Rotten-egg smell is hydrogen sulfide (H2S) which smells different than sulfur dioxide (SO2) although both are obnoxious. H2S is a reduction product; SO2 is an oxidation product. Both can come out an exhaust pipe, but not at the same time. It might only be an indication of the sulfur content of the fuel.
Insightful: you are correct. My chemistry is 40 years in the past.
"Collectible Classic: 1986-1989 Acura Integra"
A Collectible Classic… Boy am I getting OLD… I watched more of these rust into dust out here on the East Coast than I can even remember. Ive owned a few as well. Always liked them. Who knows with their attrition rate as high as it was/is…the price could skyrocket due to how rare they are becoming. I wouldn’t hold my breath tho…
Blackbird
Don’t you think it is all about maintaining it? Mine is rarely rusty with original paint. A 3rd gen Type R went for $43k on eBay in 2015-14 with under 20k miles and was always garaged.
Maintaining it? Depends where you live…out East…on the Coast or the Rust Belt Proper? They dont stand a chance. Unless you are nutso about washing it every week or DAY…have a garage, dont drive in the rain…or Heaven forbid…the Snow. When you intentionally throw SALT on the roads and then drive a car thru it…you might as well go for a ride in the Ocean everyday and see what transpires.
We on the east coast know dern well what can and does happen to the most rugged of vehicles…and rugged the Acura aint…not in the East coast salted road sense. Honestly…Nothing can stand our road conditions in winter…even Large Trucks succumb to it… Rust never sleeps…remember that and Rust lives out East, I forget his actual address…but he’s from the East Coast I promise you…
Out West? Sure…that’s why we look for desert cars here on the Right Coast
Any vehicle can survive with the correct care… Time has proven that almost any make and model can become desireable… There’s a weirdo for every model I say…Even the K Car has a following…The Gremlin, and so on… Loving an Integra isn’t weird to me…they were good cars really…and the ones from the JDM market were much hotter as usual…
You cannot even find many or any 1st gen Tegs out here where I live…they have rusted into oblivion.
Blackbird
O2 sensor failed on rise time - when it was replaced, emission became a border line pass. So tomorrow, cat will be taken care of.
You have 2 O2 sensors… Replace BOTH then move on to the Cat… Not the other way round
People jump to the CAT way before they should typically. Why? Bec when one of the O2 sensors fail…it posts a Cat efficiency code… Why? Because the two sensors work in tandem… The pre cat sensor sniffs the exhaust…and makes a note of the reading…the second Post cat sensor does the same…the result of this comparison should be a drop in emmissions at the second O2… If the second o2 sensor is out to lunch or cannot read properly…the ECU sees no drop in emissions after the exhaust flows thru the CAT…and labels the cat faulty… When in reality the o2 sensors are to blame. Happens all the time.
Until both O2 sensors are brand new…do not move on to thinking the cat is bad… Exhaust leaks can also muddy the waters on how the o2 sensors are reading. There MUST be a differential between the pre and post cat O2 sensors…and no exhaust leaks…at all.
Blackbird
In what year did Honda/Acura begin using a downstream oxygen sensor? Not 1987.
Yeah 87 Acura Integra only has one o2 sensor
Oh yeah…OOPS… I forgot what year the vehicle was for a while there… LOL
Then again…this is a CA emissions vehicle No? Why do I think there was a difference? I know instead of using 2 like the rest of the country on most vehicles…CA uses 3…
At any rate here is a quick Cheat Sheet when it comes to NOx emissions…
What causes high NOx (nitric oxide)?
NOx… if your car is registered in an enhanced area (an area that requires testing of NOx), you may run into this problem. High NOx is caused by high combustion temperatures and pressures. Problems that can cause high NOx include:
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An inoperative EGR system. The EGR system was designed specifically to reduce NOx; that’s it’s only function. The EGR, which stands for Exhaust Gas Recirculation, allows exhaust gas to enter the combustion chamber through the intake. The exhaust gas has a cooling effect on the combustion chamber.
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Over advanced ignition timing. The more advanced the ignition timing, the higher the combustion chamber temperatures.
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Overheating. If the engine temperature is too high the NOx emissions will go up.
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Lean air/fuel mixture. If the air/fuel mixture is too lean the combustion temperature will go up.
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Compression over specification. Normally when we think of engines aging we think of the compression going down. However, there are a couple of ways the compression can increase as the engine is used. One is carbon buildup on the tops of the pistons. When carbon forms on the tops of the pistons, the combustion chamber area decreases and the compression ratio increases. The carbon can be manually scraped off the tops of the piston to correct this problem, but that would require disassembling the engine. You can check the tops of your pistons thru the plug hole with a long screwdriver and some solvent…the solvent will help the carbon…if there is any to stick to the screwdriver so you can see it. You can also feel it with the tip of the driver…and you can look down the hole with proper lighting…and see if its an issue. In this vehicle…I would do a compression test also…
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Mysterious reasons. Sometimes NOx is too high and there’s no obvious cause: the EGR works, the timing and advance work normally, the engine temperature is within range, the air fuel mixture is good, and the compression is within spec… When this happens you can try a little tweaking. If there are two thermostats listed for the car, use the cooler one. If there are two spark plugs listed for the car, use the cooler one. Retard the timing 2 degrees (the maximum allowed). Clear out the EGR passage even if the passage seems fine.
I think you have gone down this list…but never hurts to be sure…
Blackbird
See the link for the photo that compares before and after a Magnaflow cat (but after NTK O2 sensor)
HOLY COW… Thats a Nice Report card man. So what was it in the end…a combo of O2 and the Cat ? Perhaps the O2…slowly failing over time just taxed the matrix inside the cat and coated it with carbon…then the new cat and it cleaned right up. Its good you did both and in that order
Anyhow…Congrats
So how often should u change the O2 sensor? I never changes these things! Have a 2000 Integra with 110k - it prob has two O2 sensors.
I am sure the answer is when they go bad, so I have 177k miles, and watching and waiting, preemptive replacement might be a good idea, but have not been convinced. but it sure can’t hurt.
@Barkydog - thanks for the clue - but in my case, it partially failed - only way to know is to take it apart and put it in a Oscilloscope. The m/c said 100k is roughly the lifetime - I hope changing it at 150k would be a good idea if it is a Honda and the sensor does not have a heating element. On a second thought if it is an OBDII, will it notify you of a failure even if it is partial failure.
@“Honda Blackbird” - You say “slowly failing over time just taxed the matrix inside the cat and coated it with carbon” - is that how it works - are u sure?
No but it theoretically makes sense… Cats usually last the life of a vehicle normally. Then again…what is the typical “life” of a vehicle in years? Your vehicle is surely pushing the normal lifespan of what most people experience… Perhaps if we all kept cars 20+ yrs we would all find that the Cat fails near that mark. If NOT…then sure…a failing sensor that controls your fuel mixture falling out of its ability to properly set that mixture could indeed run so rich for so long that it overwhelms the Cats ability to scrub the exhaust.
So you have time and…time basically… Pick either theory…they could hold water equally if you ask me.
Blackbird
When I sold my '88 fuel injected Accord at 220k miles it still passed the dyno emissions test by a wide margin.
Still had the original converter and O2 sensors (both pre-cat).
@“Honda Blackbird” - thanks for your various comments - an article on Meinke also says that bad O2 sensor can affect the life of cat.
Secondly the invasive test shows the old cat was 49% efficient for NOx - so the new ones are 100%?
@Barkydog - I think that with a device like this - “BAFX Products 34t5 Bluetooth OBDII Scan Tool for Android Devices” you can check the O2 sensor even when there is no CEL - There are cheap OBDII devices but it is a gamble. http://www.amazon.com/BAFX-Products-34t5-Bluetooth-Android/dp/B005NLQAHS
There are better software on Google Play. Cost adds up - maybe just changing the O2 is better.
I can notice the improvement in performance - believe that the gas now burns better. When the gas tank become empty, I could figure out any improvement on gas mileage.