UPDATE: August 3, 2006
I went back to the test station today. My objective was to see if changing the plugs would improve my HC levels. After checking that, I was going to move on to either the DE or VE ECU, or maybe the Calum VE ECU. So here are the changes I made for today:


Removed plugs (PFR6G-11) and replaced them with BKR6E-N11 gapped to 0.8mm. These plugs are OEM, copper, and have a v-groove in the insulator electrode that is visible if you look for it.
Ran a fuel mixture of 50% high test and 50% 89 octane with 10% ethanol
Timing at 13*BTDC
Fuel pressure at 40 psi -- this gives me an A/F ratio that mimics the ratio I read in the stock DE

At the inspection station, the first roller test was aborted due to sample dilution. This happened 2 more times. Three strikes and you are out in Maryland. They "downgraded" to an idle test, which I passed. Here are the idle test results:

HC Limit: 220 PPM; Test Result: 168 PPM
CO Limit: 1.20%; Test Result: 0.45%

I was happy to pass -- good for two more years! But disappointed that I was not able to learn more about how to tune for emissions reduction.

One of the reasons I switched from a cammed DE to a VE was that I was tired of fighting the emissions testing challenge every two years. So I was pretty disappointed when my car did not pass the Maryland roller test. I'm interested in suggestions on how to set the car up to pass.

My setup:

VE injectors
DE MAF
JWT ECU (this ECU was initially very lean, JWT custom tuned it for my application by richening the mixture)
Fuji, Magnaflow Hi Flow Cat, 2.5" exhaust
NISMO AFPR set at 43 psi (with vacuum hose removed)


I have tested 3 times so far, here are the results.

http://www.sr20forum.com/gallery/data/500/medium/Emission_Results.jpg


As you can see, I am failing HC. NOx can also become a problem under some circumstances. Here are the roller data tracings from my last test: http://www.sr20forum.com/gallery/showphoto.php/photo/4407/si/Roller_Data

I am considering the following possibilities:


Switch to a DE ECU, set timing to 20* BTDC. I have tried this and the car ran OK, the A/F ratio at WOT looks OK on my wide band O2 sensor -- it's close, I can tune it in to mimic the OEM DE setup at WOT with the AFPR.
Add alcohol to the fuel for the test (I'm not confident I have good information on what kind of alcohol or how much)
Add a second cat (I have an old Nissan OEM cat laying around that I could install behind the Magnaflow)
Run hotter plugs (I'm running NGK platinum 6's now -- go to 5's for the test)
Other?


What do you guys think would be both effective and safe?

Thanks.

Bill Conner

running rich. Take some fuel out. keep it at 15 degrees timming. Beat the hell out of the car to get the cat hot. Make sure the car doesnt sit before testing. try to arrange it going right on the dyno. I had the same problem with a customers car. remember they test the car on the dyno at a steady cruise of 25mph. make sure you are 14.7 to 1. air fuel. at that mile per hour. they will probably test it in 3rd gear.

I never understood why people run so much fuel pressure. Around 30psi is where I ran when I took emissions (stock VE everything) and it passed swimmingly. Granted the JWT ECU would be different, but again that's a bit of pressure.

I agree with what the cowboy said.

Dry gas, a couple bottles(2-3) of it with like 1/4 of a tank left. HC is too much timing usually, or more so that when you lower it the HC drops but your shiet is weird. As for the roller testing, I passed with a DE ecu on my VE w/ just 20 degrees timing and VE injectors and no fpr.

remember they test the car on the dyno at a steady cruise of 25mph. make sure you are 14.7 to 1. air fuel. at that mile per hour.

Thanks for the input, supercowboy, but in MD, they run at varying speeds using a standardized program. If you click on the link that I provided above, you will see vehicle speed and grams/mile for the pollutants plotted against seconds during the test. I know my car idles and cruises at a constant speed with a good A/F ratio (14.7) because I have monitored this on the Innovate wide band. It's the throttle on and throttle off action that really kills my results, though HC has to come down across the board.

Any other thoughts are welcome.

.

I never understood why people run so much fuel pressure. Around 30psi is where I ran when I took emissions (stock VE everything) and it passed swimmingly. Granted the JWT ECU would be different, but again that's a bit of pressure.

43 psi with the vacuum hose pulled and plugged is OEM spec. So I don't know why you would think this is a lot of pressure. With the hose connected, the pressure guage will show about 36 psi.

Also, note that when I pulled 5 psi off the pressure and retested, HC did not improve and NOx got worse.

It's good to hear that you passed WA State with VE ECU and VE MAF. Where did you set your base timing with the VE ECU?

Thanks for your input.

Bill

Dry gas, a couple bottles(2-3) of it with like 1/4 of a tank left. HC is too much timing usually, or more so that when you lower it the HC drops but your shiet is weird. As for the roller testing, I passed with a DE ecu on my VE w/ just 20 degrees timing and VE injectors and no fpr.

