1994 318i failed emissions test. please help

[netdude]

It's that time of the year again... the dreaded smog test.

The last time I tested was a couple years ago and I barely passed. I have a 1994 318i all stock.

I went to the smog guys a couple of times this week (utilizing the free retest). No go. Here are my numbers:

1st test (drove 20 miles on freeway before taking test):
/////////// 15mph // 25mph
RPM ////// 1716 // 1698
CO (mea) 15.1 // 14.9
O2 (mea) 0.1 // 0.2
HC (max) 61 // 35
HC (mea) 26 // 19
CO (max) 0.34 // 0.47
CO (mea) 0.15 // 0.21
NO (max) 486 // 502
NO (mea) 626 // 658

2nd test (drove 7 miles on surface road at 45mph max before test, idle 5 mins):
/////////// 15mph // 25mph
RPM////// 1929 // 1781
CO (mea) 14.8 // 14.4
O2 (mea) 0.0 // 0.0
HC (max) 61 // 35
HC (mea) 3 // 1
CO (max) 0.34 // 0.47
CO (mea) 0.01 // 0.01
NO (max) 486 // 502
NO (mea) 909 // 617

I was so close on the 1st one, I thought, after filling it with new gas (always premium), I should pass. I thought way wrong. When I drove there, the car was fine. Then after idling for 5 mins and the guy drove it up to the dyno, the idle started acting a little funny and revved up and down for a sec. It's happened before, but always randomly (like this time). I've read cleaning the ICV may help this problem.

I've read up for the past couple hours on what high NO means and it seems like I"m stuck possibly looking at a new CAT. I've read differing opinions about the O2 sensor. I haven't changed my spark plugs in about 4 years (though only driven <15k miles in 4 years).

Before taking the 1st test, I did do:
1. change oil (Mobil 1 5/30)
2. clean the throttle body w/ toothbrush and TB cleaner
3. 1 bottle of Lucas fuel injector cleaner

Any thoughts on what I should do to attempt to pass smog? From what I've read on tonight, cheap things might be to change the O2 sensor (Ford goes for $35 or so) and spark plugs at $4/each or something. I'll definitely clean out the ICV this weekend. I saw the DIY and it's hopefully doable.

Some folks have mentioned checking the EGR valve. I'm not sure where it is and not sure how difficult it may be to replace or even it exists for the 1994 318.

Also, I recently got the CEL and pulled the code: 1222.  The CEL only comes up when I'm stopped at a light for a while.  From reading up, it's almost anything intake related. I thought it may have been a vacuum leak so did the throttle body cleaner test and sprayed a bunch of TB cleaner around the intake while the car was on idle.  The idle never changed so I'm led to believe that it's not a vacuum leak.  Maybe O2 sensor?

Thanks in advance for any insights into this problem and helping me get through the dreaded smog test this year.

Cheers

[DesktopDave]

Welcome to the board...let's see what we can do to help.  I'll share my philosophy with you.  Do the cheapest/easiest stuff first, especially if it's a long-term fix or helps with durability.

You read the codes, great first step.  A 1222 is an O2 sensor, IIRC.  Could be a vac leak too, but I'd suspect the sensor first.    I'd also change the O2 sensor with the Ford Bosch (all V8 modular  engines IIRC) equivalent.  High NOx is usually due to a lean condition.   The O2 sensor potentially the cheapest fix.

I'd absolutely change the plugs.  I swap mine every few years.  I'd recommend the plain old NGK copper plugs, or the Iridiums if you don't mind the cost & want long-lasting ones.

I'd also test the engine & air intake temp sensors.  It's a quick & easy test.  If the car doesn't heat up properly you'll never pass an emissions test and it's really hard on the engine.

I'd be very tempted to pull the intake manifold and replace all the hoses, or consider the hose delete mod.  It's a PITA, but it likely has to be done anyway.  You might have some troubles with the visual emissions inspection in your locality.

