BARELY failed emissions, need suggestions
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Darkside FD
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BARELY failed emissions, need suggestions
I have a very heavily modified single turbo FD. With the placement of the turbo I can't install a mechanical air pump so this is my emissions test without the airpump.
AZ does an IM-147 test which is on a dyno at varying speeds to represent real world driving. My results were this
Measured Standard
HC 0.81 0.80
*** 8.23 12.00
NOx 1.52 2.00
I know high HC could be related to ignition or a misfire so I replaced my spark plugs (now the stock 9 and 7 configuration) and changed my oil. I went back and retested thinking I would pass and HC got worse.
Second test
Measured Standard
HC 0.87 0.80
*** 5.23 12.00
NOx 1.72 2.00
Is there anything I can do to help the HC? I was thinking I may be running a little too lean and that leading to a misfire... I am not sure. I read a technical paper on this and a too lean condition could lead to higher HC. I have some cells when they were on the dyno that were in the 18:1 range, and also some cells in the 12:1 range. The problem is these are so far off of normal driving conditions that it is really difficult to tune them.
I know an electric airpump would easily fix the problem but I dont want to go and buy one to pass when I am so close without it. Any suggestions?
AZ does an IM-147 test which is on a dyno at varying speeds to represent real world driving. My results were this
Measured Standard
HC 0.81 0.80
*** 8.23 12.00
NOx 1.52 2.00
I know high HC could be related to ignition or a misfire so I replaced my spark plugs (now the stock 9 and 7 configuration) and changed my oil. I went back and retested thinking I would pass and HC got worse.
Second test
Measured Standard
HC 0.87 0.80
*** 5.23 12.00
NOx 1.72 2.00
Is there anything I can do to help the HC? I was thinking I may be running a little too lean and that leading to a misfire... I am not sure. I read a technical paper on this and a too lean condition could lead to higher HC. I have some cells when they were on the dyno that were in the 18:1 range, and also some cells in the 12:1 range. The problem is these are so far off of normal driving conditions that it is really difficult to tune them.
I know an electric airpump would easily fix the problem but I dont want to go and buy one to pass when I am so close without it. Any suggestions?
#3
Racecar - Formula 2000
What cat are you using? Did you run the car long enough to get the cat good and hot before the test?
Dave
Dave
#5
Darkside FD
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With an electric air pump I know i would pass. I drove around for probably 20 minutes to get the car warm. I am using a Magnaflow cat right now that has the air pump attachment but I have it plugged. It has seen MAYBE 10,000 miles of use over the two years I have had it. I really doubt even that much...
I think it is all in the way the guy drives the car on the rollers. The last guy was totally erratic. Full throttle, then totally lugging the engine. The first guy stalled the car twice trying to do the test. IF I could drive the car, it would pass. I was just wondering if anyone knew of any tricks to lower HC?
I used some alcohol in the second test, I was just wondering if using alcohol helped with HC or the other gases? Using alcohol seemed to lean my car out further though, so maybe it was a source of my problems in the second test...
I think it is all in the way the guy drives the car on the rollers. The last guy was totally erratic. Full throttle, then totally lugging the engine. The first guy stalled the car twice trying to do the test. IF I could drive the car, it would pass. I was just wondering if anyone knew of any tricks to lower HC?
I used some alcohol in the second test, I was just wondering if using alcohol helped with HC or the other gases? Using alcohol seemed to lean my car out further though, so maybe it was a source of my problems in the second test...
#6
Racecar - Formula 2000
Are you still using the ACV?
Dave
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Alcohol makes the car run leaner and helps with HC which is unburnt fuel at the expense of increasing nox. Hotter spark plugs often also help
Many other cars including I believe LSX based GM's come with electric air pumps it should be cheap and easy to find one.
first one found in search: http://cgi.ebay.com/ebaymotors/00-04...spagenameZWD1V
Many other cars including I believe LSX based GM's come with electric air pumps it should be cheap and easy to find one.
first one found in search: http://cgi.ebay.com/ebaymotors/00-04...spagenameZWD1V
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Racecar - Formula 2000
Dave
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I am going to tune the map to run 15:1 or so on the alcohol mixture. I had the map tuned nicely for regular gasoline, put the alcohol in and all of the sudden I am two points leaner on my wideband. I think that is what hurt me. Maybe I should try it with the new plugs on straight gasoline?
