Need e-test advice E36 318i

[topnotchraly]

My 97 318i with 250k kms failed the etest. I half expected this because it barely passed two years ago. I was a bit foolish in that I took it for the test without doing anything. I did replace the air filter before the test.

I have since replaced the spark plugs with new Bosch OEM ones, the old one were pretty shot, though the car ran fine, had been in for 75k kms.

The cat. was replaced 5 years ago, nothing else has been changed. The Check Engine light comes on every 2-3 months saying the cat is failing but I just reset it and it each time.

Anything else I should do before trying the test again? (as I said, I have changed the plugs)

Change the oil?

What gas is best to use? (I normally use 91-93 octane)

Thanks,
James

[archrival]

What did it fail on? Idle or driving and on what gasses and by how much? Also what kind of cat was put on when it was replaced last?

[e30_kid89]

You should be fine with a OE cat or decent replacement. Try a oil change, and o2 sensor. Drive on the highway to the test center in like 4th to keep the rpm's high and the cats hot so when you roll right into the test center its hot and can do its job even more effectively.

[topnotchraly]

Originally Posted by archrival

What did it fail on? Idle or driving and on what gasses and by how much? Also what kind of cat was put on when it was replaced last?

Good point, I should have mentioned that. It passed the idle test fine. It failed all three gases on the load test.

150% over on the HC
12% over on CO
100% over on NO

To answer the other question about the cat. Don't know but the whole cat pipe was replaced from the down pipe to the rear exhaust pipe (it's one piece) I assume it was an OEM quality part.

Thanks,
James

[topnotchraly]

I also just noticed that the 'dilution' on the load test is 15.1, but it's 14.2 on the idle. Does that mean it's lean?

[bmdbley'sBro]

02 sensors arent that expensive.... and if is never been done at 250K its time.

electric contact cleaner the maf sensor & clean your throttlebody flap.

[rwdbmwm3]

yeah id say O2 sensors... if you want 100% answer, get your car scanned by someone who knows what they are doing (im not talking about the garbage scanners but an actual couple grand scanner)

[Mickey Knox]

check for vacuum leaks too

[BalloonWhite]

PVC valves are also a big part of why cars fail e-missions test

[archrival]

ok so judging by what you have i would say an O2 would be a good thing to replace. toss a bit of methyl hydrate in the tank as well. as stated above make sure the car is good and hot to make sure the cat is working to its fullest when you bring it in to get tested. too bad your not OBD1 mustang O2 sensors work if you swap the plug over..if you have a friend who works at a shop see if they can get you a deal on a sensor

[jeffrie]

O2 sensor most likly. Replaced mine recently since it was done and I have 220K on my car, BMW suggests replacment every 160K wither it's within spec or not, since it will increased fuel milage and reduce emmisions.

PVC valves fail @ about the same time and pretty cheap & easy to replace.

[topnotchraly]

Thanks for everyone's input. What I've found is that with results as bad as mine it's likely the CAT has failed. However, I'm going to change the O2 in front of the cat, put in some 94 octane and a can of 'guarenteed to pass'. I've already changed the plugs and air filter.

I'll try this and see what happens...if it failed I guess it's a new CAT then (yike$).

I didn't know BMWs had PCV values...none of my GTIs did...where is it?

Thanks,
James

[jeffrie]

Originally Posted by topnotchraly

I didn't know BMWs had PCV values...none of my GTIs did...where is it?

Thanks,
James

Follow the hose from the back of the vavle cover, it goes streight to the PVC valve.

[topnotchraly]

For the record, I did what I said above. Changed plugs and O2 in front of the cat, put in a can of 'guarenteed' and I passed with flying colours. Offending number went from 1100 ppm to 32 ppm.

[5style]

ohhh well looks like my 02 needs to be replaced, thats probably why my milage is slowly decreasing.