Is350 F-sport Exhaust Soft Backfire?

[dbguru]

I just recently traded in my '08 250 for a new '09 350 with F-Sport intake and exhaust. I absolutely can't believe how much more power this car has over the 250. It is a lot of fun. Anyway, when coming to a stop, I sometimes notice what sounds like a soft backfire. It is by no means a traditional backfire that would wake the neighbors, but it is loud enough for me to hear the soft pop from inside the car with the windows rolled up. It it not consistent, but usually happens when it gears down from second to first. I've never had performance exhaust before. Is an occasional soft backfire-type sound normal with peformance exhaust? I hesitate to mention this to the dealer, even though everything is under warranty (I have 2500 miles on it). I don't want them tinkering around and messing up anything if they don't need to.

[Sidney07]

Wow, first of all, congratulations! That must be quite a kick to drive your new 350!

As for your exhaust sound and your reluctance to take it in...I'd at least mention it on the phone or when you take it in for its first oil change. I know it's not uncommon for high performance cars to have a little pop as they are decelerating.

[LEXUS IS250 AWD]

Congrats dude B) i'm totally envious :) ALWAYS WANTED A 350 but with the rough winters here & my little infant couldn't risk myself behind the wheel of a RWD.

Question: Speaking to my old Toyota Mechanic, he always told me not to down shift from gear 2 to 1, hence the limiter - but the limiter is not in effect when the rpm is lower than 2.5?. Is it not a good thing to downshift to 1st gear even if the RPM is that low?

P.S. My old Celica GTS (automatic) would let me down shift from gear 2 to 1 even when the RPM was at like 4. Loved the roar

[smooth1]

I just recently traded in my '08 250 for a new '09 350 with F-Sport intake and exhaust. I absolutely can't believe how much more power this car has over the 250. It is a lot of fun. Anyway, when coming to a stop, I sometimes notice what sounds like a soft backfire. It is by no means a traditional backfire that would wake the neighbors, but it is loud enough for me to hear the soft pop from inside the car with the windows rolled up. It it not consistent, but usually happens when it gears down from second to first. I've never had performance exhaust before. Is an occasional soft backfire-type sound normal with peformance exhaust? I hesitate to mention this to the dealer, even though everything is under warranty (I have 2500 miles on it). I don't want them tinkering around and messing up anything if they don't need to.

How many miles and how long have you had it? Is this happening under normal driving or after you have been "somewhat aggressive ."

[dbguru]

I've had my IS350 for a couple of months now. I only have about 2500 miles on it. The F-Sport intake and exhaust were put on at the dealership before it left the showroom floor. We revved it up to hear the new pipes before I drove off. All of the salesmen were coming out to look at it. One guy thought I had an IS-F by the way it sounded.

I normally hear it when I am slowing down to turn in my driveway on my way home from work. That is after having it on the interstate under normal driving conditions. The transmission is in automatic mode.

[smooth1]

I've had my IS350 for a couple of months now. I only have about 2500 miles on it. The F-Sport intake and exhaust were put on at the dealership before it left the showroom floor. We revved it up to hear the new pipes before I drove off. All of the salesmen were coming out to look at it. One guy thought I had an IS-F by the way it sounded.

I normally hear it when I am slowing down to turn in my driveway on my way home from work. That is after having it on the interstate under normal driving conditions. The transmission is in automatic mode.

I'm not aware of any ignition/fuel mapping changes in the ECU by Lexus. So, it sounds to me like maybe you have 2 or 3 conditions coming together to cause that sound. One might be that the new exhaust may have a slight air leak somewhere. Probably right at the connection behind the axle. That, combined with the Vvti adjusting right at that rev point as the transmission downshifts may be the reason your getting that. Not to mention the HKS flows a bit freer. But it should sound more like a low gurgling, than a sudden soft popping sound. In any case it doesn't sound like anything to be concerned over. You might want to mention it to them the next time you go in for service and maybe they can take a closer look a the installation of the exhaust to make sure it was done right.

[bartkat]

I think most any relatively open exhaust is gonna back off some. Try winding out on the highway in second or third and listen as it coasts down.