gas smell when driving hard/takes long to start

[SkylineAurion]

Hey guys, first time poster here and proud owner of a xv40 2008 aurion at-x

I bought the car about a year and a half ago and this issue has always persisted. Pretty much >80% of the time I start the car, especially from cold start, it would take 4-5-6 seconds to start the car when turning the key. When it starts, the car seems like it’s choking but a second later goes back to normal. On the off chance, the car will turn off while choking and one crank will start it up back again. I changed the battery cause it was weak anyway and that didn’t solve the issue. I also wait maybe 5-10 seconds with the key in ON position before starting the car and this sometimes helps start it faster.

The other issue I have is when I drive the car hard, as in I’m accelerating hard or very hard and revving it up as much as I can in automatic, the smell of gas or LPG overcomes the cabin and the boot space, it has that distinctive fart smell to it, and the smell is very strong that I have to drive with all the windows down for a few minutes to get rid of the smell. The car still drives fine and no performance loss whatsoever. The car is actually impressively fast.

Other than that, the car is perfect.

Can anyone help me resolve these two issues I’m having? Much appreciated cheers

 

[Noodle Boy]

Hi mate and welcome to the forum.

You mentioned LPG, therefore if the car is cranked over using LPG rather than petrol, depending on the whole LPG system you can expect a few seconds at least for the fuel system to prime and the engine to start. I remember the late model Falcons running on factory liquid LPG systems to require a few seconds for the fuel system to prime after the key is turned. It may very well be normal for the system installed in your car. On another note, how does the engine operate when warmed up? Does it hesitate at all? Try starting on petrol a few times and see if the issue persists.

As for the fumes being smelt within the cabin, I suspect the opening/ flaps on either side of the rear bumper which helps reduce the air pressure between the bumper bar and the carpet trim to have failed over time. The flaps are probably opening too much these days, allow more fumes than normally tolerated to enter the cabin. I would look into that before investigating other possible leakage points. One other thing I can think of is potentially the engine is running too rich on LPG, causing those fumes to be excessively created. Maybe a major service and tune up is required. 

All the best.

[SkylineAurion]

1 hour ago, Noodle Boy said:

Hi mate and welcome to the forum.

You mentioned LPG, therefore if the car is cranked over using LPG rather than petrol, depending on the whole LPG system you can expect a few seconds at least for the fuel system to prime and the engine to start. I remember the late model Falcons running on factory liquid LPG systems to require a few seconds for the fuel system to prime after the key is turned. It may very well be normal for the system installed in your car. On another note, how does the engine operate when warmed up? Does it hesitate at all? Try starting on petrol a few times and see if the issue persists.

As for the fumes being smelt within the cabin, I suspect the opening/ flaps on either side of the rear bumper which helps reduce the air pressure between the bumper bar and the carpet trim to have failed over time. The flaps are probably opening too much these days, allow more fumes than normally tolerated to enter the cabin. I would look into that before investigating other possible leakage points. One other thing I can think of is potentially the engine is running too rich on LPG, causing those fumes to be excessively created. Maybe a major service and tune up is required. 

All the best.

No no. I don’t have a LPG system in my car. It just takes straight petrol.

[Tony Prodigy]

4 hours ago, SkylineAurion said:

Hey guys, first time poster here and proud owner of a xv40 2008 aurion at-x

I bought the car about a year and a half ago and this issue has always persisted. Pretty much >80% of the time I start the car, especially from cold start, it would take 4-5-6 seconds to start the car when turning the key. When it starts, the car seems like it’s choking but a second later goes back to normal. On the off chance, the car will turn off while choking and one crank will start it up back again. I changed the battery cause it was weak anyway and that didn’t solve the issue. I also wait maybe 5-10 seconds with the key in ON position before starting the car and this sometimes helps start it faster.

The other issue I have is when I drive the car hard, as in I’m accelerating hard or very hard and revving it up as much as I can in automatic, the smell of gas or LPG overcomes the cabin and the boot space, it has that distinctive fart smell to it, and the smell is very strong that I have to drive with all the windows down for a few minutes to get rid of the smell. The car still drives fine and no performance loss whatsoever. The car is actually impressively fast.

Other than that, the car is perfect.

