e30 m50 didn't pass smog

[z3ds]

Hi I searched about it and I didn't get the info I need.
(Not alot of m50's that failed smog)

I just bought a 1986 325e m50, the po did a really good job with the swap. I have to smog it here in milwaukee. It failed. The tests says

HC 3.00 and the limit was 2.00
CO 61.3394 and the limit is 30.00

The car runs great. Does the results means I need to change the catalytic? charcoal canister? or is it something little that I need to do..

I never failed a smog test before with other cars so I have no clue. Thanks

[WillisE30]

Not passing by such a small amount is a tough thing to point a finger at. Had you failed HC or CO grossly the problem would be much easier to diagnose via the internet. I would guess that your vehicle may not have been warm enough to light off the catalyst, or possibly that your cat(s) is/are dead. Your coolant temp sensor might possibly be going out which would cause the car to run too rich or lean, but usually when that is the case the failure is more obvious. I'll do some thinking about this and ask some of my more experienced friends. I'm a state certified specialist here in WA, but really all that means is that I have a good idea what is going on and was able to pass a test. Hopefully I can help.

[browntown]

i know nothing about emission tests, but if you're off a little I'd think an ignition tuneup wouldn't hurt, and if you're running rich, your plugs will be fouled. also internet forums love to blame the 02 sensor for everything and anything, but that can be a costly fix depending how handy or inept you are with splicing wires for a universal or buying one with the premade pigtail.

then you can go with the maybe it works maybe it doesnt, and pour in some seafoam. I'm not ready to jump on that bandwagon, but the two additives I've used for years in every car I own is lucas fuel injector cleaner (dont use stp or alike, they're all alcohol), and "restore"

if the m50 is chipped, and you can swap chips without soldering, I'd put the stock chip in.

just brainstorming here, good luck

[z3ds]

Thanks WilllisE30 and browntown for the prompt reply

I would guess that your vehicle may not have been warm enough to light off the catalyst, or possibly that your cat(s) is/are dead. Your coolant temp sensor might possibly be going out which would cause the car to run too rich or lean, but usually when that is the case the failure is more obvious.

I can x the possibilty of the cat not being warm enough as I drove the car for more than 30min (i hope thats enough). However I noticed that the temp meter was on the low side (the needle was just pass the blue bar) even if I was driving for more than an hour. I dont know if thats normal or if the needle supposed to be in the middle?

The car has an obdII exhaust manifolds and i think the o2 sensors were repositioned. might be the cause?

I believe the car is not chipped the po didn't mention about it but I will check the ecu.

I will also check the spark plugs if they are fouled.

Will update..

[LINUS]

The car has an obdII exhaust manifolds and i think the o2 sensors were repositioned. might be the cause?



Will update..

Not likely the manifolds. OBD2 has a port on each mani, and I bet you either have a bolt/plug in each one, and the O2 sensor is still where it belongs in (hopefully) your M50 e36 center section, right at the joint of each downpipe.

There might be OBD2 O2 sensors hanging out of the manifolds - look at the rearward side of the common for a ~15 mm bolt or a strange thing with a small pigtail with 3-4 wires. then look further down the pipe to see the O2 sensor that should be there - and plugged in.

I vote check on the chip, then O2 sensor health/connection. If you unplug a good O2 sensor, the engine should slightly lug and run richer - plug it back in and it should smooth out and probably run leaner.

If you can figure out how many miles are on the O2 sensor in question, that would be good posting information.

[z3ds]

Spark plugs looks clean and good
Also acquiring the info about the o2

btw the car is obdI

will update..

[WillisE30]

[quote=z3ds;645243]
I can x the possibilty of the cat not being warm enough as I drove the car for more than 30min (i hope thats enough). However I noticed that the temp meter was on the low side (the needle was just pass the blue bar) even if I was driving for more than an hour. I dont know if thats normal or if the needle supposed to be in the middle?
quote]
Ideally your car should be at full opperating temp, somewhere in the middle of the gauge, well assuming your gauge is working correctly. I've seen MANY cars fail simply because they weren't warm enough. On your retest beat on the car good and hard before you go get it smogged.

As for the coolant temp thing, is your car warming up properly? Do you have good heat? Is your thermostat sticking open? These are all considerations.

The reason I tend to not suspect ignition parts is that with ignition related failures you tend to see extremely high hydrocarbons, usually the vehicle will misfire and all the unburnt fuel will register as HC. Doing a full tune up certainly won't hurt though.

I would also look to the chip as others suggested as it might be part of the problem.

[z3ds]

Ideally your car should be at full opperating temp, somewhere in the middle of the gauge, well assuming your gauge is working correctly. I've seen MANY cars fail simply because they weren't warm enough. On your retest beat on the car good and hard before you go get it smogged.

I would also look to the chip as others suggested as it might be part of the problem.

Just talked to the po and he told me that he used a euro 80 deg thermostant:p i guess problem solved!? He also mentioned that the car isn't chiped.

I'll put a 88 deg thermostat as the po adviced me and will do a retest.

I also used some seafoam to the gas to help as well.

will update..,

[PiercedE30]

I blame the O2 sensor.............

[LINUS]

I still vote O2 sensor. I know my Landcruiser (OBD2) has brain logic where if the O2 sensor isn't reading within set values, it goes into 'limp home' mode that means rich A/F ratio. I bet that same logic carries over to the 413 brainbox.

Simple test is still to unplug the O2 sensor like I described above. Or cut loose the $80 and start with a known condition O2 sensor.

Make sure you post when you find your culprit. I hate searching threads where nobody follows up with a solution.

[z3ds]

I still vote O2 sensor. I know my Landcruiser (OBD2) has brain logic where if the O2 sensor isn't reading within set values, it goes into 'limp home' mode that means rich A/F ratio. I bet that same logic carries over to the 413 brainbox.

Simple test is still to unplug the O2 sensor like I described above. Or cut loose the $80 and start with a known condition O2 sensor.

Make sure you post when you find your culprit. I hate searching threads where nobody follows up with a solution.

The previous owner mentioned that he doesn't know how old the 02. I forgot to do the test yesterday. I did it today, and when i unpluggged the o2 sensor nothing happened. I assume that the o2 sensor in my car is from a 525i (were my m50 came from)

[DREWHALL]

So if it didn't do anything when you unplugged it, it means it's a bad sensor? Or somethings not working right? I wouldn't mind knowing for future reference.

[1990m3]

if you want to come see my car you can to compare parts. I have all emissions equipment in place and have passed emissions. I live downtown and work in Brown Deer. i know which car you bought. I wiring is all done correctly, that car will pass if the correct parts are there. You should test the O2 sensor according to the bentley manual's voltage reading criteria, not just the plug in plug out method.

[MikeE30325i]

Thanks WilllisE30 and browntown for the prompt reply




I can x the possibilty of the cat not being warm enough as I drove the car for more than 30min (i hope thats enough). However I noticed that the temp meter was on the low side (the needle was just pass the blue bar) even if I was driving for more than an hour. I dont know if thats normal or if the needle supposed to be in the middle?

The car has an obdII exhaust manifolds and i think the o2 sensors were repositioned. might be the cause?

I believe the car is not chipped the po didn't mention about it but I will check the ecu.

I will also check the spark plugs if they are fouled.

Will update..

that is pretty cold for the engine temp. it should be a little in front of the halfway mark. that might have something to do with it.

[Erick]

If your car is running past the 1/2 way mark, you have cooling issues.