The other mod that might help a lot is the upgrade to Bosch yellow 19# injectors with new O-rings.  If you have a rough idle that's a good way to clear it all up.  It is a very involved process though, I'd only do it if I was really obsessed with keeping the car.

[netdude]

Thanks for the reply. I've got a new O2 sensor and NGK 2288 plugs in hand.  I'll have those replaced this weekend after running seafoam through the system.

I'm starting to suspect my engine temp sensor.  It's been cold in the San Francisco bay area these past couple of days and I can't seem to get the car to temp.  Then again, I'm only driving it 5 miles each eay.  The temp stays at 0 for like 3 miles, then when I jump into the freeway, it goes a little over 1/4 the way.  i can't get it near 1/2.  Do you know a quick way to check the temp sensor?

I'll be pulling off the intake manifold this weekend and cleaning out the ICV.  I'll look over the hoses at that time.

Thanks again for your suggestions.  Let me know if you've got other thoughts, especially about the temp sensor.  Thanks!

[DesktopDave]

Cold engines run very rich and ignore the O2 sensor...that's called 'open loop.'  That might be the root of your problems, fixing it can't hurt.  Even if it isn't causing the emissions to fail it's really hard on the engine.   I'd assume that the new O2 and plugs will help, but I'd save my inspection payment until I'd cleared up the temperature problem.

So I'd highly recommend testing the temp sensors.  But (disclaimer! ) I haven't worked on an e36 yet (though the Ti is such a tempting little car), so please double-check this info...

Both the coolant temp and AFM air temp sensors get a resistance test.  The gauge runs off it's own temp sensor (rear plug on the driver's side of cylinder head), so make sure you're testing the right one...the DME sensor has two terminals (and it's closer to the front of the engine), the gauge sensor has one (and it's further back).  According to the BMW repair manual, both the AFM and coolant temp sensors have the same specifications.  A cold sensor's resistance (spec is 58degF) should be about 2500 ohms.  Hot (spec is 180degF) should be 'round 300 ohms.  I'd assume that any temperatures in between can be interpolated.

Could also be a stuck-open thermostat or frozen clutch on the engine fan too. Bleeding the car is a PITA, but it's worthwhile to fix it.  You should get better fuel mileage as a result too.

[netdude]

Cold engines run very rich and ignore the O2 sensor...that's called 'open loop.'  That might be the root of your problems, fixing it can't hurt.  Even if it isn't causing the emissions to fail it's really hard on the engine.   I'd assume that the new O2 and plugs will help, but I'd save my inspection payment until I'd cleared up the temperature problem.

So I'd highly recommend testing the temp sensors.  But (disclaimer! ) I haven't worked on an e36 yet (though the Ti is such a tempting little car), so please double-check this info...

Both the coolant temp and AFM air temp sensors get a resistance test.  The gauge runs off it's own temp sensor (rear plug on the driver's side of cylinder head), so make sure you're testing the right one...the DME sensor has two terminals (and it's closer to the front of the engine), the gauge sensor has one (and it's further back).  According to the BMW repair manual, both the AFM and coolant temp sensors have the same specifications.  A cold sensor's resistance (spec is 58degF) should be about 2500 ohms.  Hot (spec is 180degF) should be 'round 300 ohms.  I'd assume that any temperatures in between can be interpolated.

Could also be a stuck-open thermostat or frozen clutch on the engine fan too. Bleeding the car is a PITA, but it's worthwhile to fix it.  You should get better fuel mileage as a result too.

Thanks.  I'll go find that temp sensor and see if I can check the resistance. The outside temp here is in the 40s so it's a bit cold to be working on the car.  I guess that's what I get for not want to take it into the shop and pay an arm/leg.

I was thinking the thermostat may be stuck open too and didn't know if there was a way to find that out easily without draining the system.  I recall the thermostat is towards the bottom of the engine, right?  I'd have to pull off the lower hose and pull out the thermostat?

