Poping or Misfiring Under Hard Accelearation

[Power Hungry]

Henry,

What level did this happen in? Also, did it only happen one time? If more than once, is it easily repeatable? Does it occur during a shift, or just during acceleration?

Let me know.

[svt2205]

Thanks for taking a look.

Jack, I'm familiar with pinging, I had 2 4.6 modulars that were heavy pingers. That said, it could still be something like that, but it sounds different. I stand with my it sounds like something that's shifted in the bed and bumps into the tailgate, a sort of pop or light thud. Best I can offer for description.

Bill, it happened any time I stepped down hard on Friday afternoon and again Saturday morning. I had originally thought it might be due to the nice warm air we had (50's) but it was only 37 the following morning and it still did it.

I was running the canned level 2. It occured while accelerating, in gear. I did not notice anything during a shift. This only occured while under hard acceleration, say more then 50% pedal. I had been running on Level 2, since 3/15 and put over 1000 miles on without a hitch.

Returning to the stock tune seems to have things back to normal.

FWIW, I have AutoTap software. You know the package that allows you to read/clear codes and monitor, on a laptop, all sorts of different sensor output. If I knew what sensors to look at, I could set things up (probably not until next weekend) and see if I can see anything.

Thanks guys for taking the time to look into this. You're time/help is appreciated!!
Henry

[Jackpine]

Henry, I'm sorry if what I said sounded like the "idiot treatment". It was just that I was not sure if you were getting repeated "thumps" (like: thump, thump, thump, ...) or only one.

In your last post, what you described really DOES sound just like what I've experienced now and then. I felt it maybe twice on our recent trip to and from California, in moderate traffic, when I would accelerate to move quickly into a passing lane. I can hear it and I can feel it, and it sounds like it's something going on behind me.

I wonder if there's any way it could be coming from the differential? (I assume you have traction lock, like I do)?

- Jack

[svt2205]

No worries Jack, I know you're trying to help. Sometimes it's hard enought to describe things when you're talking directly to someone. It's even worse when we communicate via email or posting on sites. I always try to take it all in stride, knowing that most folks are only trying to be helpful.

I'm still thinking it's engine related, as the noise has gone away, since returning to stock. Then again, it's also only in the 30's again, so we'll see when/if it ever warms up again.

Thanks again for your thoughts and help. It's greatly appreciated
Henry

[svt2205]

FWIW, I wemt from stock back to Level 2. Whatever this is, is still there. I'm going to see if I can narrow down exactly what the heck my truck is doing.

[soutthpaw]

I see Bill asked this but don't see an answer. Can you easily repeat the occurance. For example every time you give it more than 50% throttle from a stop you get the thumping??? if so what are the exact conditions that it occurs at. This is very useful info in diagnosing the problem...

[jimmyv13]

Maybe a COP???