so the other day i just got my muffler welded onto my 98 ls400. I notice my motor would ping around a quarter throttle is applied rpm ranging from 1,500-2,500. full throttle is fine no problem at all. I didn't have this problem before my muffler was put on. my car has around 120,000 on the cluster. what would it might be?

 

What octane level gas are you using?
What type of muffler?

 

How do you know it is "pinging"?
It could be an exhaust leak....

 

to actually hear pinging (what some refer to, instead of the proper name, knock) on a modern day vehicle is almost impossible...

even if it was knocking, the computer knows and retards timing, assuming the electronics are working properly, prior to being able to hear it with your ears, thus you never hear it at all...

I'm with BDSL, at part throttle, the engine isn't loud enough to mask a small exhaust leak that you might not hear at full or close to full throttle or higher RPM even...

I would blame it on shoddy welding - get under the car and see if you have any black marks coming away from the welds, usually right before the muffler, though it could be anywhere from the exhaust manifolds back...

why did you get a new muffler?