topher350

Okay so it has been teo months since I have picked up my 2010 is350. I've put almost 3k miles (sits at 117k), changed oil, and transmission fluid. The car has the f-sport intake and exhaust as well. I've gotten used to the sound, and i've been noticing something is a little "off." Since i've had the car, i've noticed a slight pop when downshifting/deceleration. This has become more abundant with time, and seems to come from the passanger side. The car also seems to have become slightly louder under load. Lastly, the pasenger side exhaust sounds "sloppier" than the driver's side, and also has sort of lifter tick-type sound whereas the driver's does not.

I have yet to get under the car to check things out, i'm just looking for input or advice on what to look for. Thank you!

Bichon

Check the Y-pipe (ahead of the cats), especially under the heat shield, and at the heat shield attachment points. It's a very common issue, and is often accompanied by P0420 and P0430 (catalyst efficiency) DTCs that come and go due to the cats not lighting off as quickly as they should because hot exhaust gases are venting through the perforated pipe.

AyRow89

^^ What he said. I had the same issue about a month after I bought my 2008 is250 AWD. Lexus wanted $1850 for the Y-pipe and they don't make an aftermarket one for the AWD. I was not about to spend that kind of money to remain stock. For $400, I had Midas weld some replacement pipe in. They got a chunk of metal into one of my cats and now it sounds like jingle bells between 1200 and 1600 rpms -_-. You get what you pay for... If you have a RWD, tons of aftermarket options.

Zmon

iTrader: (2)

My understanding of the F-Sport exhaust is that one of the mufflers is "packed" while the other muffler is more of a straight pipe, so listening to each side should sound different. Check the areas where the mufflers mate to the rest of the axle back, could be a rusted out gasket (tell-tale signs are black soot marks under the flanges).

SlenderKen

I believe the right one is more of a straight pipe. But I agree with the others. The issue seems to be with the catalytic converters. If you're getting backfire of some sort, it's most likely due to that.