emission test yesterday - the results - need your input
 

I had my car emission tested yesterday (Washington state) and failed the cruise emissions 25 mph test for HC (PPM) AND CO (%). I passed the idle test for HC and CO. The results are in the attached spreadsheet. When I spoke to the site manager, she explained that the HC number indicated a lean condition and the CO number indicated a rich condition for the cruise emissions results. Not really clear on how the car can be running both lean and rich at the same time. Her opinion was that there was a problem beyond a simple A/F adjustment.

I rebuilt the engine (small street port) last winter and spring and it runs very well other than a slight idle pulsing. The idle A/F is set for ~14.7 AFR and at 2000 RPM it runs ~12.5 AFR. Initially, when I first started the rebuild prior to setting fuel levels, the main cat got very hot (glowing red) a few times until I tweaked the A/F.

The oil was changed 2 days ago and I plan on changing the plugs as well. I will be checking the air pump function, the ACV, and the CAT and I will throw in a gallon of denatured alcohol for the followup test.

Would appreciate input regarding the results in the attached spreadsheet. Are there target AFR's for the 2 load levels that would bring my numbers into the required range? Can specific components be at fault and attributable to creating these failed readings?

Thanks for explaining what the numbers mean and any feedback, suggestions, or advise you may have.

-chuck

If you have the PFC, you need to run the 25 mph test in 3rd gear, not 2nd. 2nd puts the rpms above 2500 rpm and the air pump is cut off (instead of 3200 rpm like the stock ecu).

She is probably interpreting excess HC as a lean miss which would definitely produce excess HC. It is slightly possible that if you have some fuel supply problem, one rotor running too lean and missing, and one running rich. However, I think that, as rynberg says, they are both a result of no air-pump supply to the cat, not allowing the cat to burn the HC's and CO.

Dave

some where on here? didnt j-rat post somthing about beating emissions test running car on alcahol

HC are untouched fuel. CO are partially burned fuel. Could also be a timing issue.

Thanks for the info. With that in mind, I am going to take out a little insurance by wiring the pump to on all the time. I had a hard time stabilizing the rpms and as I recall the tach did fluctuate between 2000 and 2500 rpms. The rollers made the car feel like I had an out of balance or out of round tire.

I havent done a visual inspection of the cat, but based on the test results, is there any possibility that it could be a contributing factor to the failed tests?

-chuck

What timing settings will help reduce emissions - a little advanced or a little retarded and by how much?

I've heard anywhere from 5:1 to 1:1 Gasoline to Denatured Alcohol

Be careful, running it all the time will burn it out. Only rig it for the test.

I was going to add 1 gal to a quarter tank of gas for the test only and then top it off afterwards with premium.

Possibly, but I don't think you would have passed at idle if it were really bad. However, a partially failed (partially-coated catalyst) cat would have more trouble burning the HC's and CO as flow increased with increased RPM, since the residence time of the gasses would be shorter.

However, I still think it was more likely to have been an air pump issue.

Dave

Thanks Dave!

AFRs of 12.5 at 2000 RPM in vacuum are way to rich. Do you have any fuel mods?

The air pump on these car does a good job of diluting the exhaust gasses so wiring the pump to run continuously may work, but be carefull to keep the revs down, I don't think the air pump can take a run to redline.

Car has: downpipe, RB catback, I built a custom made carbon fiber cold air intake which funnels air from the "mouth" of the car into the bottom of the stock airbox which has a K&N filter. Fuel is controlled with PFS.

I adjusted the AFR to ~14.5 up to about 4000 rpm for now and will be trying the test again tomorrow.

thanks for info
-chuck

Let me know how that goes Chuck. I am thinking about tuning my PFC and possibly a little Alcohol to pass emissions with my FD. I passed at Cruise and failed miserably at Idle without an airpump.

Search for posts from "Wargasm" he has threads on here telling you exactly how to pass and what ratio to run.

I went in yesterday for the test and this time passed the 25mph test and failed the idle test. The car at the end of the test started to die at idle and I noticed that the wide band was showing the afr's going slightly rich. Looks like I will have to go in one more time. I am thinking that my cat may not be operating at 100%.

