MyE28.com

Jeremy wrote:You're running way too rich to pass with those CO numbers.

Can't you get an exemption after spending that kind of $$$s?

Jeremy

Yeah, I know I'm running wayyyyyyy rich but I'm out of ideas man. Nah, in this Godforsaken state you can only get an exemption if I fail NOX, which I'm passing with flying colors.

I know it is frustrating, but it sounds to me like the car has never been diagnosed. Do you have a good BMW shop in your area that can look at the car? I would suspect at this point that you have leaky injector(s), a leaky cold start injector, or maybe something else we are missing.

Are you getting carbon under the rear bumper? Some is normal, but it shouldn't look like a coal mine back there. I really suspect you have bad injectors. But it is time to stop throwing parts at the car and get a pro involved -- someone who knows the M30 beast well, and you will only find them at a BMW shop.

I will say this, if those injectors are original at 300k miles, I am sure they are well past the point of being sloppy and leaking.[/quote]

I feel ya man. I bit the bullet and took the car to arguably the best BMW mechanic in NJ. He ONLY works on BMW's and knows crazy amounts of knowledge about these cars. He adjusted my valves, did a whole bunch of little shit (including adjusting the AFM) and thought I was going to pass. Now I blew $700 and I'm back to square 1. Is there any way to test the injectors? The PO was pretty good with serviceing the car up until about 95 and I see no receipts for injectors so I think they probably are original. Do you really believe they could be burning that much fuel though?

Mike W. wrote:I know you're about ready to scream now, and have thrown a bunch of money and parts at it, but have you done any troubleshooting? Or have you just changed parts?

#1, absolutely, is the O2 sensor output. What does it say? I have a hard time believing you are seeing 4% CO with a new cat and the O2 is showing things working as they should. I know you replaced it, I didn't say that, I said what is the output when running? That is the key to the whole thing.

I didn't test the output Mike, I am really good with mechanics but anything electrical is foreign to me and I suck at it. Do I just hook up a voltmeter to the O2 sensor lol. God I'm terrible at electronics.

e34 530 wrote:

Mike W. wrote:I know you're about ready to scream now, and have thrown a bunch of money and parts at it, but have you done any troubleshooting? Or have you just changed parts?

#1, absolutely, is the O2 sensor output. What does it say? I have a hard time believing you are seeing 4% CO with a new cat and the O2 is showing things working as they should. I know you replaced it, I didn't say that, I said what is the output when running? That is the key to the whole thing.

I didn't test the output Mike, I am really good with mechanics but anything electrical is foreign to me and I suck at it. Do I just hook up a voltmeter to the O2 sensor lol. God I'm terrible at electronics.

Yeah, that's it. Even a cheap digital will work just fine. Hook it up, set it on the 2 volt DC scale and see what the output is. Leave it connected to the system, use some aligator clips or aligator clip leads to hook it up. You can get a pack of them at Radio shack for about 3 bucks. Hook one side of the meter to ground (I usually use one of the strut mounting studs that are sticking up), the other side to the O2 sensor lead. When it's working right, it will be bouncing up and down, from .2 volts to .8 volts. Or even more. It should seem like it's averaging about half a volt, or .5 Technically it's .45, but I'm pretty good with math in my head and it moving from .2 to .6 to .5 to .8 to .8 to .1 to .5 all in a couple of seconds is more than I can calculate. I suspect you will see something steady, at .6 or above. A high number is rich, a low number is lean, your tests suggest rich. See what you get and we'll go from there.

Two things I can add:

First, Mike is right (as is usually the case), but it raises the possibility in my mind that the shop that you are using may not be doing right by you. A good BMW shop, hell any good shop, would want to test the O2 sensor.

Second, if it is not the O2 sensor, then I would pull all the injectors. That's just my guess. To know more, I would want to listen to the car run and drive it to get a better sense.

Hth, and good luck.

Mike is dead on with testing the O2 sensor. While a narrow band O2 sensor is not reliable for tuning in a turbo or high performance application, it's perfect for tuning to meet emissions. The reason is primarily the very narrow range of output voltage it's capable of generating, 0- 1 vdc. Since stochiometric A/F ratio of 14.7:1 occurs at about .47 - .55 vdc or Alpha =1, and the 3 way catalytic convertors require the A/F ratio to vary very slightly between slightly rich and lean of Alpha =1. The narrow band O2 sensor is the perfect tool to use in combination with a digital multimeter to determine how your engine is performing in regards to emissions.

When I bought my current 535i/A the PO's shop had adjusted the AFM to lean the A/F ratio and compensate for the 5000 ft elevation in which he resided. I live in Spring, Texas which is 155' above sea level, therefore the AFM adjustment was far too lean. So I had to readjust the AFM to correct the lean A/F ratio, but to also pass the very tough ASTM-II SMOG test we have in Harris County (Houston metro area). The O2 sensor in combination with my Fluke meter is all I used to do this. Once adjusted I have passed the ASTM-II SMOG test 3 times without any issues.

Rich