Poping or Misfiring Under Hard Accelearation

soutthpaw · #1 Wed, April 1st, 2009, 08:13 AM

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 · #2 Wed, April 1st, 2009, 08:45 AM

Maybe a COP???

svt2205 · #3 Wed, April 1st, 2009, 08:49 PM

I hadn't answered because I wasn't sure. Unfortunately, it occurs each and every time. However, it does not do this when returned back to stock.

I wish I knew where to look but the truck is still getting me to and from work so. It's only an annoyance right now.

svt2205 · #4 Sat, April 18th, 2009, 07:00 AM

Thought I'd follow up on my last post. This problem seems to have fixed itself. I now think I filled up with a load or two of crappy gas. I do now notice some very minor pinging but I would think our local fuel suppliers are still pumping the lower BTU winter grade fuels.

Thanks for those who tried to help.

***Jackpine*** · #5 Sat, April 18th, 2009, 10:47 AM

Minor pinging shouldn't hurt, but I still don't like it. You COULD retard the spark by 0.25 degrees, which would probably get rid of it (and shouldn't cost you much in power). I wonder if you're running slightly lean? That can cause pinging too.

- Jack

***88Racing*** · #6 Mon, April 20th, 2009, 12:23 PM

I don't like that it fixed itself?
Now there is pinging?
Could have been bad gas but maybe check the fuel filter?
Could have gotten water from the station.
Try the timing as Jack posted earlier. Keep us posted.

Lars

jfuller5 · #7 Mon, April 20th, 2009, 08:55 PM

Does this happen on take off from a stop or will it do it when accelerating while already under motion? If it does it on take off what you explain sounds like the slip yoke on your driveshaft binding on the spline and then freeing up, that gives you the kick in the but that feels like something hitting the tailgate. Pull the driveshaft and feel inside the slip yoke, is it rusty? If is feels real sharp on edges of spline it may be worn and binding causing wiindup in drive line tahe it lets loose and bangs. T see if this is the issue pack the spline with a good grease and reinstall shaft in truck and try it out. If it has a 2 piece driveshaft lube both splines. Good luck JF

Desert Racer · #8 Fri, May 1st, 2009, 07:39 PM

I had a miss I guess you could say. i added +10 for WOT fuel and it has went away and my truck seems to run so much better. I do have a aftermarket intake though.