Back to the drawing board. Again, thanks to all for your input.

-chuck

Hey Chuck, how many miles on your cat? I have a spare one in my garage that you can use if yours has higher mileage. I'm not sure what condition the interior of the cat is in but I didn't have any problems with it.

Ive got 53,000 miles on mine but as I mentioned earlier, it got red hot a few times when first starting my rebuilt engine. If you get a chance, perhaps you can do a visual on it and let me know how it looks. Ive got to get my tabs by Jan 31.

Thanks Tim!

-chuck

Hey Chuck. I think your car is an auto trans like mine right? . for the auto trans you need to run the test from 0-15 mph in first gear then shift to second gear from 15-25 mph . leave it in second gear for the rest of the test. if the tech lets it go into overdrive it will run pig rich and fail. mine passed just fine after being tested like this.

Jeff

http://71.102.125.165/rx7/emissions.htm

My emissions info there... it's for MD, but the testing procedures are fairly similar.

If you're running 12.5:1 at ~2000 RPM - that will make your cat (if equipped) work hard to clean that exhaust up. I'm not sure that you CAN pass with a 12.5 even with a cat.

Assuming that you are running a decent-condition main cat, and a working air pump, changing your mixture to closer to 14.0-15.0 :1 everywhere in the test zone should work. Different widebands read a little differently (I have seen up to 0.5 to almost 1.0 full point on my car with simultaneous readings from two different wideband brands), so 15:1 on my car might be 14.5:1 on yours... or maybe 15.5:1 or whatever. The point is to make it run pretty lean but still pretty smooth. If you lean it out to the point that it starts stumbling, you will fail (and it probably isn't good for your car). Sounds like your car runs nicely at 14.7:1 on your wideband, so I'd shoot for that. Set the range from full-vacuum up to 0 boost like this and also 0-4000 rpm. Everywhere else, leave like it is now! If you accidentally go into boost, you don't wanna blow your engine with some lean map. So basically you end up with "Mr Clean" car under the conditions of sub-4000 RPM and no boosting. Anywhere else, and the car will run normally. Gotta drive CALMLY when you're on this map - like a granny.

Anyhow, take this advice at your own risk, tuning your car IS dangerous! Alcohol helps too. I use 1 gal denatured alc in 1/4 tank of the best gas you can find... around here in Seattle that seems to be shitty 92 octane. I miss my Maryland 94 octane!

Wargasm, are the AFR numbers you are quoting measured when the airpump is connected? I seem to have pretty inconsistent readings when the airpump is connected, although that may be a symptom of a bad ACV. Any body know of a definitive test for the ACV? I just put a different one on and I have yet to check whether there is any air coming out of the air tube to the cat now.

Hey Chuck I'll check it after work this evening and see how it looks, the car had about 90k miles on it when it was removed not sure how many on the cat, but like I said I never had issues...

Ok Chuck, it looks pretty good inside the cat as far as I can see. The screen has a little debris on it but nothing more than I would expect. I'd be open to bringing it to you if you want to check it out. I pm'ed you my cell #.

Nice write-up! Thanks for the info. Im going to try it again tomorrow as I believe I have implemented all of the changes needed to pull this thing off now. Im going to lean it out a little bit more 0-4000 and go for 15-15.5 afr.

What killed my idle test last time was at the end of the test when my car started to die. I watched my afrs go to ~11.5-12.5 and I had a feeling that it was probably going to fail.

Im glad that their personnel dont drive our vehicles. They saw my computer and wide band setup and said nothing. One of the guys that worked there said before I started that they should give sports cars with turbos like the RX7 and Celica Supra waivers because of the what the cars were designed for - lots of power and to go fast. Unfortunately, he wasnt the one that tested my car.

Jeff, I am going to run it in Hold mode in second for the 25mph test. I did notice that my afrs were better at their designated testing speed. At idle when in gear my afrs were more consistent and stable while holding the idle speed at 800-850 rpm.

thanks again for all the info.

-chuck