'94 530im Fails Emissions Test

[Super90]

OK, the old 5er just failed the Texas State Emissions Test. Car has 140k mi. on it, and has been very carefully maintained according to prescribed schedules. No codes thrown in a while and the most recent one was for an O2 sensor, so I put in two new ones from BMA about a year ago.

Here is the data from the test:

HC (PPM) 228 max allowed 112 FAIL
CO (%) 0.49 max allowed 0.62 PASS
CO2 (%) 14.5
O2 (%) 0.6
Nox (ppm) 1156 max allowed 829 FAIL
Dilution 14.99 need >6 PASS



Question is, what to do next? Seems like I am way out of range on Hydrocarbons, so is trying another testing facility worth the $40 ? Is there any way to do some troubleshooting on my own ? Car doesn't have OBDII, so there were no other data available. Or, do I just need to go to the local indy and have them diagnose ?

TIA

[yaofeng]

Bad cats will cause the HC to be out of wack, sometimes NOx also. Are the cats original? If it turns to be the cats it could be expensive.

[Super90]

Yes, I am afraid it could be the cats, and yes they are very expensive. Last time I priced them they were about $1200 ea, IIRC. That is the very, very last thing I would be willing to replace. All other rocks will turned over first.

I just put some Redline Fuel System Cleaner in the car just now and will run it hard for a few days. It doesn't get a good workout in my normal commute to the office and back, so maybe there is some carbon build up going on. Also, if I understand the M60 motor, there is no EGR system, and the car relies on the cats to do a good bit of the work. I have a feeling the car sat too long before the test was performed and they were not really at proper temp. so getting them good and hot before the test could help a bit. I always run premium gas in it but we are in an area with up to 10% ethanol. Would that help or hurt?

Ideas ?

Thanks again.

[Paul in NZ]

and it will make some difference is oil is fresh,car(and cats) are hot....run some injector cleaner through too,just before you change the oil.

[Super90]

Yep, they were OE cats from BMA, but that was about four years ago when I priced them. Aftermarket cats for M60 cars were a bit dodgy back then and no one really recommended them.

[Super90]

We'll do. Thanks !

[AngryPopTart]

Is that $1200 for factory replacements? On my 525i I just use an aftermarket replacement and it passed just fine, and it was alot cheaper than the factory replacement cat.

[Super90]

That's the plan. Try the easy, cheap, obvious things first, then go try the test again within my 15 day period. If we fail again, we are going to the indy for a full diagnosis.

Funny thing is, the car has new O2 sensors, recent plugs and intake seals (13k mi.), I run only premium gas from known sources, only Mobil 1, change the filters frequently, she runs strong and idles smooth. And this is an original block M60.

I am just wondering if she needed a fuel system cleaning and that the cats were not at good operating temp. It sat for maybe 30 minutes before they did the test, it was about 65 degrees outside, and I wasn't driving her very hard before we showed up.

Keep the ideas coming ! Thanks fellas !

[mikell]

If it's cats, go with magnaflow replacements - way cheaper and still very good.
My 530i failed TX emissions, too and there are all kinds of other reasons why it can happen with an older car. In my case, some solder joints on the DME had cracked, which gave erratic and intermittent control to the spark - I can't take credit for finding this out, but re-soldering things made it right.
The o2 sensors could still be bad, or you could have one or more corroded wiring connectors - often ground wires. Or a spark coil (or 2) could have gone a bit south, so giving weak spark.
I took mine to an indy shop here (Houston) where they have the equipment and know how to deal with this complex stuff - never the dealer.
Good luck.

[Lordsneldon]

Yep, they were OE cats from BMA, but that was about four years ago when I priced them. Aftermarket cats for M60 cars were a bit dodgy back then and no one really recommended them.

I wouldnt bother going to the stupid expense of changing the cats when it is most likelly the lambda sensor which sits in the cats. Give that a go first it'll probably cost you less than £100 ($198)

[bubba966]

You need to have the cats good and hot for it to pass. And it sounds like they weren't much past warm.

Finish running your fuel system cleaner through it. Then take it back again any make sure you've got it up to temp by running it hard just before you take it in for the test.

If it still fails after that (and I doubt it will) then you've probably got bad cats.

But it really just sounds like your cats were cold, and they need to be hot.

Would run the test on Chevron Super, without the ethanol if you can get it.

Oh, and when I did a WA state emissions test last year on my M-Sport at about 153K miles my emissions were insanely lower than that (might have to pull the test out and post the results for you). Ran Chevron Super in it, and got the cats good and hot beforehand. I actually surprised the testing guy with the results as the emissions were so low.

[Super90]

Thanks for the note.

I like the plan. Funny thing is, I have only driven the car about 6 or 7k miles since the last inspection (11/06, oooppps) . Last time it passed no problem and I have added the new oxygen sensors, new fuel filters, cleaned the intake valve and ICV, and run now the second bottle of Redline Fuel System Cleaner in the car. It should be better than last time !!!

Appreciate it,

R.

[Super90]

Aren't lambda sensors the same as oxygen sensors (aka "O2 sensors") ?

If so, that was done about 6k miles ago.

Many thanks,

R.

[bubba966]

Aren't lambda sensors the same as oxygen sensors (aka "O2 sensors") ?

If so, that was done about 6k miles ago.

Many thanks,

R.

Yes, they're the same thing.

[Super90]

Seems that maybe the cats were indeed too cold last time. After running the Redline Fuel System Cleaner through with a half tank of gas, I changed the oil. Today I got everything nice and hot and took it back for testing. No problem at all !

Thanks for the help !

[bubba966]

Seems that maybe the cats were indeed too cold last time. After running the Redline Fuel System Cleaner through with a half tank of gas, I changed the oil. Today I got everything nice and hot and took it back for testing. No problem at all !

Thanks for the help !

Good to hear it passed fine this time. Would bet good money it only failed due to the cats being too cold.

[Jake]

Bringing this one back from the past...

I just failed Arizona emissions yesterday with my 530iT. Here are the numbers:

HC loaded 180 (limit = 220) ~ pass
HC idle 253 (limit = 220) ~ fail
CO loaded 0.59 (limit = 1.20) ~ pass
CO idle 0.32 (limit = 1.20) ~ pass

The car has sat for 2 years with 1/4 tank of gas (with stabilizer). Knowing the gas was old my intent was to run it down a bit further and put a fresh tank in before testing. But as the day of running around unfolded I didn't get a chance to fill up. Could old gas cause a fail for hydrocarbons?

It ran great throughout the day so I figured the gas was ok. It has a fresh tank now and I'm debating retesting on Monday or booking it into the shop to confirm everything is good (or bad). What do you think?

While the car was down for those 2yrs I replaced the knock sensors, intake to head seals, and the plugs. The oil was fresh too. I did notice my crank sensor wire was frayed where it came out of the sensor. If it was causing a fault I'm fairly certain I would have noticed as I'd expect it to misfire, cut out or not run at all. It doesn't do any of that. In fact it sounds and drives better than my 540i/6spd daily driver. Very smooth.

Any input would be greatly appreciated.

Jake

[Jake]

Ok, I'm the idiot. It was just old gas. I had no idea it would make that big of a difference. Fresh gas brought HC down to 6 loaded and 13 @ idle (from 180 and 253 respectfully). That's a HUGE difference. CO dropped as well to 0.01 when loaded. It came up at idle though (0.75).

Just thought I'd pass that along.

Jake