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RE: Mass State Inspection Emissions on e34 530i

schneller — Wed, 11 Jun 2008 09:05:56 GMT

So you're failing on 2 counts:

HC which means that the car is running too rich.

and

NOx which indicates that CAT efficiency isn't what it should be.

V8s have been known to wear out CATs. The reason for this is that the crankcase oil separator systems allow oil back into the intake where it is then introduced into the cylinders for combustion. Oil has low octane, so if there's enough of it you'll see some misfire codes. When the problem is in its infancy, the volume of oil is low enough that misfires don't show, but it makes the exhaust gases rich, which the O2 sensors try to trim back but can't. In the end the CATs wear themselves out catalyzing this extra fuel (that isn't at all metered). So you end up w/ higher HC readings and a compromised CAT (High NOx).

I would begin with removing the intake manifold, replacing all of the orange colored intake, throttle body & rear cover gaskets. Replace the rear manifold cover as it is the part of the crankcase ventilation system that allows oil into the intake when it fails. Also, check out the intake, if it's quite oily, then there's your problem. Be sure to clean it out. Since you're in that deep you might consider it a good time to do the water pump, T-Stat, cooling tube O-Rings & valley pan gasket.

If this isn't your problem, I'd have the engine leak down tested. Not enough compression will incompletely burn fuel, allow oil into the combustion chamber past the rings & will begin at its early stages to produce those types of emissions readings.

Finally, since NOx is now being evaluated, we're seeing many after market CATs fail emissions tests (even new out of the box). Previously, these CATs didn't actually need to work as no one was checking NOx. Inspectors were just peaking under the car to see if a CAT was indeed there. After market V8 CATs have been known to not pass emissions tests. If your car is sporting these, you may also need to pony up the $ for factory converters.

Good Luck!;)

RE: Mass State Inspection Emissions on e34 530i

BlueE34 — Tue, 10 Jun 2008 20:36:26 GMT

Sure Mike,

In 2000 at 80K miles:

and 11/2007 at 160k:

and... in 1/2008 trying a bunch of dry gas at about a 4:1 ratio of Gasoline to Methanol in the tank:

...Maybe 2:1 would have worked...

I didn't own it during the 2000 test, so I'm not sure what was going on there. The cats now have maybe 55K on them and are almost 3 years old, but the car never passed on its own merit, even right after. I've always run it as hot as possible, usually about 1 hour of highway before testing, and I've gotten mixed results going to different places, it seems there are a fair amount of variables during the test. Thanks again,

Patrick

RE: Mass State Inspection Emissions on e34 530i

schneller — Mon, 09 Jun 2008 17:53:42 GMT

Can you provide the exhaust gas analysis? Actual values & limits?

Thanks,

Mass State Inspection Emissions on e34 530i

BlueE34 — Mon, 09 Jun 2008 13:29:23 GMT

Hello Mike,

I just posted this in the car section, I've always heard great things about you and your shop, so I figured I'd give it a try here as well.

My current '94 530i (160K) keeps failing on emissions even though I've replaced many parts and I have kept up with maintenance.

I am fully aware of the Nikasil problem and my engine doesn't seem to have this issue, I've had it compression and leak tested.

Cats have been replaced, complete intake reseal, all tune up items done always, not sure on smog pump status, and I've reset the adaptation values, all to only improve but not pass emissions testing. Idles well (for a V8 of its generation), and doesn't smell out the pipe, or blow smoke, and MPG is/are ok, no engine hesitation IMO, no OBD II-only dyno.

One thing is that when my car is tested for some reason the engine status comes up as a 6 cylinder on the state inspection page. And also the emission results are very similar to what it was producing in year 2000 (i have paperwork, back then it came up as an 8cyl.) and by the standards of 2000 it still passes, but in 2008 some of the limits have been cut to 1/3 of 2000.

Personally I think the limits have become too stringent and the car is just fine. Any help at all would be greatly appreciated. Thanks Mike,

Patrick