Emissions
01-19-11, 12:08 PM
#1
Junior Member
Thread Starter
Join Date: Jan 2011
Location: New London, CT
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Emissions
Just bought an 89 GXL NA out of state and took it in for CT emissions to get it registered. Back where it was, it didn't have to pass emissions and so the previous owned had put in straight pipes and done some other mods. It also has no OMP and runs premix.
So the first of what may be many questions: if I were to buy and reinstall the stock cat, does anyone know what kind of emissions reductions I might see? Right now the actual (measured)/limits on emissions were:
1122/385 PPM HC
7.07/1.23 % CO
12036/2692 PPM NOx
Guy at the counter claimed he had never seen a car fail so miserably.
Basically, I'm waiting on a list from the seller of some of the mods he had done, and it's a bit cold outside for me to spend a lot of time poking around under it to try and figure it out for myself. I'm hoping installing a cat/air pump will be sufficient to get me through emissions, but figured I'd see if anyone might know whether those on their own are sufficient enough to get those numbers down within the limits.
I've also read mixed opinions around on whether premix increases or decreases emissions, and some discussion on whether synthetic or non-synthetic two stroke is best, or whether I should run without premix for emissions. So, while it may seem counterproductive to ask for opinions again here when I've already seen some discussion with no definitive answer, it couldn't hurt to ask. Thoughts?
So the first of what may be many questions: if I were to buy and reinstall the stock cat, does anyone know what kind of emissions reductions I might see? Right now the actual (measured)/limits on emissions were:
1122/385 PPM HC
7.07/1.23 % CO
12036/2692 PPM NOx
Guy at the counter claimed he had never seen a car fail so miserably.
Basically, I'm waiting on a list from the seller of some of the mods he had done, and it's a bit cold outside for me to spend a lot of time poking around under it to try and figure it out for myself. I'm hoping installing a cat/air pump will be sufficient to get me through emissions, but figured I'd see if anyone might know whether those on their own are sufficient enough to get those numbers down within the limits.
I've also read mixed opinions around on whether premix increases or decreases emissions, and some discussion on whether synthetic or non-synthetic two stroke is best, or whether I should run without premix for emissions. So, while it may seem counterproductive to ask for opinions again here when I've already seen some discussion with no definitive answer, it couldn't hurt to ask. Thoughts?
01-19-11, 02:35 PM
#2
Well of course it failed miserably without a cat or an air pump. Those cut-offs you listed should be easily within reach if you put everything back. Are those idle measurements, or were they at speed?
CA tests for HC, CO and NOx at 2 speeds. These are the maximums from my 2009 test:
15 mph: HC: 121 ppm, CO: 0.76%, NOx: 807 ppm
25 mph: HC: 96 ppm, CO: 0.65%, NOx: 746 ppm
My 2009 test results:
15 mph: HC: 5 ppm, CO: 0.03%, NOx: 43 ppm
25 mph: HC: 27 ppm, CO: 0.03%, NOx: 26 ppm
Premix doesn't matter unless you're putting WAY too much in.
CA tests for HC, CO and NOx at 2 speeds. These are the maximums from my 2009 test:
15 mph: HC: 121 ppm, CO: 0.76%, NOx: 807 ppm
25 mph: HC: 96 ppm, CO: 0.65%, NOx: 746 ppm
My 2009 test results:
15 mph: HC: 5 ppm, CO: 0.03%, NOx: 43 ppm
25 mph: HC: 27 ppm, CO: 0.03%, NOx: 26 ppm
Premix doesn't matter unless you're putting WAY too much in.
01-19-11, 02:36 PM
#3
Unfortunately, there's no way to be %100 sure that putting an air pump and Cat on the car will be enough to limp it through emissions. Especially when you aren't even sure whats been done to the car. But start with putting some emissions stuff back on, and trying again.
I'll have to add this to my list of reasons why removing emissions equipment can be more of a hassle than it's worth, (on a stock motor) the next person to own your car may need that stuff...