If I was way off I would for sure be buying an electric air pump and rigging it up, but I dont want to go through the hassle if I can fix it with something cheap and easier...
If I was way off I would for sure be buying an electric air pump and rigging it up, but I dont want to go through the hassle if I can fix it with something cheap and easier...
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This may be part of the problem. My car runs at 83 degrees C all the time now that I have no intercooler. I have the stock thermostat.. Maybe I should unplug the fans and let it sit till it gets up in the 90s C and then do the test. I heard that when the flame front hits the cooler walls of the chamber it produces more HC emissions...when the walls of the chamber are hotter it lessens the HC emissions which is probably why Mazda made these cars run so hot.
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#19
"Elusive, not deceptive!”
You are so close.
Going from rich to lean, HC and CO are decreasing while NO is increasing. The best compromise is at stoich 14.7AFR.
Your use of the hotter (7's and 9's) sparkplugs to keep engine miss to a minimum is a good idea also.
It sounds like you have to smooth the AFR's in the test range better (12-19AFR's is probably killing you).
What timing and split are you using in that range?
Barry
Going from rich to lean, HC and CO are decreasing while NO is increasing. The best compromise is at stoich 14.7AFR.
Your use of the hotter (7's and 9's) sparkplugs to keep engine miss to a minimum is a good idea also.
It sounds like you have to smooth the AFR's in the test range better (12-19AFR's is probably killing you).
What timing and split are you using in that range?
Barry
Last edited by Barry Bordes; 01-03-08 at 09:44 PM.
#21
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With an electric air pump I know i would pass. I drove around for probably 20 minutes to get the car warm. I am using a Magnaflow cat right now that has the air pump attachment but I have it plugged. It has seen MAYBE 10,000 miles of use over the two years I have had it. I really doubt even that much...
I think it is all in the way the guy drives the car on the rollers. The last guy was totally erratic. Full throttle, then totally lugging the engine. The first guy stalled the car twice trying to do the test. IF I could drive the car, it would pass. I was just wondering if anyone knew of any tricks to lower HC?
I used some alcohol in the second test, I was just wondering if using alcohol helped with HC or the other gases? Using alcohol seemed to lean my car out further though, so maybe it was a source of my problems in the second test...
I think it is all in the way the guy drives the car on the rollers. The last guy was totally erratic. Full throttle, then totally lugging the engine. The first guy stalled the car twice trying to do the test. IF I could drive the car, it would pass. I was just wondering if anyone knew of any tricks to lower HC?
I used some alcohol in the second test, I was just wondering if using alcohol helped with HC or the other gases? Using alcohol seemed to lean my car out further though, so maybe it was a source of my problems in the second test...
I have definitely seen they are more likely to let you drive the car if it is manual. Not sure if yours is manual or automatic.
I don't know if you live in Phoenix or Tucson, but when I bought my FD (manual) in September I took mine to the emissions on Valencia & I-19 and I was the one who drove it during the test.
If yours is manual and live in Tucson, maybe try taking to that emissions location?
#22
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I'm due for emissions soon (on my second extension..) I'll give it a chance to pass as is (stainless cat and no pump) but when it fails, I think my plan is:
- Uber lean tune. Won't fail you for NOx on a 93.
- disconnecting the charge pipe and run N/A
- borrow stock cat
- plumb some of the charge into the cat air pipe. Since I don't have an air pump this would be the easiest way to get air into the cat without electric BS.
Good luck.
- Uber lean tune. Won't fail you for NOx on a 93.
- disconnecting the charge pipe and run N/A
- borrow stock cat
- plumb some of the charge into the cat air pipe. Since I don't have an air pump this would be the easiest way to get air into the cat without electric BS.
Good luck.
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