Help! My 2006 cdi Exhaust Stinks and Chokes me out!

[Smart4two 4]

No visible smoke coming from the car. I can not start the car and sit still without being chocked out inside with the nasty exhaust smell! Windows are up. The air around the car and 30 feet away will be saturated with the nasty exhaust smell if I start the car and let idle for 10 minutes. I have to shut the heater fan off at stop lights or the exhaust gets sucked in!

[MikeT 744]

Try shutting the external air intake off when stopped. Also: idling for ten minutes? Why?

[Smart4two 4]

Only did the 10 minute idling thing a few times to warm the car up in frigid weather. Not worth is though if I get gassed to death! I shut the heater fan off when stopped at a traffic light. Cold weather here. Usually can't sit and idle in parking lot to keep warm. Is this deadly exhaust gas normal for these 💩 boxes?

[Mjolinor 91]

They normally only get engine fumes inside if you do not have the engine hatch fastened down.

 

 

[Smart4two 4]

Hatch is snug. I'll have to get underneath while it's running in an attempt to figure it out.

[Willys 747]

Maybe your CATT is semi plugged?   I do know, don't ask me how I know, that if you don't have a working or present CATT installed the car will stink when idling at a light or when you first start it up. Far more than a normal engine would.   OR perhaps it's the opposite and your exhaust is plugged just enough at low RPMs that it has trouble clearing the fumes? What setting do you have your air intake set at? Outside or internally? Does it happen at all times when siting or just sometimes? Could be just the fact the exhaust gases can't escape from under your car while sitting in certain locations..???  Just a shot in the dark so to speak??  Does your car blow any smoke normally? Blue or white?  Does it do it once engine is warm or hot or just cold?

 

[tolsen 630]

I wonder if some unSmart previous owner has cut a hole in rear of floor to access starter like one or two members here once did. That would certainly make the cabin stink. 

[Smart4two 4]

12 hours ago, Willys said:

Maybe your CATT is semi plugged?   I do know, don't ask me how I know, that if you don't have a working or present CATT installed the car will stink when idling at a light or when you first start it up. Far more than a normal engine would.   OR perhaps it's the opposite and your exhaust is plugged just enough at low RPMs that it has trouble clearing the fumes? What setting do you have your air intake set at? Outside or internally? Does it happen at all times when siting or just sometimes? Could be just the fact the exhaust gases can't escape from under your car while sitting in certain locations..???  Just a shot in the dark so to speak??  Does your car blow any smoke normally? Blue or white?  Does it do it once engine is warm or hot or just cold?

 

 

I think the Catt could be the problem now that you mention it. Sometimes I forget to shut fan off at traffic light and no stink. I figure the wind is blowing it away. Other times I forget to shut fan down and it stinks! I would guess the intake is set to outside. I'm not sure how to set it though. Car blows no smoke.   No holes cut in floor that are letting the exhaust in!

[MikeT 744]

21 hours ago, Smart4two said:

(1) Only did the 10 minute idling thing a few times to warm the car up in frigid weather. Not worth is though if I get gassed to death!

(2) I shut the heater fan off when stopped at a traffic light.

(3) Is this deadly exhaust gas normal for these 💩 boxes?

(1) If it's a 2006, plug in the block heater. The car burns so little fuel at idle that it barely warms at all and it's terrible for the engine.

(2) better to leave it on, and shut the outside air off. Opposite side from the fan control.

(3) for yours, it seems. They do smell compared to a gasoline engine's fumes.

 

[Smart4two 4]

I have some cardboard blocking the rad right now. it's about 3 inches away from rad so air can still get through it. Warms up much quicker driving down the road. Have device plugged in that gives me the engine temperature when it's running.

[Willys 747]

10 hours ago, Smart4two said:

I have some cardboard blocking the rad right now. it's about 3 inches away from rad so air can still get through it. Warms up much quicker driving down the road

I also block 9/10th of my rad during the winter months....and never gets the temp above 3 blobs even while sitting in traffic or idling. I also never get heat from my engine while idling. It needs to be worked as in low down RPMs to get real heat from this engine. Keeping the engine in the power band doesn't result in better heat, just better performance. My engine gets the best fuel economy at as close to 1950 rpms in 6th gear. I tend to watch the scangaugeII a lot when driving as it is my mission to see how low I can get that magical LPH driven. I can easily average 3.5 which also gets the temps to easily stay at the 3 blob area.  IF I sit and idle the temps go down and so does the inside heat. I also run concistantly pulling from the outside in....or because of wet carpeting either from leaks, which I think I have solved or wet boots etc, the windshield will fog from condensation.
My car does smell when idling at a light or when I first start it, as it's getting over 250,000km it is now smoking well at start up. 

You could also check your rear hatch seal, door and window....unless it's a soft top..?

[Smart4two 4]

It's hard top. Temp also stays at 3 on mine. Plugged cat maybe. Exhaust got real noxious when winter rolled around last year.

[MikeT 744]

Not likely a plugged catalyst. An Italian tuneup up the Coq at 4200 rpm would clear that out pronto.

[Willys 747]

Could always open up exhaust from the forward facing side and surgically remove the cat and weld back together...? So if it gets looked at it isn't easily visible.  I know someone who has done a few...wink wink...so I heard...lol.

 

What is the condition of your exhaust any way? Is it like new or has it developed the usual split lower seal that dumps out the gases under the car and not pushed through exhaust pipe away from vehicle?  I weld up that broken seam, it's not always possible but most can be repaired to last a few more years at least.  The body of the exhaust is made up from 3 layers of paper thin metal which makes it almost impossible to weld unless you own a commercial grade welder. It must be turned down very low to be able to weld such thing material and even then it's tricky.

