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?

 

Add Alcohol to fuel and change map to compensate.

Rig an air bottle with a line to the cat, lol. Don't do it.

Add pass emission additive to fuel.

 

What cat are you using? Did you run the car long enough to get the cat good and hot before the test?

Dave

 

fwiw, rx8 uses an electric air pump iirc

 

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...

 

The 2nd test results did look like the result of a slightly leaner mixture (higher NOX & HC), so maybe w/o the alcohol it MIGHT be better.

Are you still using the ACV?

Dave

 

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

 

The reason I said that higher HC might indicate leaner, is that too lean causes misfires, raising HC's. I should have explained that better...

Dave

 

Move to somewere theres no emissions

 

You mean the flyover states?

 

put in a higher temp thermostat and lower your boost levels, hotter engine running temps lead to an overall decrease in hydrocarbon emissions.

 

i dont know wat you mean by "flyover" states but i know florida has no emissions and some random countys throughout the U.S.

 

Louisiana has NO emissions testing

 

put a quart or two of denatured alcohol in the tank and drive around for a bit... thats what i did, cleared things right up, car ran like butt until it burned it all out.

 

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...

 

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.

 

Maybe also do a water steam clean to your engine to remove unburned deposits in the engine. Just a though.

 

How do you do this without hydrolock?

I have water injection...and the engine is only about 6K miles out of a fresh rebuild.

 

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

 

Nevermind, if you got water injection the motor is already steam cleaned.

 

They don't seem to have a formula for who drives it b/c I have taken many cars, both automatic & manual and sometimes they insist on driving it and sometimes they let me do it. It probably depends on the person at the emissions doing your car at that time.

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?

 

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.