1994 530iT Nikasil Failed CA Smog Again

[djankov]

I just got back from the 2nd failed smog in 2 weeks. After the first test, mechanic said I needed 2 new Cats at a cost of about $800 plus installation. I decided to try the following before buying the new Cats:

1) Replaced Oil, Mobil 1 5W30 - Walmart
2) Replaced Spark Plugs – Bosch Platinum (8) - Walmart
3) Replaced Valve Cover Gaskets (All 4) - Dealer
4) Did Compressions Test (1-151, 2-150, 3-150, 4-149, 5-152, 6-150, 7-151, 8-156)
5) Replaced O2 sensors (2) - Online

I passed all but the HC at 15 MPH.

--------------RPM---%CO2--%O2--------HC (PPM)----------CO (%)------------NO (PPM)
--------------MEAS--MEAS--MEAS--MAX--AVE--MEAS--MAX--AVE--MEAS--MAX--AVE--MEAS--RESULTS
M1: 15 MPH---2125---14.6---0.3----81----21---125---0.47---0.06---0.22---683---150---560---FAIL
M2: 25 MPH---2095---14.8---0.0----46----13----39---0.44---0.05---0.06---692---136---254---PASS

The engine has no trouble starting and runs smooth at idle.

What should I do? Will a leakdown test give me any additional information? I will go ahead and get the Cats if I need to, however, I would hate to buy them and burn through them because of other problems. How long do Cats last anyway? I had an ’88 M3 which never needed a new Cat and it had 192,000mi when I sold it.

1994 530iT 126 kMi
2004 CLK 500 Cabrio 18 kMi
1987 300TD 209 kMi
1987 300D 189 kMi

[Gayle]

Did you get the cat heated up before the test and get them to test it while it was hot?

[Tiger]

Do you have performance chip installed? This chip will alter the fuel ratio... If cat was bad, it would fail at 25 MPH too... so your cat is fine.

Your compression is a bit low for this type of engine... I would try the guaranteed to pass emission fuel additive to get by.

[632 Regal]

I would recommend that you use the standard Bosch F7LDCR or NGK BKR6EK, There has been known issues with any of the performance plugs.

The cats have to be HOT HOT HOT for it to pass because they are a lot farther from the engine than other cars, If it sits for ANY time it will FAIL.

[Tiger]

Ahh! I missed that... good call!

[632 Regal]

2 heads are better than one

Ahh! I missed that... good call!

[djankov]

I was told they worked on getting the Cats hot. I wasn't there, so I was unable to verify. There is no performance chip that I am aware of. How can I tell? Also, the car accelerates smoothly, but shifts early enough so it does not rev the engine much in D. In 4S, it performs better, but still not that great. Should I go to another smog station? Can I rule out Cat replacement?

1994 530iT 126 kMi
2004 CLK 500 Cabrio 18 kMi
1987 300TD 209 kMi
1987 300D 189 kMi

[632 Regal]

you HAVE to make sure the cats are HOT, I think that this is the whole problem, it will NEVER pass if they arent hot, even with brand new ones.

[SharkmanBMW]

I was told they worked on getting the Cats hot. I wasn't there, so I was unable to verify. There is no performance chip that I am aware of. How can I tell? Also, the car accelerates smoothly, but shifts early enough so it does not rev the engine much in D. In 4S, it performs better, but still not that great. Should I go to another smog station? Can I rule out Cat replacement?

1994 530iT 126 kMi
2004 CLK 500 Cabrio 18 kMi
1987 300TD 209 kMi
1987 300D 189 kMi

please post pics of your CLK.... nice ride!