Can anyone help me resolve these two issues I’m having? Much appreciated cheers

 

Hi there M. welcome to the forum. Does your car have a documented service history ? How many kays are on it ? The hard start could be fuel system related and by not knowing the answer to any of the questions I've posed, it could possibly be the first place I'd look. Your fuel filter, which is in the tank, could be overdue for replacement and the fuel pick up sock could also be choked up with crud. I'd start there before going any further. It is also possible one or several fuel injectors could also have some minute blockages too. Modern engines rely heavily on the correct fuel delivery pressure and if the system isn't maintained well enough then you can have symptoms you described.

The fumes could be entering from the boot. Check the rear section of the exhaust as I am pretty confident all the frontal firewall grommets are solid. I feel it's coming from the back, being a low pressure area of the vehicle, you can have eddy currents that tend to hang around and if there is some kind of opening back there, It is possible the fumes could enter, fill the boot and then leak through the back seat.

Also, when was the last time the cabin filter was checked too ?

[SkylineAurion]

1 hour ago, Tony Prodigy said:

Hi there M. welcome to the forum. Does your car have a documented service history ? How many kays are on it ? The hard start could be fuel system related and by not knowing the answer to any of the questions I've posed, it could possibly be the first place I'd look. Your fuel filter, which is in the tank, could be overdue for replacement and the fuel pick up sock could also be choked up with crud. I'd start there before going any further. It is also possible one or several fuel injectors could also have some minute blockages too. Modern engines rely heavily on the correct fuel delivery pressure and if the system isn't maintained well enough then you can have symptoms you described.

The fumes could be entering from the boot. Check the rear section of the exhaust as I am pretty confident all the frontal firewall grommets are solid. I feel it's coming from the back, being a low pressure area of the vehicle, you can have eddy currents that tend to hang around and if there is some kind of opening back there, It is possible the fumes could enter, fill the boot and then leak through the back seat.

Also, when was the last time the cabin filter was checked too ?

Yes the car has document service history. Previous owner was first owner and she would take it to Toyota to get it serviced regularly. It’s got 173000km. And yes, that was what I was thinking. It being the fuel filter. I’ll also put petrol injector cleaner in there to see if that sorts it out. The guy at the local auto store told me that there are two different variations of the fuel filter, one being cheap and the other being like $140. Is that true?

also about the fumes, why does it smell like lpg or natural gas, you know that smell when gas is leaking? Shouldn’t it smell like exhaust fumes/carbon monoxide? The only place in the car where gas is stored would be the air con system, wouldn’t it?

so which parts of the boot should I look at? The only place that comes to mind is the drainage holes on the floor of the boot and the little vents on the rear bumper reo area.

cheers

Edited June 18, 2021 by SkylineAurion

[Tony Prodigy]

12 hours ago, SkylineAurion said:

The guy at the local auto store told me that there are two different variations of the fuel filter, one being cheap and the other being like $140. Is that true?

There are a few brands to choose from for the 40 series, which makes you lucky because you have more freedom of choice than 50 series owners. We only have two. Genuine Toyota or Wesfil/coopers. It is believed that Wesfil has the sole manufacturing rights for the 50 series fuel filter. Nobody else makes it besides them so it's either this for around $100 or $400 from Toyota. I was lucky to have purchased a few of the Coopers when they were selling cheaply before the CCP virus screwed the economy up, so i'm well stocked for the next 20 years  

The brands for the 40 range from Ryco, AC Delco, Coopers/Wesfil, Fuel Miser, and of course Genuine Toyota. All excellent brands. I don't know of any so called "cheap" filter but typically the Ryco is the more expensive of the aftermarket options. Just check online and you'll see the prices for yourself.

 

Edited June 18, 2021 by Tony Prodigy

[Tony Prodigy]

13 hours ago, SkylineAurion said:

also about the fumes, why does it smell like lpg or natural gas, you know that smell when gas is leaking? Shouldn’t it smell like exhaust fumes/carbon monoxide?

13 hours ago, SkylineAurion said:

The only place in the car where gas is stored would be the air con system, wouldn’t it?

 

Forgot to address this in my previous post. If you suspect the smell is coming from the A/C, then it's probably that. When you start to smell, I'd pull over and put your nose to the vent while it's blowing to see if it is. It's possible you cabin filter could be contaminated and the smell is coming from this. I upgraded my cabin filter to the charcoal activated type to help filter out engine fumes, smoke etc.

https://www.sparesbox.com.au/blog/normal-cabin-filter-carbon-activated-filter

Your Air con runs on R134a refrigerant and it is a sealed system. It doesn't put "gas" into the air stream. If it had developed a leak, it would've vented out already and all the connection points are in the engine bay, not inside the cabin. Besides, R134a doesn't have an odour which you describe anyway.

