My '86 XJ6 was sold new in California, manufacture date was July 1985. I’ve owned the car for 21 years now, never had a problem passing emissions testing, which is done every two years, The car is due for its exam now. Yesterday I went to an inspection ‘test only’ location. My regular mechanic recommended him, and he said he would do a ‘pre-inspection test’ for me at no charge. He put the car on the dynamometer and ran it at 16 miles per hour, he didn’t do the second part of the test which is supposed to be at 25 MPH. He gave me a printout of the result, and said my car would fail because the maximum allowable NOX emission at that speed is 742 PPM, and my car has a reading of 1209 PPM this time. I’ve never had such a high reading ,Usually I’ve gotten between 400 & 500 PPM in the past. He said I might need a new catalytic converter, but I’m skeptical. my HC reading was 17 PPM (maximum allowed 82), CO was .01 %(maximum allowed .10%), and CO2 percentage 14.9% . so, other than nox, all my readings are acceptable.
Jaguar dealers, ‘Original Jaguar’ , and SNG Barratt do not even carry California standard catalytic converters. This morning I did a bit of research on the internet, and found there are several manufacturers which still made California compliant converters, some even with a direct bolt on fit, but at a hefty price. Even if I were to bite the bullet and make the purchase, (do I need front and rear items?) is it safe to say these would solve the failure problem? This morning I went to another smog test only station and chatted with the owner. He said it may not necessarily be the catalytic converter, maybe there is another problem , maybe a vacuum leak somewhere. I don’t think there is, my idle has not risen, and, as mentioned before, all my other results are acceptable. When I pressed him further, he did admit that my nox readings may have been high because I had the car tested on a very hot day , and I had the engine running longer than I would have liked in the hot sun before he put the car on the dynamometer for testing. The guy I saw today said I could make an appointment to see him first thing Monday morning at eight o’clock. At that hour, temperatures at his facility would be only 65 degrees, and I’m only live three miles away from him. Of course, he wants $$$ for the preliminary test, and more $$$ if he does the actual test afterwards. He seems like a bit of a crook to me, but the thought of possibly passing on a cool weather day makes me consider just having him do the actual test first thing Monday morning. I do remember I had a different ('87) XJ6 adjusted about eight years ago, also on a very hot day. The mechanic I worked with at the time sent me to have the car tested at an inspection facility near him. It failed with high nox readings. He told me to drive home to my side of town, which was 25 degrees cooler, go to a smog station, and have it tested again. I did. It passed. So, should I gamble on the Monday morning test, then? If it fails, then what do I do? There is a company called ‘Magnaflow’ which makes California compliant catalytic converters, with a bolt on direct fit. They make the rear one as well. If the car fails the test Monday in cool weather, should I assume it’s a catalytic converter problem, and if so, should I replace the front one, or the front & rear as well? My car is 32 years old, the catalytic converter on it appears to be original and yet I’m still concerned that after only two years and only 3000 miles, my car would have unacceptable nox readings compared to that short time & mileage interval. All advice will be appreciated. Thanks…
Mel R.
The use of old formula motor oil with high ZDDP content can ruin catalytic convertors.
When I bought my 2000 S-Type in 2009 it failed the first EPA test, and I put on aftermarket cats, which got it past the first test but failed about 2 months later. My car has OBD-II which gives warning messages when emissions failures occur. Presumably the previous owner had been using ZDDP oil. I sent back the aftermarket parts and bought original cats from the Jag dealer. I also changed the oil and filter, ran it a few minutes, and changed them again. It has been good ever since, for 90k miles.
Odd, in one way, yes. In others, not so much.
-
California compliant cats cost a lot more than those acceptable in any of the other states. An entire story there.
-
I don’t understand the ambient temperature effect on NOX production. A google on that might be interesting.
-
I read that it is best to have a cart hot before the test. So, I usually go on a freeway blast then straight to the test place.
-
It could well be that the cats were marginal the last time on your car, and gone this time.
-
I managed to ruin a pair of new cats on my lump rather quickly. Don’t ask.
