I can smell exhaust when driving and the engine is under load, for instance when going uphill on the freeway. I have the original stock exhaust and cat, 100K miles.
This only seems to happen in such situations. My suspicion is obviously some exhaust leak, just don't know why would it happen only in these cases, and also unsure how the gases get into the cabin. Any idea how should I approach this, and can this be a signal of some other, maybe bigger problem?

Thanks.

 

More noticeable when windows are open or closed? How about if HVAC is on recirculate?

 

Windows are closed, don't remember having them open on that stretch of road when I smelled the exhaust. I rarely use the recirc mode, but will have to try if it makes a difference.

 

If you're smelling it with the windows are closed and the HVAC is in recirc then you've got a pretty serious exhaust leak.

The fact that you're smelling it at highway speed is odd to me because the air rushing over the car should be blowing most of it away pretty quickly. Could it simply be that you're getting exhaust odor from cars ahead of you?

 

It is definitely not from other cars in front of me because I smelled this a few times even when there was no other car around.

I tried it today with re-circulation mode and windows up, and there was no smell. So somehow the odor gets into the vent system - but why only when the engine is under load? Strange.

 

Usually there is some lag from when a smell is generated outside the car to when it makes its way through the vents.

Is it possible it's happening when you're stationary but you're only noticing it when you take off?

Also, are you certain it's exhaust and not burning oil smell? (I know these are basic questions but some people make that mistake and your situation is odd)

 

I can only notice it in a situation like I described. Otherwise nothing.

Yes, I'm sure it is the exhaust, since I know how that is when standing next to my car with a running, idle and not fully warmed up engine

I agree, this is a rather odd issue. Perhaps I shouldn't think too much of it - but I'm quite particular about maintenance and any unusual things with my car.

 

If you have a leak under the rear of the car...and the trunk vents are stuck open a bit you can get exhaust sucked into the trunk

you can also get exhaust smell if your shifter rubber bushing is ripped and it can leak in around the shifter

 

Hmm, thanks - I never heard about trunk vents though and how those could be stuck open.
I'll check the shifter bushing to see whether it's torn. The funny thing is still why is there only smell when going uphill? I'd think if there is a leak, then I would smell the exhaust more often and not only in this specific scenario.

 

I think the fact that you don't notice the smell when the HVAC is on recirc means it's probably being pumped in by the HVAC blower rather than diffusing through the trunk vents or shifter boot.

The fact that it only happens under load makes me think that it's only when the driveline is hunched slightly.

When under load, the whole engine and gearbox will twist ever so slightly on it's mounts. That means that the engine is putting stress on the exhaust manifold which is torquing the cat/midpipe and on down the rest of the exhaust. Maybe it's fine at low/no load because it's this twisting motion that's opening up the leak.

I would check the bolts and gasket between the cat/midpipe and exhaust manifold. Maybe they just need to be torqued down.

 

Thank you, this sounds very reasonable.
Based on this theory, it may even be that I should look at my engine mounts (or tranny mounts too), since if they have a problem, that would probably allow more movement in this situation. Actually my mounts are still the original ones, and after 100K miles, I suppose this could also contribute.

 

I also got the same issue, only happening when I rev to redline, I always get that burning exhaust fumes in my cabin (HVAC circulated or not).

 

I tend to get an exhaust smell once in awhile too. Mine usually happens when I come to stop with the HVAC in regular mode. If I keep it in recirculate, I never have an issue. I believe I have a small leak where the manifold bolts to the converter.

A few months ago I bought a nice Felpro replacement gasket, once it warms up I'm going to install it.

How much if any are you premixing? If your mixing heavily that will definitely give you a strong exhaust smell.

 

I'm not premixing at all. Got this problem since I bought this car, some burned smell when I go to redline.
Now I installed BHR midpipe, but the smell is still the same, not getting stronger, but still a burned smell when going to redline.
I also can smell my exhaust gas when the window is down.
I think I'll visit my local workshop to have this issue checked. Now my mom hates my car because of the interior smell.

Also got P0101 and P0172 today

 

Well your codes go hand in hand with each other, you need to check your MAF sensor. When was the last time you have cleaned it?

P0172 indicates a rich fuel mixture

P0101 indicates a issue with your MAF

Fixing your trouble codes will greatly reduce the fuel stench your complaining about. Keep in mind, running without a cat will cause your exhaust to have a fuel odor to some degree.

HTH

 

Did you use new gaskets when installing the BHR midpipe? If not, do so.

Have you gone back and re-torqued the fasteners? The heat/cool cycle can cause them to loosen up a bit.

For your codes, check out the FSM here.
Click "Engine" and then click the first link ("Onboard Diagnostic...").

First thing you should do though is clean your MAF. Get some MAF cleaner at an auto parts store. Electronics cleaner spray can work in a pinch but I wouldn't chance it. Under no circumstances should you use anything else to clean your MAF. It's easy to do and has a slim chance of solving your problem.

Beyond that, you should start a new thread about your P-codes.

 

Never cleaned it just bought that car with 41k KM on it.

Yes we used the new gasket provided in the package, I don't do it by myself though, because I don't have the necessary tools (thinking about buying some, so one day I can do some simple stuffs on my own).
Thanks for the suggestion, I'll try clearing the MAF sensor first.

Sorry for being OOT.

Back to topic, did anybody has a clear pics (or point me) where is the trunk's vents location? After reading some threads here, I'm thinking that stuffs being stuck might be the culprit for the exhaust fumes entering the cabin.

 

I wasn't able to find photos on these on the RX-8 but here are a few from other cars. They're in the same approximate locations.

Piston Slap: Truncated Thoughts on Trunk Vents
https://2.bp.blogspot.com/_BC-CC9cI2..._trunkvent.jpg

 

thanks a lottt!!