If you have contamination inside your return air box, behind the glovebox, then yes, it's possible it will purge dirty air into the cabin. You need to drop the glove box lid down and inspect the condition of the filter.

I find it hard to believe it could be coming from anywhere else besides what I described earlier and this.

 

Edited June 18, 2021 by Tony Prodigy

[campbeam]

You may find this YouTube video by The Car Nut of some interest. I am guilty of doing this so trying to wean myself away from this "bad habit". I have also had a bad petrol smell in the car so a bit of an incentive to mend my ways before it results in a repair bill.

 

[Tony Prodigy]

Good thought Ash. I do remember watching that video some time back because I was also one of those guys. Now I stop adding fuel as soon as the trigger stops.

Is it possible the O.P then may have a saturated evap system ? He reckons it smells like LPG though. That's way different to unleaded. This is really a weird one.

I guess O.P can tell us if he is also guilty of overfilling his tank too.

[SkylineAurion]

On 6/19/2021 at 8:04 AM, Tony Prodigy said:

Forgot to address this in my previous post. If you suspect the smell is coming from the A/C, then it's probably that. When you start to smell, I'd pull over and put your nose to the vent while it's blowing to see if it is. It's possible you cabin filter could be contaminated and the smell is coming from this. I upgraded my cabin filter to the charcoal activated type to help filter out engine fumes, smoke etc.

https://www.sparesbox.com.au/blog/normal-cabin-filter-carbon-activated-filter

Your Air con runs on R134a refrigerant and it is a sealed system. It doesn't put "gas" into the air stream. If it had developed a leak, it would've vented out already and all the connection points are in the engine bay, not inside the cabin. Besides, R134a doesn't have an odour which you describe anyway.

If you have contamination inside your return air box, behind the glovebox, then yes, it's possible it will purge dirty air into the cabin. You need to drop the glove box lid down and inspect the condition of the filter.

I find it hard to believe it could be coming from anywhere else besides what I described earlier and this.

 

Hey mate I ordered the cabin filter and I’m waiting for it to arrive. Do you know what part number my 2008 aurion atx 3.5L petrol 2gr-fe uses for the fuel filter?Is it z708? Like a in-tank fuel filter? If so why do they make it difficult and not put those standard cylinder type fuel filters with an entry and exit in the engine bay for ease of access and replacement? Cheers

[Tony Prodigy]

28 minutes ago, SkylineAurion said:

Do you know what part number my 2008 aurion atx 3.5L petrol 2gr-fe uses for the fuel filter?Is it z708? Like a in-tank fuel filter? If so why do they make it difficult and not put those standard cylinder type fuel filters with an entry and exit in the engine bay for ease of access and replacement?

Unfortunately the fuel filter/pump assembly is one unit and is in the tank. You have to remove the base of the rear seat and unscrew the access hatch to get access to the assembly unit. There are plenty of DIY youtube videos you can learn from on how to remove-disassemble and re assemble.

Found these for you on Ebay.

This or this. 

Both will serve you well.

[SkylineAurion]

3 hours ago, Tony Prodigy said:

Unfortunately the fuel filter/pump assembly is one unit and is in the tank. You have to remove the base of the rear seat and unscrew the access hatch to get access to the assembly unit. There are plenty of DIY youtube videos you can learn from on how to remove-disassemble and re assemble.

Found these for you on Ebay.

This or this. 

Both will serve you well.

Aren’t these ones the correct ones(from what I’ve gathered). They look different to the ones you provided

https://www.ebay.com.au/itm/274830542508

[campbeam]

The Z646 was a direct replacement for my Oct. 2006 Aurion ATX. I would expect this part to fit your 2008 Aurion ATX.

The Z708 filter is more likely to fit later year 40 series Aurions. 

Suppliers should be able to confirm from the VIN which part is applicable. Alternatively, remove the back seat and have a look at the fuel filter. 

[Tony Prodigy]

7 minutes ago, campbeam said:

Suppliers should be able to confirm from the VIN which part is applicable. Alternatively, remove the back seat and have a look at the fuel filter. 

