check next? Should I bother checking the DPFE since I haven't received any EGR codes?

FWIW, I do have a slight coolant leak coming from the timing chain cover. I have to top of the overflow reservoir about once every month or two. But I don't see how this could relate since the noise is only heard when driving. But please correct me if I am missing something here.

Thanks.

 

[helpme]

What I heard...

that kind of poppin is due to a worn cam shaft.

 

[modelageek]

My truck has been making this noise for a couple months now. It sounds like popcorn popping. It's a different sound from the pinging sound that I took care of a few years ago. It's lower pitched and not as fast. My truck only does this while driving it. Revving the engine in neutral, it won't do it. And it only does it in the upper end of 2nd gear and lower end of 3rd gear. Thinking it might be the pinging thing again, I tried running 93 octane gas for a while but that did nothing. I then decided to replace the spark plugs (Autolite double plat.), wires (autolite), and ignition coil (BWD). I haven't replaced the plugs in many years, since the last time I took care of the pinging. The plugs had about 100k miles on them and the ignition coil, which has never been replaced, had 226K miles on it. After all this, the truck definitely runs better, but it still makes the noise. I haven't received any CEL codes in several years. Where should I check next? Should I bother checking the DPFE since I haven't received any EGR codes?

FWIW, I do have a slight coolant leak coming from the timing chain cover. I have to top of the overflow reservoir about once every month or two. But I don't see how this could relate since the noise is only heard when driving. But please correct me if I am missing something here.

Thanks.

that kind of poppin is due to a worn cam shaft.

if I were you I would change the cam shaft syncronizer as helpme suggested.........I think it is suggested that you change that out at 80k,,,,,even if it is not your issue it might just save your engine anyways.......when the syncro fails the engine keeps running but the oil pump stops.......it only takes a few more seconds and your engine is toast..

 

[MrShanks2U]

that kind of poppin is due to a worn cam shaft.

Ok, my question to that would be...if it was the cam, would it not make that sound through all RPMs, no matter what gear I was in?

I'm not trying to be difficult, its just when it comes to something I am unfamiliar with, I want to learn as much as possible about it.

Thanks.