-
Go shopping at local muffler shops. One local did my lump twice!! Still painful but the better of the
options. -
My Jeep’s cat went out at just over 200 miles. Same shop
welded in another. I did find a CA compliant bolt in, but pricey. -
I read a Craigslist add for a Jetta. For parts, cheap. all good except the cats. owner not willing to spend the $'s for CA compliant cats. I get it. My daughter’s VW Passat had ignition
issues. I fixed those. But, it just snuck by it’s last SMOG and every indication existed that it would flunk this time. I checked pricing. Oh yeah, CA cats, bigger $'s than others. Bye, bye Passat. Traded in to Enterprise. Nissan, this time around???
Carl
I hope that worked, e
rrant fingers already!!!
I did a google search, found several ‘sources’ for info on how to pass test. One of them clearly stated ’ a car tested early in the morning with outside temp at 60 degrees with high humidity will do much better than a car tested in the middle of the day with outside temps of 90 degrees… we shall see…
**
I was musing on your CO reading, Mel…
In principle; high NOx readings indicates that the engine is running too lean, leading to higher combustion temps, which increases NOx. Sort of confirmed by the ‘better’ results in cooler weather. Lean mixture is also indicated by the very low CO reading; nominally mixture is adjusted to somewhere between 0,5 and 1,5% - while, somewhat odd, the permissible level in your test regime is 10%.Ie, you may fatten mixture considerably to reduce NOx…
However, the fly in the ointment is that, when Lambda system is fitted, it deliberately adjusts the set mixture - mixture setting is done with the O2 sensor disconnected. And of course, if the levels are measured at the tailpipe, the converters has influenced readings…
Certainly, new cats may solve the problem - but I wonder if you have a fuelling/mixture problem…?
Frank
xj6 85 Sov Europe (UK/NZ)
**
Frank
The emissions test is performed every two years. Since the last test two years ago, the car has been driven less than 3000 miles. Before the previous test, relying on your excellent advice, I replaced the AAV valve with a used one, which did solve the problem I was having at the time with difficulty restarting the car after it had been driven and parked for twenty minutes. The car now runs well, good acceleration, acceptable idle, decent gas mileage figures. In December 2015, while having the water pump replaced along with belts and hoses, I had the thermostat replaced as well. This new thermostat opens at 180 degrees F, as opposed to some which open at 195 degrees F. I asked a technician at a local Jaguar dealer service department if the new thermostat would present any problems, he said no, the factory allows for the installation of either one, and the 180 is probably better for the warm climate in which we live. Before the thermostat was changed, temp guage usually went to just below 90 C. after car was driven to operating temp. With the new one, guage settles to the notch just below 90. On a warm day, after about twenty minutes of driving, the needle moves closer to 90. On the day I had the preliminary test done, last Friday, the car sat in the hot sun , outside temperature 90 degrees F, for several minutes before the car was tested on the dynamometer. By the time he drove the car on to the dynamometer, I could see the temp guage was just ABOVE 90. Could this indeed be the culprit for the failed NOX result? As you might imagine, I’d rather not have to replace the CATS . The CATS on the car are the original ones which came from the factory when the car was built in July 1985. The car has 92000 miles on it. Is it possible the CATS have outlived their usefulness after 32 years? Or, in one last ditch effort, shall I have the car tested again at a different location early in the morning on a cool day? If so, I know if the car isn’t warmed up sufficiently, it could fail as well. What temperature should the guage show before the car would be warm enough to test? As always, thanks again for your advice.
Mel R.
I spoke with a specialist today. When I gave him all the readings for HC,CO, and NOX, he said he does not think the catalytic converter would have to be replaced. He thinks that either the ignition timing is off, or there might be a problem with the vaccum on the distributor. He said he couldn’t look at the car for at least a few days, and based on his extremely high hourly rates, that’s ok. If these two items are the culprits, I’ll wait until my regular mechanic can look at the car again. He adjusted my timing two years ago, and the car passed. This ‘new’ guy says perhaps he didn’t sufficiently tighten the distributor, and by now the timing may be off. What to do?