Edited March 23, 2023 by Willys

[smart142 605]

Behind the rear panels are 2 large plastic plugs in the body below the tailgate. They often weather and disintegrate, The opening would allow exhaust fumes to enter the car.

[Smart4two 4]

2 hours ago, smart142 said:

Behind the rear panels are 2 large plastic plugs in the body below the tailgate. They often weather and disintegrate, The opening would allow exhaust fumes to enter the car.

 

Thanks. I'll check that.

[Smart4two 4]

10 hours ago, Willys said:

Could always open up exhaust from the forward facing side and surgically remove the cat and weld back together...? So if it gets looked at it isn't easily visible.  I know someone who has done a few...wink wink...so I heard...lol.

 

What is the condition of your exhaust any way? Is it like new or has it developed the usual split lower seal that dumps out the gases under the car and not pushed through exhaust pipe away from vehicle?  I weld up that broken seam, it's not always possible but most can be repaired to last a few more years at least.  The body of the exhaust is made up from 3 layers of paper thin metal which makes it almost impossible to weld unless you own a commercial grade welder. It must be turned down very low to be able to weld such thing material and even then it's tricky.

 

Surgery on the cat sounds intriguing. Leaking exhaust could be a possibility. Have not done a close inspection yet. I think the tailpipe needs to be extended a bit.

Edited March 23, 2023 by Smart4two

[MikeT 744]

Just note that removing the cat will result in more particulates (probably up to 90% more based upon the claimed efficiency) and therefore more stink.

Edited March 24, 2023 by MikeT

[Smart4two 4]

13 minutes ago, MikeT said:

Just note that removing the cat will result in more particulates (probably up to 90% more based upon the claimed efficiency) and therefore more stink.

 

I'm thinking it could be busted up inside and causing the stink. Might cut it open to Check. Will check for muffler leaks 1st. The exhaust might be saturating under the car.

[MikeT 744]

Possible.... but if it's not rattling, unlikely.

[Willys 747]

Removing the cat will make your car smell while idling and not moving, period. As soon as you move that smell disappears completely. So for the few times you sit stationary the bad effects imho are worth the better flow from removing the cat, to each their own as per how many years this will take from the planet's life span...lol.  Once you see inside the muffler you will see how restricting the cat is, you can hardly see through it the holes are so small. I couldn't find anything thin enough to clean the passage ways to get better flow, or even regain what it had from stock.  I have also seen mufflers so plugged up with soot that it took a long time to beat the debris out of the muffler before I could repair it.

The whole thought process when asking about better performance with such small engines is will any one mod make any difference that you will definately notice, it has to be many small mods added together to generate enough of a difference to get real "HP" numbers, so to speak.  That is IF you are actually chasing this stupid HP thing in a .8 lt 3 cylinder water pump of an engine...lol.  Yes I sort of am one of these people. I just like doing everything you can to make things work better if possible, right or wrong....to each their own.

 

The usual damage to your muffler will be the bottom seam will be rusted which will open up the muffler and allow the gases to sit under the vehicle rather than be pushed away by the tail pipe. Welding the seal back up either by cleaning the mating surfaces and bringing them together well enough to even capable to be welded or adding a plate after removing all the rusted metal and welding the plate along the bottom of the muffler.  Either way is a time consuming battle of not blowing through the extremely thin material.  It takes me over an hour to do a simple repair if the rust isn't too bad, many hours to repair one needing a plate.  But it's far cheaper than buying a new stock muffler. Price one out.  OUCH....!!!!
You could also if you have some welding fabrication talent, convert a motorcycle muffler from a far larger cc'd engine like a 1000cc bike like I have done as it gets you a muffler without any seams and also no cat internally. I used a Honda CB1000rr muffler which was a new take off.  Again to each their own.  My muffler is slightly louder but not by much at all. Definately  worth doing it if you are worried about the noise levels. I didn't change any internals of the bike muffler just the intake pipe and exiting pipe I made into a dual pipe not a single.

[MikeT 744]

I have a benchmark for my car's performance. A steady 7% slope that the car will pull 115 km/h on if starting at the bottom at 90. Since installing the BRABUS dual exhaust, with its cat still intact, the car's speed up that slope has not varied between 40,000 km and 170,000 km. So the BRABUS dual exhaust at least does not have a restrictive catalyst. And this with a rich fuel remap.

 

I never noticed a depreciation in performance of my first cdi either which had stock exhaust and map. But, and this is important, the car was driven briskly regularly, like steady 4000 RPM up steady hills for 2-20 minutes (easy here in BC) and that is what superheats the honeycomb and burns off all the carbon.

 

I think city driven and gently driven cars will have a problem not only with cats but also EGR. The first smart never had an EGR issue in 247,274 km.

Edited March 25, 2023 by MikeT

[Smart4two 4]

Found a bunch of good pictures of the muffler cut open on a google search. Cold days here so will tackle exhaust on a warmer day. Car runs OK so no rush on getting to it. The lever for the air intake for heater broke off 3 months ago. Used the end of a plastic for to move it to the recirculate position. Should be able to keep the heater on at traffic lights now!

Edited March 25, 2023 by Smart4two

[Willys 747]

9 hours ago, MikeT said:

think city driven and gently driven cars will have a problem not only with cats but also EGR.

I agree with this, but it ruins the great fuel economy I get...lol....IF you are after fuel economy then you also have to drive it accordingly which usually means no performace type spurts...which is what is needed to clean out your cat. Just bring back the dirty 60-70's....lol.  But also bring back the price of fuel...lol.  

You can't have both worlds, you either choose economy or fun...to each their own.

[MikeT 744]

Even driving the way I do, with the remap, wide tires, open convertible top half the time etc, the lifetime average is 4.19 L/100. The other smart I had averaged 3.95 L/100, which is good enough for me!

Edited March 25, 2023 by MikeT