I'll have to add this to my list of reasons why removing emissions equipment can be more of a hassle than it's worth, (on a stock motor) the next person to own your car may need that stuff...
01-19-11, 03:17 PM
#4
Junior Member
Thread Starter
Join Date: Jan 2011
Location: New London, CT
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Yea, I didn't expect it to pass emissions without the cat on, but I'm only given 10 days to register on a temporary tag before I have to go through all the paperwork and fees again, and am allowed to register/drive on a fail, which nets me 60 days to actually fix the problem. So, had to be tested regardless.
In response to the speed question, the car was put on a dyno and taken to 2182 RPM, whatever that works out to. It's new to me, so can't tell you straight off what that is yet.
Just being new to the world of the rotary, figured I'd ask to see if there were perhaps some other things I should check out, or whether the cat is the bulk of the emissions control. The guy at the counter seemed suspicious that a cat would bring all those numbers in range, in fact, he didn't think it would change much of anything other than the NOx, so figured I'd get the opinion of some people a little more knowledgeable about the Rex specifically, before rereading the Haynes manual over and over, becoming frustrated, and paying the shop $120 to diagnose it for me.
Appreciate all the help. Looks like I'll just start with a cat and retest, unless I get the list back from the seller and find something noticeable.
In response to the speed question, the car was put on a dyno and taken to 2182 RPM, whatever that works out to. It's new to me, so can't tell you straight off what that is yet.
Just being new to the world of the rotary, figured I'd ask to see if there were perhaps some other things I should check out, or whether the cat is the bulk of the emissions control. The guy at the counter seemed suspicious that a cat would bring all those numbers in range, in fact, he didn't think it would change much of anything other than the NOx, so figured I'd get the opinion of some people a little more knowledgeable about the Rex specifically, before rereading the Haynes manual over and over, becoming frustrated, and paying the shop $120 to diagnose it for me.
Appreciate all the help. Looks like I'll just start with a cat and retest, unless I get the list back from the seller and find something noticeable.
01-19-11, 05:47 PM
#5
The guy at the counter is rarely to be trusted. Modern catalytic converters are of the 3-way variety, which means they catalyze 3 different reactions:
1) Reduction of NOx to nitrogen and oxygen
2) Oxidation of carbon monoxide to carbon dioxide
3) Oxidation of hydrocarbons to carbon dioxide and water
Thus you will lower NOx, CO and HC levels with a cat. The oxygen supplied by the air pump is used for reactions 2 and 3.
1) Reduction of NOx to nitrogen and oxygen
2) Oxidation of carbon monoxide to carbon dioxide
3) Oxidation of hydrocarbons to carbon dioxide and water
Thus you will lower NOx, CO and HC levels with a cat. The oxygen supplied by the air pump is used for reactions 2 and 3.
Trending Topics
01-20-11, 12:56 AM
#8
Too old for this
The guy at the counter is rarely to be trusted. Modern catalytic converters are of the 3-way variety, which means they catalyze 3 different reactions:
1) Reduction of NOx to nitrogen and oxygen
2) Oxidation of carbon monoxide to carbon dioxide
3) Oxidation of hydrocarbons to carbon dioxide and water
Thus you will lower NOx, CO and HC levels with a cat. The oxygen supplied by the air pump is used for reactions 2 and 3.
1) Reduction of NOx to nitrogen and oxygen
2) Oxidation of carbon monoxide to carbon dioxide
3) Oxidation of hydrocarbons to carbon dioxide and water
Thus you will lower NOx, CO and HC levels with a cat. The oxygen supplied by the air pump is used for reactions 2 and 3.
01-20-11, 03:07 AM
#9
Senior Member
iTrader: (12)
Join Date: Nov 2010
Location: Modesto, Ca
Posts: 321
Likes: 0
Received 0 Likes
on
0 Posts
Its not that easy to install a cat the wrong direction in you car Because of the split air pipe that goes in to the cat, it can only be put in one way. Thats is, of course, a) it is not a universal flow cat b) its not a cat bought and later added a split air pipe.