Hello, My experience with California smog laws was with a 78 Olds Cutlass that had a 350 Chevy engine. Every two years to pass I had to retard the ignition, hook up all the plugged vacuum lines, lean out the carb till the car barely ran. If that did not work I used a fuel additive. I used Lucas ethanol fuel stabilizer in the gas tank then got the engine good and hot and did the test. It worked for my car. Go to a parts store and explain your smog issue and see what they recommend as a fuel additive for smog. High NOX does not sound like a cat problem so try the less expensive things first. Pete
Thank you. I think you’re right. I just spoke with another specialist, he had me read him all the numbers. From 2015 two years ago until now, two interesting things occurred. While the NOX levels soared. from 496 PPM to 1211 PPM, the CO level plunged from .10 two years ago to .01 three days ago. He said a dramatic rise in NOX levels coupled with a sharp decrease in CO indicates a vacuum leak somewhere in the system. Now the search begins…
I went to the garage and proceeded to search for the mysterious leak. I remembered I had removed the engine breather hose on top of the front of the engine a year ago to install the missing ‘mesh capsule.’ Even though the hose appeared to be tight, I found a clamp, placed it on the surface where the rubber hose meets the housing, and tightened it well. Then, I went on to the hose which runs from the air filter housing to the metal rail on top of the front of the engine. The hose appeared to be a bit crimped in the area where it emerges from the housing. I removed the hose completely, then massaged it until there was no more crimp, then carefully installed it. Next , when I re-installed the air filter housing, I took great care to make certain the clamps holding the air cleaner housing to the air flow meter were straight & tight. Next, I moved on to the convoluted hose which runs from the back of the AFM to the throttle body checking all connecting surfaces for a good tight fit… Of course I made sure the thin rubber hose attached to the surface near the AFM was securely fastened as well. Once all this was complete, I got in the car, started it up, and hoped for the best. I warmed the car up to operating temperature while running the a/c at the same time to simultaneously warm the car up faster while cooling me off. Once the temp guage appeared to have reached operating temperature, I turned off the a/c.When I looked at the tachometer I was pleased to see the idle now sat between 800 & 825. This was great news. For the past year, the idle in neutral at operating temperature ran just above 900. With it now hovering closer to 800, I believe I have rectified the leak, wherever it may have been. Perhaps I’ll take it in to have the complete smog test tomorrow. Anyone think it might pass this time?
Mel R.
**
Time will tell, Mel…
However, the air leak possibility pointed out by ‘another specialist’ is highly relevant - it will cause the engine to run lean, enhancing NOx generation - and indeed rise idle. Or the other way around; drop in idle after your ‘sealing’ work implies it was an air leak, now eliminated, or reduced…
Whatever else you may plan to do; before or later you have to take the test, or pay $$ for another pre-test - and I think now is as good as it gets…
Frank
xj6 85 Sov Europe (UK/NZ)
**
Good work. In view of all you now know about Co and NOX and the change in idle RPM, I would go for broke. Test it.
I gotta say I learned something. Neither lean nor rich, but just right to get past SMOG!!!
Still a bit querulous as to the relation of high ambient temps and a Smog test failure.
And ugh, My Jaguar is up next month!!!
Test station choice?
Carl.
Great news! I took the car in for a complete smog check today…yes, it passed, as they’d say in New Zealand, with ‘colours flying.’
Not only did it pass, but it passed with numbers even better than I got two years ago. Maximum amount of NOX allowed is 742 PPM. I got 480. Maximum HC allowed is 82 PPM, I got 14. And, strangest of all, the CO % at both speed levels was only .01%. I am thrilled. Thanks to all of you for your wise words of advice…
Mel R.
**
Good work well executed, Mel…
The low CO means your converters are working as they should - but your mixture may still not be optimal. The CO is from incomplete combustion - distorted by the converters, as is the HC coming from unburnt petrol. The NOx comes from the nitrogen in the air - oxidised by the high temps in the combustion process.
The petrol also cools the combustion temps - and lean mixture means higher temps, and more NOx. The chemistry during combustion is rather complicated, basically carbon in the fuel being oxidised creating energy - like burning coal. But since neither fuel nor air is pure carbon or pure oxygen - unwanted byproducts is the result…
But who cares when you pass…
Frank
xj6 85 Sov Europe (UK/NZ)
**
‘Who cares when you pass?’ Right you are…thanks again.
YUP, ditto, It runs well, it passed. Two years of peace. Drive it.
Enjoy !!!
Carl