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Hi, I took my 97 BMW 528i for a Smog and my vehicle. I paid $95 for a diagnosed and I was told my vehicle needs replacement of 2 catalytic converters.
My readings of the 02S12(V) and 02S22(V) are steady from 0.980 to 0.975. I though this meant catalytics are working find. Please advise. When I increase rpm to 2500 to 3000 readings are the same.
Please see attached Actron scanner readings. Readings are at idle on drive.
Also for some reason my secondary air monitor won’t complete. Two weeks back it was one of the first monitor to complete no matter how many times I reset monitors. Secondary vacuum and switch valve are wroking fine.
Smog Check Vehicle Inspection Report
%CO %CO HC(PPM) CO(%) NO(PPM)
Test – RPM – MEAS – MEAS – MAX – AVE – MEAS – MAX – AVE – MEAS – MAX – AVE – MEAS – Results
15mph – 1854 – 14.6 – 0.0 – 51 – 9 – 86 – 0.48 – 0.03 – 0.13 – 419 – 67 – 344 – FAIL
25MPH – 1819 – 14.6 – 0.0 – 35 – 6 – 48 – 0.46 – 0.03 – 0.12 – 706 – 62 – 114 – FAIL
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Its looks like your running rich with the o2 voltage being high.
If the secondary air system is not coming on that could be the rich
condition. Does the car have the check engine light on? if so post any
codes. see if this link helps you.http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
No, no codes. Vehicle fail smog 2 times with same results on 11/13 and 12/13. At that time the secondary air monitor was ok.
see if this helps.
It could be a bad cat but I would inspect the easier and cheaper things first. In my experience most of the time its worn out spark plugs or worn out coil will cause higher HC. I’ve also seen bad, leaky or really dirty injectors cause high HC. Injectors are not cheap but usually a concentrated mix of cleaner in the tank will revive them.
The best way to have a cat specifically tested is with an exhaust gas tester. Being a 97 BMW it may still have a test port on the exhaust manifold or down pipe – pre cat. A tech will take a sample there and compare to the tail pipe. If all the ignition components are in good shape and the exhaust samples are similar its the cat. Most good German car specialists will have one of these as a lot of older cars need the tester to properly set the fuel calibration.
All though in your case it may not make the difference to get you a pass you can lower your HC numbers by having the test done on a fresh oil change.
what does Upstream O2 sensor data state? .9V is very high for downstream indicating either a bad cat, o2 sensor, or rich condition caused buy a multitude of things.
as well as what these two fellows have stated here i think this test is a good idea.
[video]http://https://www.youtube.com/watch?v=9VZ5K8n5jj0[/video]
I’m not sure that video will help him much here considering the data. If his cat is bad it’s probably because it’s letting too much through rather than it being clogged. If it’s the cat, I’d say it’s because some of the screens in there are burned/rusted through and broken. Try hitting the cats with your hands and see if it rattles.
High hydrocarbons is unburned fuel. It’s usually caused by a misfire or too much fuel being injected. If the supplemental air system isn’t working it will cause the readings to be even higher.
The converters need the extra oxygen to light up.
What exactly is the supplemental air system? Are you referring to the secondary air? If yes, then the air pump that feeds air to the exhaust when the engine is cold is working find. Also the air vacuum valve and the vacuum switch are working. I don’t know why the secondary air monitor doesn’t complete. The only reason I think is because it hasn’t been that cold latetly.
I agree with wysetech…. unburned fuel.
I think the rich fuel issue is coming from bank 2. Why the SES light is not on with the O2S12 above .5 volts which appears to be fixed for a period of time I can’t explain. …but I know nothing about BMW’s.
I would check bank 2 fuel injectors pulse width modulation to make sure the ECM/PCM is sending the correct signal. If that’s ok; (Bank 2) fuel injector(s) leaking, spark plug(s), ign.wire(s) ,evap canister purge valve is purging fuel into bank 2 intake….but all should turn on SES light.
Very interested what the fix is going to be.
[quote=”quickNpainless” post=101544]I’m not sure that video will help him much here considering the data. If his cat is bad it’s probably because it’s letting too much through rather than it being clogged. If it’s the cat, I’d say it’s because some of the screens in there are burned/rusted through and broken. Try hitting the cats with your hands and see if it rattles.[/quote]
The video shows how to measure catalytic converter operation and efficiency. Many people have the misconception that if a catalytic converter is not working properly that it’s clogged. This is not true. It can flow perfectly but if the catalyst is not functioning properly it will not work efficiently. That’s the reason for the temperature difference when it’s in operation. If it’s doing it’s job, it will heat up as shown in the video. It can still flow fine and not heat up.
It’s also a common misconception that if you have an exhaust restriction that a clogged catalytic converter is the problem. While a clogged catalytic converter can cause an exhaust restriction, restrictions can also be caused by mufflers that have come apart internally, or double wall pipes that come apart internally. Not to mention damage to the pipes or other exhaust components.
Here’s a video that shows how to determine if you have an exhaust restriction.
Now to the original poster. Your readings indicate a rich condition. This could be caused by several things. I cover some of those things in this article.
http://www.ericthecarguy.com/faq/solving-automotive-performance-issues
In addition, the secondary air system supplies fresh O2 to the exhaust and catalytic converter for 2 reasons. The first is to help any unburned fuel burn up in the exhaust before it exits the tail pipe (to help cure a rich condition). The second reason is to increase catalytic converter efficiency. The more O2 it has, the better it can do it’s job.
That said, I think if you work on the secondary air issue, you may solve your emissions problem. That’s where I’d focus my diagnosis anyway. After fixing that, recheck the emissions readings and see what you have.
Good luck and keep us posted.
I thought the secondary air system works only at cold start. The S.A.S. Air Valve opens and the Air Pump injects extra air into the exhaust system to get air to the convertors after cold start up….. that’s the reason I was looking at other things than the AIR pump…..but I don’t know BMW’s
Check these links out
http://www.bimmerfest.com/forums/showthread.php?t=402816
http://www.bimmerfest.com/forums/showthread.php?t=415388After the first smog fail, I replace all 6 injectors, 6 spark plugs and boots. I also replace the CVV and hoses and vacuum hoses. Replace engine oil and oil filter. After that, I smog the car 3 additional times. Only the second time from all 4 smog test, the bmw PASSED the 25 miles but with border line HC. All the other 3 test HC was about the same (high).
The diagnosed cost me $95 but all the shop said it was that the car needs 2 new catalytic converters. What confuse me is that the readings on downstream sensors are not jumping up and down like the upstream sensors. Readings are steady.
I am going to do the laser thermo heat test and see if outlet is 100F hotter than the inlet on the catalytic.
If it fails this test I going to replace the catalytic converters with aftermarket ones. I just hope they don’t throw me codes because actually the BMW is not throwing any codes.
if the honeycombs in the cats are broken open instead of clogged then the cats won’t read an abnormally higher temp.
I’ll give you my opinion again for what it worth…just trying to help. I think after seeing your data bank 2 O2S12 above .5 volts which appears to be fixed for a period of time is the problem. Like you said the catalytic converters are trying to do their job because the voltage is steady…but high. Really just getting close and observing the catalytic converters; they should be very hot with an engine running very rich (high HC) like yours.
I would maybe get an second opinion on diagnosis …..try and find out what bank 2 fuel injectors pulse width modulation is doing to see if the ECU is doing it’s job…..maybe on a BMW the secondary air system functions when the engine is at operating temp….. and your’s isn’t.
Whatever the fix is please post.
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