 

2 hours ago, SkylineAurion said:

Aren’t these ones the correct ones(from what I’ve gathered). They look different to the ones you provided

https://www.ebay.com.au/itm/274830542508

Do what Ash suggested. Send your VIN to the supplier and just confirm. All those listed should fit ok even though one may look different to the other. There is some disassembly required of the fuel filter housing. You will need to swap over the fuel pump from your original housing and clip it all back together. The Z646 is just the filter section. You will need to attach all your other ancillary pieces to it. If you have time tomorrow, try and pull it out to inspect it. Get a few photos for reference. Also, the Z646 is also said to go from 2006 right up to 2011. Same should go for the Coopers one too. I know the Z708 looks different. It just has all the extra bits you don't really need. But best to pull yours and see. It is possible that Toyota did use two styles during production, but I can't confirm this.

 

[ZZT86]

@SkylineAurion  My Aurion takes 1 second to start, cold or hot. Have you plugged in an OBD scan guage to confirm all is healthy with electrics & fuel system ? Sounds like you may have a fouled O2 sensor when you start it cold, but you say it runs fine ?

[SkylineAurion]

On 7/2/2021 at 11:17 PM, ZZT86 said:

@SkylineAurion  My Aurion takes 1 second to start, cold or hot. Have you plugged in an OBD scan guage to confirm all is healthy with electrics & fuel system ? Sounds like you may have a fouled O2 sensor when you start it cold, but you say it runs fine ?

Nah mate I got it sorted after changing the fuel filter. Starts up in a second now.

I changed the cabin filter too to get rid of that gas smell I was mentioning earlier but the smell still comes up time to time when I’m driving hard. Look how filthy the cabin filter was

 

[Tony Prodigy]

7 minutes ago, SkylineAurion said:

Nah mate I got it sorted after changing the fuel filter. Starts up in a second now.

Was the gasket not sealing correctly on the sender unit ? Still not sure why you'd smell petrol unless the gasket was compromised somehow.

That cabin filter looks nasty too. Plenty of microbial action going in there for sure.

[ZZT86]

Struth 😱  Something I do more often these days is change out that filter right there more often. Easy to inspect/replace & better quality air that you & your loved ones breath 😉

Glad you sorted the fueling hesitation. Was it the first fuel filter change ? What was the condition of filter ?

[SkylineAurion]

2 hours ago, Tony Prodigy said:

Was the gasket not sealing correctly on the sender unit ? Still not sure why you'd smell petrol unless the gasket was compromised somehow.

That cabin filter looks nasty too. Plenty of microbial action going in there for sure.

Are you talking about the largest rubber o ring on top of the fuel pump/filter assembly? It seemed fine, not brittle or cracking. From what I remember it was sitting a tiny bit above the metal flooring . Is it meant to sit perfectly flush? Also it’s not a petrol smell. Petrol has a distinctive smell to it, it’s a smell like LPG, I cannot be more clearer than that.

I just had a look at the video that I followed to change the filter and it does seem the whole assembly sits just right above the metal flooring and not flush . Refer to the pic

Also one more thing, I was just reading the comments on the video and he mentioned he used gas to lubricate the o rings in the assembly, I thought it was engine oil so I used that instead. How f**ked am I?

2 hours ago, ZZT86 said:

Struth 😱  Something I do more often these days is change out that filter right there more often. Easy to inspect/replace & better quality air that you & your loved ones breath 😉

Glad you sorted the fueling hesitation. Was it the first fuel filter change ? What was the condition of filter ?

i only changed the fuel filter, not the pump or anything else. And it’s the first time I changed it since I bought nearly two years ago. Don’t know the condition of the filter, I didn’t cut the fuel filter in half to inspect it

Edited July 16, 2021 by SkylineAurion

[Tony Prodigy]

1 hour ago, SkylineAurion said:

Are you talking about the largest rubber o ring on top of the fuel pump/filter assembly? It seemed fine, not brittle or cracking. From what I remember it was sitting a tiny bit above the metal flooring . Is it meant to sit perfectly flush? Also it’s not a petrol smell. Petrol has a distinctive smell to it, it’s a smell like LPG, I cannot be more clearer than that.

 Sorry, yes I recall you saying it was an LPG smell now. I thought it was a petrol smell and if the seal isn't doing its job then yes you could get fumes wafting in. My friend had the recall done on his 2018 Camry (it was a fuel pump related issue) and the Jackass who did the job at Toyota didn't put the gasket right and the car wreaked of petrol. When his mum asked me to check it out I told her straight out to take it back to Toyota because I had a strong feeling the guy never put the sender back in properly. They got it sorted. A new gasket was installed. It's more of a gasket not an O-Ring. It lifts out with the sender/pump assembly.

It's not supposed to sit flush as it sits on the gasket, then the black metal cover puts a downward force on the assembly as you tighten the screws. Just need to make sure the unit is in the right way and the gasket is correctly positioned then you put the screws back down. Your picture indicates that you did it correctly.

1 hour ago, SkylineAurion said:

Also one more thing, I was just reading the comments on the video and he mentioned he used gas to lubricate the o rings in the assembly, I thought it was engine oil so I used that instead. How f**ked am I?

You don't need to lubricate the rubber seal. Just make sure it's clean and dry. It is quite a thick rubber gasket and it will seal perfectly well once clamped down. It will form a tight seal no worries. 

You did good. It is a fiddly job but is achievable if you have patience and take your time. I recently had mine out to inspect and replace but it turned out they sent me the wrong part so I had to reassemble it all back together and refit it. I did get to clean the intake sock at the pump inlet though. Those can get clogged with very fine debris from the crappy fuel we get in Sydney. Gave it a good flush through with brake cleaner. You can also use carb cleaner too.

Here are some pics of mine.

( the new site update is a little retarded- it's uploaded my photos in the reverse order. Arrghh !)

Edited July 16, 2021 by Tony Prodigy

[SkylineAurion]

44 minutes ago, Tony Prodigy said:

 

I was actually going to buy the filter like the one in your pic, but in the earlier replies you Told me to get the z646 instead and I did, it was the correct one. If I bought the one like yours then all that would’ve taken way more time then excepted, with the removal and installation. So thanks a lot for that

and when I was talking about lubricating the gaskets, I don’t mean just the big one that sits on top, I applied engine oil to the smaller o ring gaskets inside the fuel pump and filter assembly. Their was quite a few small ones. I only applied very little though. I’m concerned the engine oil will contaminate the fuel and cause problems within the assembly and to the engine. What do you think?

also if I knew about that sock I would’ve cleaned that too but I guess it’s too late now 

Edited July 16, 2021 by SkylineAurion

[Tony Prodigy]

4 minutes ago, SkylineAurion said:

I was actually going to buy the filter like the one in your pic, but in the earlier replies you Told me to get the z646 instead and I did, it was the correct one. If I bought the one like yours then all that would’ve taken way more time then excepted, with the removal and installation. So thanks a lot for that

and when I was talking about lubricating the gaskets, I don’t mean just the big one that sits on top, I applied engine oil to the smaller o ring gaskets inside the fuel pump and filter assembly. Their was quite a few small ones. I only applied very little though. I’m concerned the engine oil will contaminate the fuel and cause problems within the assembly and to the engine. What do you think?

also if I knew about that sock I would’ve cleaned that too but I guess it’s too late now 

Hmm, I'm looking at your pump assembly and you say you have a 40 series Aurion right ? Cos that there looks like one from the 50 series which has a taller-skinnier filter section. The 40 series ones are shorter but fatter which is why I suggested the Z646. I'm baffled now because you say it was correct but the picture there looks a lot like a 50 series setup. I learned this after purchasing what I believed was the correct filter for my 50 but turned out that it was in fact for the 40 despite the stupid listing in Ebay saying it would fit. 

I see what you mean now regarding the O-Rings. Typically no lubrication is required if you're re using the existing ones but if they are new perhaps a little WD40 spray could help seat them in. You should be ok with what little motor oil you used. It will just wash away no harm done.

Here are some pics of the two filters side by side. The seller let me keep the 40 series one and when I purchased the "correct" 50 series one I did a photo shoot to compare the two.

The left one in the pic is for the 40 series. To the right is the 50.

 

 

 

 

The Blackened Filter Sock Before Cleaning.

 

[SkylineAurion]

10 minutes ago, Tony Prodigy said:

Hmm, I'm looking at your pump assembly and you say you have a 40 series Aurion right ? Cos that there looks like one from the 50 series which has a taller-skinnier filter section. The 40 series ones are shorter but fatter which is why I suggested the Z646. I'm baffled now because you say it was correct but the picture there looks a lot like a 50 series setup. I learned this after purchasing what I believed was the correct filter for my 50 but turned out that it was in fact for the 40 despite the stupid listing in Ebay saying it would fit. 

I see what you mean now regarding the O-Rings. Typically no lubrication is required if you're re using the existing ones but if they are new perhaps a little WD40 spray could help seat them in. You should be ok with what little motor oil you used. It will just wash away no harm done.

Here are some pics of the two filters side by side. The seller let me keep the 40 series one and when I purchased the "correct" 50 series one I did a photo shoot to compare the two.

The left one in the pic is for the 40 series. To the right is the 50.

 

 

 

 

The Blackened Filter Sock Before Cleaning.

 

I’m so confused now too. Cos initially I was going to buy the z708, like your one, because I read that it was the correct one. but for some reason you told me to get the z646 instead for some reason and I’m glad you did otherwise I would be stuck with the z708 that doesn’t fit, not to mention all the effort of pulling apart and putting it all back together and realising it’s the wrong part. And yes it’s a 2008 xv40. Here is the pic of exact filter I bought. Once again thanks for preventing all the unnecessary headaches lol

 

[Tony Prodigy]

11 hours ago, SkylineAurion said:

I’m so confused now too. Cos initially I was going to buy the z708, like your one, because I read that it was the correct one. but for some reason you told me to get the z646 instead for some reason and I’m glad you did otherwise I would be stuck with the z708 that doesn’t fit, not to mention all the effort of pulling apart and putting it all back together and realising it’s the wrong part. And yes it’s a 2008 xv40. Here is the pic of exact filter I bought. Once again thanks for preventing all the unnecessary headaches lol

 

 

IMG_2039.MOV

I had to go back and refresh my memory. It is very easy to get confused with these because there is a lot of misinformation out there, even Ryco themselves have made a blunder of it as I discovered. It has been some time since I had to visit this and believe me, I found out the harder way.
 

If you look at this link for Ryco, It has all the filters listed for both the 40 and 50 series Aurion right ? But, if you look closely at the fuel filter section, they list TWO fuel filters for the GSV-40R and NONE** for the GSV-50R. 

They list the Z646 & the Z708. Well, the Z708 is wrong. It doesn't fit 40 series Aurions. It is actually for the ACV40R Camry with the 2AZ-FE 4cyl engine. 

The Z646 also fits ACV36 Camry's V6 and 4cyl, 1MZ-FE and 2AZ-FE respectively. You have to purchase based on the platform more so than the engine. 

**Now, for the best part. If you notice on the Ryco page, there is no reference for a 50 series fuel filter because Ryco don't make one for it. The only aftermarket company that does is Wesfil/Coopers. It seems they have the exclusive rights by Toyota to manufacture it and nobody else. Go figure... So off I went in search of the Wesfil part and found it to be the WCF-364. It was either this or Genuine Toyota and nearly $200 thanks for coming.

So you see, when I advised you to get the Z646, I knew it was the right part for your car, but looking at your photos in the latter stages confused me a little in that I forgot what it looked like. It has a similar dimension to the fuel filter section of the WCF-364 but the rest of it is completely different. So my apologies if I confused you. The WCF-364 assembly encompasses not only the fuel filter section but the sender top hat. Your Z646 is just the fuel filter section. Both need disassembly, of course, but they do differ in some respects.

Those photos I uploaded comparing both filters, the one on the left was a Z708 which looks similar to the WCF-364 but the filter section is shorter and fatter AND is meant for the Camry 40 series. The seller who listed it on Ebay made a mistake and I had to find out the hard way. That was what sparked my interest to investigate a bit further. If you go on Ebay and search up fuel filter for a 50 series Aurion, you will be astounded how many dopey sellers are still selling the Z708 saying it will fit the 50 series and 40 series. It won't.

I hope this helps clarify the situation. Now that you and others know, it will help decision making in the future.

All the best mate 

 

[Twixter]

Heyo. Just jumped in for the point about the smell of fuel or the rotten-egg like smell when you accelerate hard. Could be a faulty CAT converter.

 

My car has done it since I owned it 2years ago. Wind the windows down whenever you do something like pushing the car hard, then wind them back up after about a minute. It'll clear the smell out. I think I have a hole in my boot somewhere where the exhaust is coming up into the cabin, but I'm not sure. I've spoken to a few other Aurion owners who get the same thing. (usually when merging onto a HWY and you **** belt the Aurio, that sort of driving)

 

I've been told by an exhaust technician that it's the fuel slowly seeping through the cat converter and that's what you're smelling in the exhaust. Since Sulfur is present in petrol today you can smell it once it passes through an older (or faulty) cat converter. He said it's nothing serious as long as you wind a window down every once in a while, or turn the air-con on. As for how true any of that is, I have no idea...

 https://www.700r4transmissionhq.com/toyota-aurion-rotten-egg-smell/#:~:text=If you happen to smell,of the sulfur in gasoline. (this article also mentions about sulfur content in fuel mixtures)

 

Another toyotaownersclub member made a post about this specific topic already too: