Is it a lean condition? That is what it means on my bike and it's time to rejet. My truck isn't doing it really badly but the fact that it happens at all bugs me. I'm not hearing it in the majority of the posted sound clips either.

The thing is though, my truck is almost all stock in the things that effect air volume throughput. Brand new Jasper engine (just turned over 1k mi) and magnaflo muffler too. Only thing that hasn't changed recently is O2 sensor, cat, and exhaust manifolds.

I'm sitting here thinking to myself: what could be causing a lean condition? clogged cats?

The reason I replaced the motor was theree cylinders fail a wet compression test and I had also determined the plenum gasket was bad for probably some time. I guess it makes sense.

Has anyone had replacing a cat fix decel popping?

 

mine does it when im slowing down and the torque converter unlocks, and the rpms jump a little. Personally I like the popping and don't think its anything to be concerned about. If anything I think you would be running at tad rich and it is "back-firing". Thats just my thought on the subject but im also really not sure at the same time. My truck popped when it was stock, and does it with the headers, highflow, and whats left of the cat back Still running strong.

 

I know on my bike, a lean condition causes it to pop on decel as there is still unburned fuel in the exhaust and it detonates in the pipes (burns incompletely in the combustion chamber due to being too lean). As far as on these trucks, I would imagine it could be caused by your upstream O2 sensor reporting that it's richer than it is, so it leans out the mix. How do your plugs look?

If your plenum was leaking for a long time it's highly possible that it killed your cat.

 

Good question. Maybe I'll go have a look.

 

Super clean. Please see pics. Sorry abou the low fi cell pone quality.

These are presumably oem heat range since they are right from the Jasper install kit, and this thing hasn't been overheating at all...pretty sure this means lean condition.

Hard to see from pics but there is very minimal dry black carbon buildup on the metal ring that surrounds the center electrode insulator. The electrodes and insulator are bone dry and look like the cleaning lady has been in there scrubbing them at night when I go to sleep they are so clean. Maybe since I only have a thousand miles on it there hasn't been time enough to get the dirty yet?

Question is why? I guess I need to do this before and after cat pressure differential test others have talked about. Probably wouldn't urt to throw a new O2 sensor at it too I suppose.

 

I think you guys are right that it is a lean condition (instead of rich like I said earlier). Mine doesn't pop when the truck is in open loop (cold) and that is when it runs rich. Still, I wouldn't worry about it too much.

 

How do you put it in open loop mode? I wanna try that.

I'm not worrying about the slight popping too much I just want the old girl running tip top.

 

While the truck is warming up, its in open loop. Ignores the sensor inputs. Once its warmed up, it goes to closed loop, where it adjusts your air/fuel mixture by using the sensors. You can't really put it into or take it out of open/closed loop operation manually, as the computer does this automatically.

 

Open loop is run when your truck is cold. When your truck warms up and the O2 sensors warm up, the computer leans out the fuel mixture. This is closed loop. You cant change it.

Damnit Jason you beat me!

 

gotcha. thanks. I guess that is why it wasn't popping when I was out there playing with it in the driveway after it's been sitting all night.