I can comment on how direction would affect the fuctionality of the cat, (although after reading how they work it would make sense that it have to be a certain direction) but if it is the proper cat and it is installed properly, there should be very little room to have it on so it would be flowing the wrong direction through it.
I can comment on how direction would affect the fuctionality of the cat, (although after reading how they work it would make sense that it have to be a certain direction) but if it is the proper cat and it is installed properly, there should be very little room to have it on so it would be flowing the wrong direction through it.
01-20-11, 07:31 AM
#11
Anyone whos saying premix does not affect emissions has no idea what theyre talking about. Oil is from crude oil just about everything from crude oil are hydrocarbons. Thats what the HC measurement is. Depending on the amount of oil you are or are not burning is definitely contributing to that HC number. You need to do some serious work it sounds like all the emission components have been removed. I would say start from getting the 2 oem precats, main cat with split air and air pump installed. Also please if you know your car has no cats and premix dont go get it tested though those idiots should have noticed and made it fail the pretest.
01-20-11, 12:21 PM
#13
Anyone whos saying premix does not affect emissions has no idea what theyre talking about. Oil is from crude oil just about everything from crude oil are hydrocarbons. Thats what the HC measurement is. Depending on the amount of oil you are or are not burning is definitely contributing to that HC number.
01-20-11, 01:39 PM
#15
https://www.rx7club.com/showpost.php...4&postcount=26
Just to clarify, a converter doesn't burn anything. Our pollutants react on the surface of a catalyst. Catalytic agents are used so the reaction takes place at a far cooler temperature than that reaction would take place in the natural state(burning).
The engine produces the following pollutants that the catalytic converter treats:
Nitrates/nitrites of oxygen-NOx,
Unburned hydrocarbons-HC
Carbon Monoxide-CO
The front brick contains rhodium. This is the reduction catalyst. It converts nitrates of oxygen into pure Nitrogen and pure Oxygen.
2NOx → N2 +O2
In chemistry, this is called a reduction reaction, because it reduces or removes one or more oxygen atom from the compound (simplified!)
The back brick contains Palladium. This is the oxidation catalyst. It converts unburned Hydrocarbons and Carbon monoxide into Carbon dioxide and Water as follows:
2CxHy + (x+y)O2 → 2xCO2 + yH2O
2CO + O2 → 2CO2
This is called a oxidation reaction because it adds one or more Oxygen atom to the compound(s). (again, simplified)
Platinum may or may not be added to both oxidation and reduction bricks to enhance/tweak the reaction.
Where does the back brick get the extra Oxygen for the back brick to use? 2 places. Under some conditions, the front brick combines enough free O2 to sufficiently oxidize the unburnt HC and the CO. Under other conditions, the oxygen combined in the front brick is insufficient, so the air is pumped into the converter via the air tube in the middle. The engineers can sufficiently predict the engine states so as to provide controls to apply the correct amount of air into the correct place in the system, based on the rpm, engine load, throttle position etc. This is the control system that Hailers describes so nicely.
By their nature, rotaries are not terrible NOx offenders, as AGreen says.
Once we got piston engines to OBDII, most cars dropped the air tube to the 3-way converter. They get by just fine with a 3-way and no air tube. The relatively clean burning piston engine produces enough NOx in the front brick to provide sufficient free O2 to oxidize the (relatively low) unburned HC's in the back brick.
If you do not believe my explanation, look it up.
Class dismissed.
This is the way a 3way catalyst with air tube works in our rx7
The converter has two catalyst bricks, one in the front half and one in the back half. The air tube injects air evenly distributed into the open space between.The engine produces the following pollutants that the catalytic converter treats:
Nitrates/nitrites of oxygen-NOx,
Unburned hydrocarbons-HC
Carbon Monoxide-CO
The front brick contains rhodium. This is the reduction catalyst. It converts nitrates of oxygen into pure Nitrogen and pure Oxygen.
2NOx → N2 +O2
In chemistry, this is called a reduction reaction, because it reduces or removes one or more oxygen atom from the compound (simplified!)
The back brick contains Palladium. This is the oxidation catalyst. It converts unburned Hydrocarbons and Carbon monoxide into Carbon dioxide and Water as follows:
2CxHy + (x+y)O2 → 2xCO2 + yH2O
2CO + O2 → 2CO2
This is called a oxidation reaction because it adds one or more Oxygen atom to the compound(s). (again, simplified)
Platinum may or may not be added to both oxidation and reduction bricks to enhance/tweak the reaction.
Where does the back brick get the extra Oxygen for the back brick to use? 2 places. Under some conditions, the front brick combines enough free O2 to sufficiently oxidize the unburnt HC and the CO. Under other conditions, the oxygen combined in the front brick is insufficient, so the air is pumped into the converter via the air tube in the middle. The engineers can sufficiently predict the engine states so as to provide controls to apply the correct amount of air into the correct place in the system, based on the rpm, engine load, throttle position etc. This is the control system that Hailers describes so nicely.
By their nature, rotaries are not terrible NOx offenders, as AGreen says.
Once we got piston engines to OBDII, most cars dropped the air tube to the 3-way converter. They get by just fine with a 3-way and no air tube. The relatively clean burning piston engine produces enough NOx in the front brick to provide sufficient free O2 to oxidize the (relatively low) unburned HC's in the back brick.
If you do not believe my explanation, look it up.
Class dismissed.
01-20-11, 01:50 PM
#16
Rotary Freak
Most of the aftermarket converters I've bought, have what is technically called the Big *** Arrow embossed in the outer cover showing the flow direction of the gasses i.e. towards tail pipe from the engine exhaust ports.
You won't have any trouble installing it in the right direction............even if you blind your fingers can read the embossed arrow....humor
You won't have any trouble installing it in the right direction............even if you blind your fingers can read the embossed arrow....humor
01-20-11, 02:52 PM
#17
I'll second what hailers mentioned. The magnaflow cat with an air pipe I bought, had a big flow arrow on it. Unfortunately, because I wanted the heatshield on the top, this meant I had to cut and re-direction the air pipe tube. Not a big deal, but it added to the overall project.
01-20-11, 09:40 PM
#19
Junior Member
Thread Starter
Join Date: Jan 2011
Location: New London, CT
Posts: 35
Likes: 0
Received 0 Likes
on
0 Posts
Well, to answer MazdaMike, I wouldn't have gotten it tested if I had a choice. I live in a too small town with too much crime and too many cops, and they tend to notice pesky things like driving without a license plate. Failed test lets me register the car and put plates on it and gives me 60 days to rectify the problem.
Tuscanidream - CT does have the 25 year rule and I'm 3 years shy. Unfortunately, I don't think I have the connections to get this to slide around here. The guy at the shop didn't seem to be looking to do any favors. From what I've seen, popping some of the emissions stuff back on shouldn't be too difficult or costly, though (knock on wood).
Tuscanidream - CT does have the 25 year rule and I'm 3 years shy. Unfortunately, I don't think I have the connections to get this to slide around here. The guy at the shop didn't seem to be looking to do any favors. From what I've seen, popping some of the emissions stuff back on shouldn't be too difficult or costly, though (knock on wood).
01-21-11, 12:31 AM
#20
Too old for this
Ah. I should have worded my question slightly different as I was unsure if the different catalytic materials were segregated in the catalyst or distributed evenly throughout. Your second post answered that question perfectly. Thanks.
Thread
Thread Starter
Forum
Replies
Last Post
Snook
3rd Generation Specific (1993-2002)
17
02-27-21 02:54 PM
ls1swap
3rd Generation Specific (1993-2002)
12
10-01-15 07:58 PM
PinkRacer
2nd Generation Specific (1986-1992)
43
10-01-15 09:13 AM