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Discussion Starter #1
How many catalytic converteres are there on an Insight?

If there are more than one, has anyone tried to take out at least one of the catalytic converters (closer to the b-pipe)?

Also, does the ECU check for the presense of all catalytic converters?

If so, how many O2 sensors are there on an Insight?

TIA.
 

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<replied inline>

How many catalytic converters are there on an Insight?

<reply>
Two. One standard. THe second is a NOx absorptive type which requires two ceramic honeycombs combine in one unit.

If there are more than one, has anyone tried to take out at least one of the catalytic converters (closer to the b-pipe)?

<reply>
Removing a CAT in addition to it being ILLEGAL will almost certainly de-tune the Insights MPG potential. If you want performance I'd recommend a different car.


Also, does the ECU check for the presence of all catalytic converters?

<reply>
All OBDII cars monitor for the presence and efficiency of a CAT. Remove it and you will be operating in a less than optimal performance mode. Further ILLEGAL modifications will not be discussed.


If so, how many O2 sensors are there on an Insight?

<reply>
Two. One standard for CAT efficiency monitoring. The second is a LAF type so it could be said that there are three built into this one unit which allows readings over a much wider range of fuel air mixtures than a single sensor can operate.
 

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Agreed. You'd get error codes really quickly. All new cars monitor emission and converter functionality through the OBD. In fact Arizona's emissions test for 96 and newer vehicles is to just plug in to the OBD, if there are any codes you fail and they won't pass you until you get it repaired. Even if the vehicle coould pass the gas analysis test. It wouldn't suprise me if more states followed with this.
 

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Discussion Starter #4
I was thinking of getting a high flow cat (in place of 2nd cat) to open up the 3cylinder engine. Someone in this forum mentioned getting better MPG with an intake and exhaust dump/hole while getting a bit more pep.

But, if it severely effects the emission, then I guess it would be a moot point. I'm guessing that Honda spend many hours getting it to put out nearly zeron emission.
 

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Cosworth said:
<snip>

Someone in this forum mentioned getting better MPG with an intake and exhaust dump/hole while getting a bit more pep.

<snip>
If you remember the thread the poster's LMPG is rather low _and_ he honestly states in other threads that he doesn't really try for maximum MPG.

So maybe his modifications have improved MPG for his style of driving. Or maybe it was a wishful right foot <g>. Without dyno testing its almost impossible to say for sure.

The modifications have almost certainly reduced the maximum MPG potential his Insight is capable of.

And opened the door of issues in regard to voiding the warranty.
 

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The second catayltic will cost over 800.00 So I would pass on removing it. I do however don't think I noticed an o2 sensor after the second cat. So the computer would have no way of knowing if it was missing. Though not recommended..

What did the the guy with the turbo insight do with the cats?

If your serious about improving the exhaust. The best way is to have the whole exhaust system ceramic coated. This will lower engine bay temps, protect the exhaust from rust, and improve the exhaust gas flow.
The first cat is right near the engine and it heats up to over 400, real quick.
I'm goining to use Thermo-Tec header wrap on the first cat as soon as summer weather moves in to keep the heat away from the engine. But for now I think the heat will be OK in the winter weather.
 

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The second Cat is a special NOx absorbing one. It was specially designed in order to allow the Insight to opperate in lean burn mode and not emit any excessive NOx emissions. This converter runs to the tune of $1230 list price. There is a sensor at the end of this, the laf I believe that senses when the converter is saturated and knocks the engine out of lean burn to do a nox purge. So it's not just a regular easily replacable cat. I have put high flow cats on my previous vehicles, but they did not have the complexity of an Insight's ULEV system. It is still illegal to remove a working catylitic converter.

Willie still runs both cats on his turbo charged insight. If anything you might try removing the muffler and see what that does. I'm sure they have the back pressure on the system to precisely engineered though that that would probably mess something up.
 

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The Primary (Wide-band) O2 sensor is located just before the primary(first) cat. The Second O2 sensor (a normal 3 wire type) is located just after the primary cat. According to the manual and my observations, there is no sensor after the secondary cat. You could probably replace it with a straight pipe without generating a check engine light. Removing it will not stop NOX purges from occuring. It is also illegeal and will earn you the scorn of most insight owners who like their cars to be clean.

Something I have to point out is in normal cruising (2500RPM, part throttle), the amount of exhaust exiting the engine is pretty damn small. You look underneath and see 2 cats and narrows pipes and think it is bad, but there is probably less backpressure than a 3in pipe on a 5 liter V8. Now if start talking about WOT at +5000 RPM, there might be room for improvement.
 

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Discussion Starter #9
Thanks All!

Thank you for the information, everyeone! :) The InsightCentral community gets two thumbs up from me for having such knowledgable members. I wouldn't have guessed that the second cat would be a special NOX absorbing cat. I hope to join the community real soon, as soon as the dealership around my area can get a '04 Insight. :p Thanks again for the info!
 

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No NOX cat on my '00 Insight

Yes you can remove the NOX cat on the '00 Insight without generating an ECM code. Driveability is unchanged. This has been the case on my car for thousands of miles. Fuel economy has been steadily increasing as well, though I'm not certain this 6 lb. removal is the main reason.

On later Insight models there is an ECM sensor on the NOX cat, so this can not be done with the same result.

If anybody is interested in purchasing my NOX converter for a real good price, then let me know. I have it in the garage at my home in TX, and have no real use for it at this time.

-Mitch
 

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Mitch, Have you had your car emission tested without the second cat?

Did you just cut the cat off or unbolt the the cat and fab up a new pipe?
 

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Does it still lean burn without the NOX cat? I thought it wouldn't do let any lean NOX through, basically stay in a constant NOX purge mode.
 

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NOX cat removed

Cakley,

There is no emissions test in the state of Florida. There used to be one a few years ago, but if I recall correctly, only hydrocarbons and CO were accounted for. Even if NOX were tested for in a state that does such testing, I'd imagine that the Insight would still pass.

Everything from behind the catalytic converter was cut off the car. The exhaust resonator was re-welded in the position of the NOX cat, with 2.25" pipe entering and exiting, and going to a 17" stainless steel Supertrapp muffler, which is mounted under the center of the car, right above the aluminum pan.

Rick,

Yes the car still has lean burn in the same way. The ECM on the '00 Insight has no way of knowing the NOX converter is no longer there, as there is no sensor going to it, as is the case with the newer Insights.
 

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Mitch;
I have a 2001 and there is NO SENSOR located on the second cat. Don't know about 02 or 03 Insights. There would be no reason to have a sensor on that cat as it is the absorvative type. In my opinion, the exaust pipe size you used is too big in diameter and will probably cancel the scaveging effect of the exaust system.
 

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NOX cat sensor

Someone with an '02 model mentioned on the other Insight forum a while back that their service manual showed a sensor for the NOX cat on their model year. I've never verified this.

I chose the bigger exhaust pipe diameter size a couple of years ago, because I was planning on getting a turbo done within a year after the exhaust system change. It didn't happen for financial reasons, but it will happen in the future.
I only use 8 caps for the Supertrapp, which is the minimum number they recommend. Thus I still have control over the back pressure. I can increase the number of caps once a turbo is on. I expect that the noise reduction from the turbo would offset the increased noise from the extra caps in place.
 

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I could be wrong, but I sware I saw a sensor at the rear end of the nox converter on my 02. I'll see if I can look again tomorrow.
 

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Hey Rick, did you ever check?

My '01 doesn't have a sensor on the secondary cat. I'm thinking about taking it off.
 

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Fair enough, I did say I was going to check, guess I foregot. Anyways...


If thats not a sensor at the end of the NOX converter I don't know what it is. My best guess is that senses when too many NOX are getting past the converter and knocks it back down to rich to purge it. On mine it takes a long time of staying in lean burn to get a NOX purge and it will only last a few seconds usually.

Looking at Majestic Honda's page it's too small to see for sure, but the diagram looks the same, however, comparing 2000 to 2002 the list price on the nox converter is about $200 more for mine so something is different.
 

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Rick;
Check and see if you have two O2 sensors on the first cat. Also is it a four wire or a two wire sensor?
Maybe they relocated the sensor to the second cat after 2001 to give it a more complete reading.
 

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Ok, I guess we've found another difference umong the model years to add to the list. On the primary tri way cat there are two sensors. One before the catylist that would read exhaust directly out of the engine, and one after the catylist. Both are 4 wire sensors.

So the question, do I have an extra sensor then over earlier cars?
 
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