The stuck clutch for the ran is an interesting thought.  I thought it was just my car, but now you've got me thing / asking.  So, I haven't seen another E36 318 before.  My fan goes all the time.  I mean, I turn on the car, and the fan is on.  Is that normal?  I know that on my other cars (toyota), they turn on when necessary.  However, my 318's fan is on ALL THE TIME.  Can you tell me if that's the clutch being stuck?  (I didn't know the fan had a clutch!)  

Thanks again!

[DesktopDave]

Some e36 318's have electric fans.  I'm not sure what years or models had that setup.  All the e30's have an electric aux fan and engine-driven clutch fan mounted to the water pump pulley.

Regardless, the fan should not be on all the time.  There is a thermoswitch on the passenger upper side of the radiator that determines if the fan is off, on low speed or on high speed.  A/C will also turn on the electric fan at low speed when it's on. Check out post #7 on this thread for the testing method.

[318isam]

It's that time of the year again... the dreaded smog test.

The last time I tested was a couple years ago and I barely passed. I have a 1994 318i all stock.

I went to the smog guys a couple of times this week (utilizing the free retest#. No go. Here are my numbers:

1st test #drove 20 miles on freeway before taking test):
/////////// 15mph // 25mph
RPM ////// 1716 // 1698
CO (mea# 15.1 // 14.9
O2 #mea# 0.1 // 0.2
HC #max# 61 // 35
HC #mea# 26 // 19
CO #max# 0.34 // 0.47
CO #mea# 0.15 // 0.21
NO #max# 486 // 502
NO #mea# 626 // 658

2nd test #drove 7 miles on surface road at 45mph max before test, idle 5 mins):
/////////// 15mph // 25mph
RPM////// 1929 // 1781
CO (mea# 14.8 // 14.4
O2 #mea# 0.0 // 0.0
HC #max# 61 // 35
HC #mea# 3 // 1
CO #max# 0.34 // 0.47
CO #mea# 0.01 // 0.01
NO #max# 486 // 502
NO #mea# 909 // 617

I was so close on the 1st one, I thought, after filling it with new gas #always premium#, I should pass. I thought way wrong. When I drove there, the car was fine. Then after idling for 5 mins and the guy drove it up to the dyno, the idle started acting a little funny and revved up and down for a sec. It's happened before, but always randomly #like this time#. I've read cleaning the ICV may help this problem.

I've read up for the past couple hours on what high NO means and it seems like I"m stuck possibly looking at a new CAT. I've read differing opinions about the O2 sensor. I haven't changed my spark plugs in about 4 years #though only driven <15k miles in 4 years#.

Before taking the 1st test, I did do:
1. change oil #Mobil 1 5/30#
2. clean the throttle body w/ toothbrush and TB cleaner
3. 1 bottle of Lucas fuel injector cleaner

Any thoughts on what I should do to attempt to pass smog? From what I've read on tonight, cheap things might be to change the O2 sensor #Ford goes for $35 or so) and spark plugs at $4/each or something. I'll definitely clean out the ICV this weekend. I saw the DIY and it's hopefully doable.

Some folks have mentioned checking the EGR valve. I'm not sure where it is and not sure how difficult it may be to replace or even it exists for the 1994 318.

Also, I recently got the CEL and pulled the code: 1222.  The CEL only comes up when I'm stopped at a light for a while.  From reading up, it's almost anything intake related. I thought it may have been a vacuum leak so did the throttle body cleaner test and sprayed a bunch of TB cleaner around the intake while the car was on idle.  The idle never changed so I'm led to believe that it's not a vacuum leak.  Maybe O2 sensor?

Thanks in advance for any insights into this problem and helping me get through the dreaded smog test this year.

Cheers

so i am having the same issues with failing smog with my '95 318I with 246K miles with factory O2 sensor and cat.:mad: Here are my numbers....

http://www.m42club.com/forums/album.php?albumid=194&pictureid=1147

i am guessing my 17 year old O2 sensor has outlived it's life span and causing my lean condition as i too am spitting out VERY high NO's. i am just hoping my cat isn't fried from driving around with a bad O2!:eek: did the O2 swap and spark plug changes fix your issues and did you pass emissions?:confused: