Jwconeil

I noticed that my ISF smells of exhaust. I don’t have cats, so it is expected. I think the smell intensifies while using the climate control. Is that just the nature of no cats, or the headers leaking?

lexicon72

I've got PPE headers and no cats and only get the exhaust smell when I come to a stop and the windows are down.
Two common culprits are the vents in the trunk failing or a header/exhaust leak. Sounds like the latter to me. Good luck.

av8or

Try this.. https://www.clublexus.com/forums/is-...ot-solved.html

you can close one and buy a new flap for the other. Or replace both.

Jwconeil

I actually just read that thread. Makes a lot of sense. I have always had a lot of exhaust smell, it just seems worse... but I also always have the windows down and it’s too cold to do that right now. I’m going to permanently seal both vents and see how it goes. That’s a terrible design with the exhaust tips behind the bumper. It may just be time to put some real tips on this car as well. After looking at that flacid, thin flap, there is no way even a new one would be air tight to exhaust ingress.

Yri

That design about the tips being behind the bumper is stupid... lol

Rickna

iTrader: (3)

I'm not so sure about sealing both vents. I read somewhere on here CL that in the hot months the vents allow the expanded air to be released from the cabin. With both vents blocked the sunroof can shatter. I know it sounds far-fetched, if you think about it...

Jwconeil

It does sound very far fetched to me. I’ve had numerous cars without vents in the trunk, and a car is not air tight anywhere. If you block those vents and sink the car in water, it’ll still fill up at essentially every joint. Air is even more permeable than water.

I appreciate the tip, but that post is not based on sound reasoning, but conjecture. Cars are simply not air tight. With the design of the exhaust, I’m surprised they let this thin flap be the only thing that protects occupants from exhaust gasses. That being said, If blocking the vents works, I’ll consider extending the exhaust after the season anyway. Those fumes can creep into the car in other places.

Plus, I’d rather eat crow than exhaust fumes.

av8or

DO NOT SEAL BOTH. I did that at first and noticed it was harder to close the trunk as air needs to go out somewhere as it is compressed. And yes you might shatter your windows in the process if you shut your trunk forcefully. I ended up sealing the pax side and bought a new one for the driver

ISFpowered

Definitely check your trunk vents. Mine were broken and dry rotted. Also check to see if where your headers connect to your exhaust leaks. Mine was from the gasket, it was covered it black soot. Fixed both and no smell even with the windows down it takes a long time to for you to start smelling it.

iH8RICERZ

iTrader: (4)

hrmm, i should probably try out this out. Ever since I got my PPE's installed, the exhaust smell is really bad when my windows are down. I even went and got high flow cats installed to hopefully make it bearable but I have to leave the windows closed all the time now. Had my exhausted tightened and checked, so I'm assuming those stupid vents are gone to a point where they aren't really doing their job.

lobuxracer

iTrader: (2)

And I still hear mine go thunk when I close the door on the car. Weird.

2008ISF

iTrader: (1)

I started with the original JoeZ exhaust (version 1 with mufflers sitting behind the bumper) with the stock headers, and dry rotted rear trunk vents. No noticeable “smell”. That doesn’t mean dangerous/harmful fumes weren’t getting into the car...I just couldn’t “smell” them.

Then I added PPE headers to the system. Just driving the car with the windows up and sunroof closed, it didn’t smell too bad. When the sunroof was open, or the windows were open, or both the windows and sunroof were open at the same time, the car would reek terribly.

i bought the Joe Z mufflers that extend through the bumper and taped up both rear trunk vents and the smell is gone.

I haven’t had any ac, moisture, condensation, heating, sunroof shattering, or air pressure issues to speak of yet. Doesn’t mean I won’t in the future. Also, trunk and doors are easy to close.

Also, with the vents closed up, I don’t get any more dirt, debris, rocks, or foreign material getting all over my ML amp and carpeting.

Jwconeil

Some people here really must believe cars are air tight. They aren’t.

I spent the last year chasing an O2 related code, and had the system thoroughly checked then for leaks. I fixed the header to exhaust leak, and we found no more (turned out to be the O2 eliminator). So unless a new leak has developed, the likely culprit is the trunk vents. I’ll seal them tight tonight and see if the smell goes away.

Are there any bolt on exhaust tips that fit our cars. I couldn’t really locate an answer on this through searching. My kids are in my back seat often during summers, so I’ll fix it correctly by putting the exhaust where it belongs.

JWarr00

It's not that, more when closing a door or the trunk, there is a large enough pressure change that the many, slim, non-air-tight crevices don't compensate accordingly, and you are met with resistance. Otherwise why would there be vent flaps at all?

Also FWIW, like Lobux, I hear my flaps clapping when I shut the doors, it's an '08.

av8or

👍 correct.. try closing both flaps and then close your trunk. Take a look at your windows while doing so. You will see the pressure pushing them like they are going to break. That is why I left one open with a new flap after initially closing both with tape..