Hey guys,

So with the warmer weather, I've finally had a chance to drive my car spiritedly (2015 IS350). However, I noticed that under full throttle for about 5-10 seconds, I get a sulfur smell after I let off the gas. I thought maybe it was the gas (I've only put in Shell V-Power 91 in this car) so I drove the car until it had less than an eighth tank, then put in Petro Canada Ultra 94. So far, I've driven about 80 km on the new tank but I still smell a sulfur smell after hard acceleration.

I never noticed this smell last summer, so I assume it's related to something that's changed. So far my car is still 100% stock so the only culprit I can think of is gas. It is possible that I never noticed it before though because you can't smell it when the windows are closed with AC on, which is usually what I do in the summer.

Does anyone else get this smell? Do you guys think it could be the "winter blend" gas that gas stations have right now?

 

Its called your cats. You're fine. Carry on enjoying the car.

Remove them and see how much it intensifies haha

 

I know it's my cat, but I've always associated that smell with cats failing. I've never smelled it in another car that was running properly. I also haven't seen many posts about the smell on here, so I assumed that it's not a normal/widespread issue with this car.

Are you saying that it's normal for my cats to produce this smell?

 

I don't think this is normal, I live in a hot climate and I never smelled this and neither did my friends who have similar cars.

 

For computer controlled cars with a cat, a sulfer smell is an indication of a rich fuel mixture. The sensor is telling the computer that the vehicle is under a heavy load and it is dumping in extra fuel.

Have you noticed a decrease in mileage? I'd probably look into checking up on (and maybe even replacing) the O2 sensor.

 

I've only noticed a small decrease in mileage since I put my winter tires on and because it was cold until recently. How can I check the O2 sensor without replacing it and checking for a difference?

 

Go under the car and check if there is any type of plastic+ rubber + foam stuck to your exhaust or any hot surface. The only time I smelled a bad smell in one of my cars was due to plastic getting burned by the exhaust.

Additionally if you have an issue with the cats the car dash will show CEL.

 

Update: So I just went for a drive. It seems like I get them smell if I go full throttle for more than 5 seconds and then abruptly let off the gas. I suspect it's putting unburnt fuel into the exhaust at that point. I did a few pulls that were shorter and didn't let off the gas abruptly and there was no smell.

I tried to look under my car but I don't have a jack and thus couldn't see anything lol. Also after my hard driving I noticed a slight hint of gas smell from the exhaust when I parked. I think this is normal though.

 

Typically the 'rotten egg' smell is indication of a bad cat, BUT, most new cars will make the smell when their new until the cats wear in.. That isn't your case since the car has been well driven.

Your probably getting some unburnt fuel.. I'd flog your car seeing as we have the nice weather today and the for the next few and clear out any carbon or build up that has accumulated these last few months..

Unless you get a CEL I wouldn't worry about it too much.

 

https://www.clublexus.com/forums/is-...m-exhaust.html

 

The smell is new detergents gas company's uses to keep your combustion chamber clean. It's actually cleaning the engine when WOT. Smells funky but heathy for our engines, if it bothers you, use a different gas station

 

Well I've tried two different gas brands and still seem to have the same problem.

Also I've been driving it pretty hard for the past week or so and still seem to have the problem. I'm gonna call Lexus today to see if they think it's normal.

 

^ that....
Had a plastic bag wrap around the pipe on my old car. Stunk for days until most of it torched and just burnt itself off

 

Would a plastic bag smell kinda like sulfur? I tried to look under for a bag or something, but I couldn't see anything and don't have a jack right now.

 

Just an update in case someone has a similar issue in the future and finds this thread:

I ended up taking it to the dealer so I can look under it and take a tech for a test drive. On the drive, we smelled it, but it seemed to be less than before. The tech said that it smells like my exhaust components haven't fully broken in yet (seems plausible as I've only done very short infrequent pulls so far). Also when we looked under the car, the rust proof undercoating was burned away near the exhaust components, which leads us to believe that that might've contributed to the smell as well.

I feel like the smell is slowly going away, but I haven't confirmed that yet. If that's the case, then either driving hard (to brake in my components) or the change in gas helped my situation.