e36 320i 1997 no post-cat o2 sensors

[Ture]

Hi,
I recently bought an e36 that do not pass the emissons test. (with a completely new exhaust) so i started locking around checking sensors and i found the two pre-cat o2 sensors in the two exhaust manifolds, but no post-cat o2 sensors and the exhaust doesnt even have the holes for them.

Any help would be much appreciated.

p.s English is not my first language

[328 Power 04]

Some of the Euro versions came like that, so it depends on the equipment. No errors in the engine computer?

If it failed emissions because it failed the tailpipe sniffer, make sure you do a hard spirited drive to get the cats very very hot right before, and potentially run a bit of ethanol blend fuel (E10-E15 max). If you do tailpipe sniffer on a cold engine, it will fail.

What parameter failed specifically?

[bmwdirtracer]

Welcome to the forum!

Your English is much better than many people who call it their first language.

I agree fully with Abel; the engine and catalyst need to be fully hot immediately before the testing. AND, if you'll give us the specific results, we can advise better. I know it's very difficult for a new member to post attachments, but if you can post to a hosting site, and give us a link, we will have a look.

I'd also advise having a fresh set of stock spark plugs in for your testing. I prefer NGK. You should make sure there are no intake system leaks (a professional smoke test is best), and all the basic sensors (intake air temp, coolant temp, mass airflow, and the O2 sensors) are reading numbers that correlate to reality.

[Ture]

Ty for the reply,
Before the inspection i filled it up with like 20-30% etanol and took a 20 min drive and it has new spark plugs to.

The results i got where, CO 2500 RPM: 5,7 (0,3), CO: 5,1 (0,5), O2:0,84 (0,97-1,03) and HC:434 (200) where the first numer is what i got and the second in () what it should have been.

[328 Power 04]

Ty for the reply,
Before the inspection i filled it up with like 20-30% etanol and took a 20 min drive and it has new spark plugs to.

The results i got where, CO 2500 RPM: 5,7 (0,3), CO: 5,1 (0,5), O2:0,84 (0,97-1,03) and HC:434 (200) where the first numer is what i got and the second in () what it should have been.

I'm going to guess this is lambda value from the O2 sensor. This is running a bit rich (more than necessary fuel) and then the carbon monoxide and the hydrocarbon readings will be much higher, if true.

Any modifications to the car of any kind? Any codes in the engine control module (DME)?

[Ture]

yes its the lambda value,
The only modifications i know of and the prevues owner told me about is the new exhaust.

I do not have a code reader at home so i havnt checked but I know someone who I can borrow one from.

[328 Power 04]

Also, if the coolant temperature does not reach operating temperatures (like a stuck open thermostat), or it's simply a cold engine, then the engine ecu will add a lot more fuel in order to help warm up the catalytic converter as part of catalyst heating routines.

[bmwdirtracer]

OR, if the coolant temperature sensor is telling the DME that the engine is stone cold, the DME will similarly feed way too much fuel. This could be as inexpensive a fix as replacing the ECT sensor...or even making sure it's plugged in! If your friend has a good scan tool, you should be able to see live data for the ECT sensor, and intake air temp.

Car is running rich, incomplete combustion. Check such things as a clogged air filter, wrong fuel pressure regulator, etc.

[Breeze1]

I'd make sure that the cats are the stock ones (not high flow cats), and that they haven't been hollowed out. While not seemingly related, if your MAF sensor is off or if there is a vacuum leak, it could cause a rich mixture, if the DME is compensating the excess oxygen by dumping more fuel. You can scan the car for faults related to this.