NOx a problem????? Not anymore!!!!

[JHZR2]

First off, thanks to all who have helped me on here trying to figure out my NOx problem.

Its amazing what an OE cat converter can do for your emissions. An aftermarket converter, day one, is abot as good as a 100k mile OE unit - seriously. And Im not talking about today's improved heterogeneous catalysis, no. Im talking about 1991 technology.

So, my previous failure with my Dinan (CARB approved) chip was:
NOx: 2126 (standard = 1134)
HC: 161 (standard = 146)
CO%: 0.54 (standard = 0.82)
CO2%: 14.1
O2%: 0.5

After this gross failure, I took out the dinan chip, and things got worse, up to 2700 ppm NOx.

I checked madly for intake leaks, thought about lean misfires, etc... No dice. Some said that my chip was making the car run with poor emissions, though I knew from the past (I had been borderline failing, around 1150 ppm NOx, since 2003) that this wasnt the case. When I put in the aftermarket cat, my numbers didnt even budge from those that were on my OE cat that had 100k on it.

Well... (drum roll)... $1200 later, and after a new, OE, BMW cat, freshly imported... my numbers are now:
NOx: 49
HC: 3
CO%: 0.00
CO2%: 15.0
O2%: 0.0

Thanks all for the help and assistance, as well as helping me to stay sane while troubleshooting what was a perfectly operating automobile...

Fortunately Ill not have to worry about emissions for a LONG time now!!!!

Best regards,

JMH

 

[Quest]

LOL! Thanks for the update on your latest situation.

I suspiciously wonder how much "precious metal" is in the aftermarket replacement cat to begin with? Could it be just a half-used matrix core in a new steel shell job? Humm....very suspicious indeed.

Q.

 

[tom slick]

IMO you engine still has issues that your new cat is covering up. maybe the factory used the cat to cover up that fact but a properly tuned car will pass nox with no cat. in 1991 many cars still came with cats that only dealt with HC and not nox.

was your old cat plugged?

 

[Lonnie]

I went from fail to pass on NOx with a dose of Auto-RX.

 

[JHZR2]

Quote:

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I went from fail to pass on NOx with a dose of Auto-RX.

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I didnt, twice... Auto Rx is some great stuff, ut not the cure all for every problem...

JMH

 

[JHZR2]

Quote:

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IMO you engine still has issues that your new cat is covering up. maybe the factory used the cat to cover up that fact but a properly tuned car will pass nox with no cat. in 1991 many cars still came with cats that only dealt with HC and not nox.

was your old cat plugged?

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my old cat (the OE) wasnt plugged, nor was the mineke one that I swapped in in 2005.

A car without a cat may pass nox, but it likely has an EGR to keep combustion temperatures low. This car is designed to be power dense, have a simple setup emissions-wise, and have relatively advanced timing... all of this equates to NOx, which MUST have a proper cat to clean it up. If they wanted it to be clean regardless, they wouldnt have such a good cat, and instead would have slapped an EGR onto the engine... they didnt.

Maybe there is something wrong... but if there is, neither my mechanic nor I could find it. Any suggestions??? The car runs wonderfully, but I am always for making sure it really is 100%.

Thanks!

JMH

 

[Virtuoso]

Holy cow! $1,200 for a converter! I've driven cars worth as much *grin*

Glad you got it fixed up though! Mother nature is happy now.

 

[JHZR2]

For a car worth keeping, $1200 is a worthy investment to have the repair done so that it will last and not be a headache for a long time. at 109k, this car has a LOT of good life in it, and as my commuter car, I feel it important for it to be enjoyable for me to drive, thus why I like to keep it well...

I agree though... Pt, Pd, Rh arent cheap metals, but it is a LOT for a washcoat of this stuff on an alumina monolith in a mandrel bent pipe...

JMH

 

[trixman]

If you know your car is a CAT clogger, I would take preventative measures to keep it from happening again.

Clean that C chamber and cat with something you feel comfortable using thru a vacuum line before every or every other oil change.

 

[JHZR2]

But the car is not, and never was a cat clogger. No issues. Compression readings are always consistent, and when I had the head off to fix an opverboard coolant seep, everything was VERY clean...

JMH

 

[Laminar Lou]

Glad to hear you got it fixed. It was interesting to read through your problem solving process. My money was on fried cat, but I completely agree with your methodology to diagnose the problem.

Question: Did you have to pay for the test each time you failed?

 

[Quest]

lol trixman!

If the car/vehicle in-question is a cat clogger of some sort, I would look into things deeper to see what's the root cause of the matter, instead of assuming that the combustion chamber is always coked up and in need of carb cleaner, combustion chamber cleaner, Berryman, etc.

