Z4m Exhaust Gas Smell

tshammas · Post by **tshammas** » Wed Sep 19, 2018 6:56 pm

Hi guys,

My z4m is giving a very strong exhaust smell from the exhaust pipes which burns the eyes.

I have checked the car for errors and nothing shows up. Has anybody faced this issue before as I heard this tends to happen to older bmws.

Any help would be appreciated!!

ga41 · Post by **ga41** » Mon Sep 24, 2018 4:04 pm

I had this when my O2 (lambda) sensors failed which then caused the catalytic converters to disintegrate.

I'd check the sensors even though no fault codes. I'd take it to a good mechanic and have them checked with a multimeter. And have a look at your catalytic converters too because sustained running with rich fuel will ruin them... When I unmounted them and shook them everything inside was in bits...

Best of luck and let us know!

tshammas · Post by **tshammas** » Mon Sep 24, 2018 7:45 pm

Thanks for the reply! I will definitely do that

ph001 · Post by **ph001** » Tue Sep 25, 2018 10:22 am

Also happens if you have / had unburned fuel going into the cats which is common after a dodgy coil pack. Had any coil pack issues of late?

ga41 · Post by **ga41** » Tue Sep 25, 2018 10:29 am

I've also had a faulty coil pack at some point but I don't remember if it was around the same time as the O2 sensor/converter problems. I don't think so

tshammas · Post by **tshammas** » Wed Sep 26, 2018 8:23 pm

Car has had a misfire in cylinder no. 5 and there is one of the o2 sensors that need to be replaced.
Now sine I bought the car a few months back I saw that the cats were removed and a straight pipe was fitted. Do I need to have the sensors In since there is no cat? I saw afe have a direct fit cat replacement option and another steel racing pipe and I'm not really sure what is best to do. Keep my existing g setup and replace the sensor or install one of the afe without any sensors??? Any advice please?

https://afepower.com/afe-power-47-46303 ... eplacement

https://afepower.com/afe-power-48-36320 ... -race-pipe

Coil packs and tips already on order just to be on safe side.

Cheers for any advice

tshammas · Post by **tshammas** » Wed Sep 26, 2018 8:28 pm

Sorry I meant TPS on order!

I also am attaching pics of my exhaust system. The car also came with eisemann rear mufflers

ga41 · Post by **ga41** » Wed Sep 26, 2018 9:11 pm

If you were running without catalytic converters then that might very well be contributing to why you smell unburnt fuel... and also if you ran without them and had no check-engine light on then i presume that your car must have a remap which codes the error out.

The sensors need to be able to read a value before and after the converters, if the value is the same (as in your setup without the catalytic converters) then they trigger the check-engine light. There are o2 sensor relocation kits which apparently retain the o2 sensors, don't trigger the fault code and don't need a remap but you need to research a bit because i dont have any personal experience with that and so i've not read up on it..

Hope this helps.

ga41 · Post by **ga41** » Wed Sep 26, 2018 9:15 pm

I guess i have my facts wrong, the relocation kits is for US Z4Ms which have an extra set of catalytic converters on the exhaust manifolds. If they replace them with the ones from the European Z4M's or with aftermarket ones then they need the relocation kit in order not to trigger a fault code. It's not for cat delete pipes....

tshammas · Post by **tshammas** » Thu Sep 27, 2018 7:27 pm

Thanks for the feedback.

I ordered the O2 sensors as the dealor doesn't have parts here. So I will see what happens once I replace it as this issue has happened recently.

I hope this issue gets resolved and I actually get to be able to enjoy the car again!

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