Failed emissions - High NO

[cmk]

Was rather suprised to fail my emission test today.

ASM2525 Test
HC : Limit 52 Reading 0
CO : Limit 0.29 Reading 0.00
NO : Limit 385 Reading 626 (FAILURE)
RPM : 1661 (how do they get this ?, they didn't open the hood)

Curb Idle Test
HC : Limit 200 Reading 0
CO : Limit 1.00 Reading 0.00
NO : N/A

I went through the archives and looked at some of the other threads but didn't find anything definitive.

The general consensus seems that it's due to running hot, yet the temp is pegged at center, put in a new rad and full flush last fall. Temp is fine.

I've usually taken it to a dealer (where it passes no problem), but this time i took it to a small hole-in-the-wall around the corner. Is there any way they could have screwed things up ?

[colo525i]

Don't see how there could be 0 HC and CO readings, those should both be there. Unless your car is running on water laced with nitrogen fertilizer! Try taking it elsewhere, those numbers make no sense.

[Jon K]

to get the rpm they use an inductive pick up that picks up rpm pulses from cars electronics.

[attack eagle]

certainly.
How does it fail to emit ANY carbon monoxide OR HCs at 1600 rpm? Does it run on magic blueberries or something?
Go elsewhere , I think they are looking to make rent this month.

[cmk]

I agree that the 0/0.00 for HC/CO are weird, but the last test (2004) had the same but with NO = 286.

The test before that (2002) had HC/CO/NO = 3/0.00/0 ... so i can't seem to win for tryin', i find an NO = 0 equally as improbable. Although in 2001 both cats were replaced (warrenty).

Each test was done at a different place (all before current at dealers).

I'm going to replace the plugs/oil/filter this weekend.

If i can get some O2 sensors from Bruno (for a reasonable $) i might replace those as well. Looking back through service records they've never been replaced - car at 191kkm. From what i've read the O2 sensors wouldn't give the results i'm getting, so it's more preventitive than maintainance.

[yaofeng]

Get GTP (Gaurantee To Pass) from Pepboys or any parts store. What have you got to lose for $9.95?

[SnakeyesTx]

Worked for me on a beat down 91 caddy with the 4.9 V8 with bad o2 sensors, bad cat, and bad MAP :D

[cmk]

I've been thinking about doing that but i'm concerned that they will gunk up the injectors and/or plugs. I'd rather fix, than patch, the problem.

[BillionPa]

0HC and high NOx = lean running, get new O2 sensors and fix you vacuum leak!

[cmk]

From what i've read a failed O2 sensor will cause it to run rich.
http://www.autohausaz.com/bmw-auto-parts/bmw-emissions-oxygen-sensors.html

[BillionPa]

O2 sensors can fail for different reasons.

[Gayle]

Here is the definitive explanation from Bill R.

You don't mention if you had the car really really hot before the test. I think the cat has to be something like 500 degrees to work effectively. You may need to have an arrangement with the testing place that they will test it as soon as you drive up so it doesn't cool off--then drive the hell out of it.


Nox is caused by high combustion chamber temperatures, typically high performance cars with large lift cams and high compression also had very high levels of nox. Anything you do to reduce the amount of energy being produced will lower your nox levels. If your running regular instead of premium your nox will be higher since theres more energy being released in regular since it burns more rapidly, so running premium will make a little difference. Running the 10% ethanol blends will also help since this reduces the amount of power in the fuel also. which will lower combustion chamber temps. The cat is going to make the biggest difference, so make sure its completely warmed up and don't shut it down any longer than needed while waiting to be tested.
If its badly in need of a tuneup that will make a difference, anything that causes pinging will raise nox also.

[632 Regal]

with all them readings of zero, I would suspect the place you took it to. Follow Bill R's advice next time, get it to pass and take that receipt to the first place the F'd you and demand your money back.


Was rather suprised to fail my emission test today.

ASM2525 Test
HC : Limit 52 Reading 0
CO : Limit 0.29 Reading 0.00
NO : Limit 385 Reading 626 (FAILURE)
RPM : 1661 (how do they get this ?, they didn't open the hood)

Curb Idle Test
HC : Limit 200 Reading 0
CO : Limit 1.00 Reading 0.00
NO : N/A

I went through the archives and looked at some of the other threads but didn't find anything definitive.

The general consensus seems that it's due to running hot, yet the temp is pegged at center, put in a new rad and full flush last fall. Temp is fine.

I've usually taken it to a dealer (where it passes no problem), but this time i took it to a small hole-in-the-wall around the corner. Is there any way they could have screwed things up ?

[cmk]

Followup :
So, i failed the first test Wed.

Fri. i added a bottle of Redline Engine cleaner to full tank and did several hours of highway driving (~300km), got 8.8 l/100km.

Sat. i changed the plugs, oil filter, oil (Mobil 1 0W40).

Sun. did another highway drive (~400km), got 8.9 l/100km.

Mon. took it into dealer for another emission test - failed:
HC - 7, CO - 0, NO - 585 (NO down 50 from 635 on first test).

Was told that it was likely cats and that if i got a diag that showed repair was over $450 i could get it re-tested and get a conditional pass (enough for plate renewal, but can't sell car). Seeing as the dealers want $1600 for each cat this shouldn't be a problem.

Managed to get it in for a diag., mech came back and said everything was within spec - WTF! He tested MAF sensor, O2 sensors, looked for leaks, checked plugs (said i installed properly), checked in/out temps on cats, ... .
He, did mention that it took just over 8 min at 2500rpm to warm cats up to temp. He suggested cleaning air intake (a bottle of cleaner and 3hrs labour).

Tues. took it back for retest (with diag showing repair costs over $450), planning to get a conditional pass. Talked to head mech and relayed diag tech findings. Mentioned warm-up time. He took it out for a couple laps around the block to warm it up before testing. It passed ! HC - 7, CO - 0, NO - 378 (limit 385). I was floored that getting the cats to temp knocked 200 off NO reading.

Moral of the story: make sure you test them cats hot.

[Traian]

Semi-hijack:

I just did a similar quantum-dot pass a little while ago, with HC just on the limit (52 ppm). I thought i had a possible intake leak, which made this seem odd, and the readings have crept up every test for the last 6 years (I have previous readings as well). Once every couple of weeks the CEL will come on for a few secs. Now I passed, so I'm good legally for the next 2 years, but still interested in an answer...