Hope you get my drift...

 

[JHZR2]

Quote:

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Question: Did you have to pay for the test each time you failed?

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Fortunately not... in NJ we pay 7% sales tax, but at least our inspections are free...

JMH

 

[Laminar Lou]

Quote:

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Fortunately not... in NJ we pay 7% sales tax, but at least our inspections are free...

JMH

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Glad to hear it. We pay 8.25% sales tax in Los Angeles and we get to pay for the smog test. But I think most places don't charge you if you fail.

 

[trixman]

Quote:

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lol trixman!

If the car/vehicle in-question is a cat clogger of some sort, I would look into things deeper to see what's the root cause of the matter, instead of assuming that the combustion chamber is always coked up and in need of carb cleaner, combustion chamber cleaner, Berryman, etc.

Hope you get my drift...

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For me NOx is not a problem until it's time to get a sticker.

So cleaning is a quick and dirty way to lower it, without throwing big money into something like a CAT.

It is the spendthrift way to save your money and delay the a major purchase ie your next car.

I did this for my 91 corolla every 2 years for my RI inspection. I figure I kept things rolling on the rolla an extra 4+ years.

DO you get my drift now?

 

[JHZR2]

A 91 BMW is a MUCH more valuable car, which, no offense, is worth keeping vice a corolla.

at 109k it runs perfect. No reason not to throw $1200.

the difference between a jalopy and a new car is not its age, its how much money you put into PM and keeping things like new.

JMH

 

[andyd]

I wonder what caused the cat to fail. 109k is nothing for this engine. My 528e passed at 330 k miles on the original cat. For test purposes, I used 93 octane doped with Viscon, but I dont think this had much effect. I also gave the car a 45 minute Italian tune up just prior to the test. The NOx reading was less than 1/2 of the max allowed. I am thinking that your stall and crawl commute is the cause. I recommend an occasional run at high rpm to clean out the carbon.

 

[Quest]

lol andyd!

with water jacket controlling your combustion chamber temperature pretty much to a very narrow thermal range, what makes you think that occasional run at high rpm will clean out the carbon? Besides, what makes you think that it will come with boatloads of carbon inside the combustion chamber to begin with anyways?

I always found that there are people who tends to jump in quickly assuming/accusing that there are heavy deposits inside the combustion chamber of an engine, and will immediately prescribe anything from seafoaming the chamber overnite to WOT/high rpm to clean it. Truth is, with closed loop controlled EFI engines and properly functioning ignition timing and tuneup, the only time you are getting loads of unburned carbon is the time when you are regularly doing short trips (
To clean out the combustion chamber is to give your engine a proper tuneup, run a few full tanks of high detergency gasoline on the highway for 6~8 hrs.

Bottomline: it's not the RPM that makes the difference, it's the extended controlled operating condition (cruising down the hiway with moderate engine load) that cleanse the engine, period.

 

[c502cid]

A 91 BMW is worth more than a Corolla? How do you figure? A 91 BMW is just a used car. If you love it and want to keep it fine, but putting down others, even if you can "justify" it in your own head isn't quite right.

 

[JHZR2]

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A 91 BMW is worth more than a Corolla? How do you figure? A 91 BMW is just a used car. If you love it and want to keep it fine, but putting down others, even if you can "justify" it in your own head isn't quite right.

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Im not trying to go there or go down that path... but I think that few will argue the point that (a) the market for older BMWs is far different from that of similar aged toyotas (b) the resale values of BMWs of that age are higher than toyotas of that age (c) there is far more of an enthusiast market for ANY bmw of ANY age, than that of most toyotas, especially ones of that vintage.

I have no problem throwing dollars at a car that looks, runs and operates like new, is a blast to drive, and has a strong following around the world as a great car to use even today for everything from a commuter to a track car. Sorry, maybe my style isnt the same, but for a car that I deem worth keeping (whatever it is), I will not perform a "quick and dirty" cleanup or fix. its bad economics to put good money after bad (i.e. a car that will be traded in in a few years or miles or whatever), but for a car that will not be traded in any time soon, and shows absolutely no signs of biting the bullet any time soon, why not sink the dollars to DO IT RIGHT, have it correct, and be 100%???

Someone planning to make repairs for something so that it is good enough and the money can be saved for the next car's purchase (and thus pay for its depreciation) is clearly different from someone that sees a LOT of useful life from their like new vehicle, and barring total destruction, has no reason not to keep it for another 10+ years and 100k. It doesnt matter if it is a BMW or a hyundai - if its in great shape, and has no reason to not have a LOT of useful life left, its worth doing the PM and repairs to keep it on the road, preventing the most costly thing of all - depreciation.

JMH