Note from the data I've posted in this thread that timing from 8*-15* BTDC has had very little effect on HC's. NOx decreases with less advance, but HCs did not change much.

It's very helpful to hear that you passed NY with the DE ECU and 20* BTDC timing at stock fuel pressure. What was the rest of your setup (header, cat, intake?). And what kind of testing do they do in NY?

I'm thinking that maybe my next try will be with DE ECU and my fuel pressure tuned in to mimic the A/F ratio that I get on my stock SR20 at WOT 3000-7000 RPM.

Then I may try the dry gas, depending on what the outcome is with the DE ECU.

I only have two weeks to get this sorted and and then they might open my hood. Not something I want to have happen!

Bill

Testing is very similar to Maryland I guess. Drive at variable speeds and maintain a speed of 55mph for like 20 sec. Its a like a course on a screen and the dot has to sway within the lines which is dictated by the speed of the car.
My setup is CAI, muffler, stock VE header VE injectors DE ecu and 20 degrees. The dry gas helps to lean it out, its what my inspector friend puts in all his customer cars if they barely failed.
As for the timing and fuel pressure, you did the reverse to lower emissions. You lowered fuel pressure and raised the timing. Think of the Civic in this case, they are designed to be emissions friendly by having lowered timing and low fuel = less power.

Make sure you put the de injectors in w/the de ecu keep the timing at 15* or so. this will lean out the mixture. Hopefully you still have the de injectors. If not let me know I have an extra set.
-Mike

fyi this is prob your last test on your OBD I car as they are for a fact going to stop testing obd I cars.

All obd I cars just need to go pass one more time and that is it.. no more emissions. There are facts all over the net, search around on google.

When is the last time you changed your oil Bill? That has made the difference in passing for me before. Also, if you get desperate try adding a 2nd cat to burn off more HC.

fyi this is prob your last test on your OBD I car as they are for a fact going to stop testing obd I cars.

That would be a fantastic development. Thanks for a ray of sunshine!

When is the last time you changed your oil Bill? That has made the difference in passing for me before. Also, if you get desperate try adding a 2nd cat to burn off more HC.

Thanks, Matt. My third test was with a fresh oil change -- it showed no real improvement in HC levels. I'm thinking that maybe the following course of action makes sense:


Test with alcohol added to the tank.
If fail, test with DE ECU, VE injectors, adjust fuel pressure to mimic stock DE A/f ratios at WOT, set timing at 20*.
If fail, add second cat.
If fail, reinstall DE.

This doesn't help your emissions issue, but what is up with the jwt ve program? Is it setup for 4bar fuel pressure? Does anyone know what the VE FPR is set to? I know of two other guys that set their nismo fpr to 3 bar and ran super lean until they raised their fuel pressure to 4bar.

deleted

Bill,

In IL we have a similar testing scenario, where the car is run on the dyno at varying speeds and loads for a test. My setup is very similar to yours, and I had my car tested just a couple days ago.

Mine:
VE inj.
DE MAF
Fuji, 3" exhaust, & 3" CarSound cat (installed 11-05)
Nismo AFPR set at stock (last time I checked)
Calum ecu that we tested in January and wasn't running lean

My:
http://www.sr20forum.com/gallery/data/500/medium/NX_Emmissions.jpg

I noticed my test was in grams and yours were gpm, but it should give you a better feel.

My question is how old is your cat? Didn't some of the Random Technology cats have issues w/ degrading rather quickly?

Josh

I intitally failed WA state emissions (setup was VE inj, DE MAF, DE ECU, fuel pressure @ stock setting, timing @ 17 degrees).

I went home and turned the timing down to about 10 degrees, and the fuel pressure to about 20psi, babied it back to the test facility and just barely passed. This was with no cat.

Fosters wrote: My question is how old is your cat? Didn't some of the Random Technology cats have issues w/ degrading rather quickly?

My cat does not have too many miles on it -- it's a Magnaflow. But who knows what it's been put through with the engine swap, tuning, tracking, etc. With high HCs and marginal NOx, more cat couldn't hurt.

Congratulations on the pass! I'm going to try adding a half gallon of denatured alcohol to a quarter tank of gas, run the timing at 13 degrees and see what happens. If that doesn't do it, I will either swap in the VE ECU with Maxima MAF or the DE ECU with DE MAF. If that doesn't get her done, I will add a second cat to my exhaust system. That's my current thinking, at least.

Thanks for checking in, Josh.

I intitally failed WA state emissions (setup was VE inj, DE MAF, DE ECU, fuel pressure @ stock setting, timing @ 17 degrees).

I went home and turned the timing down to about 10 degrees, and the fuel pressure to about 20psi, babied it back to the test facility and just barely passed. This was with no cat.

NO CAT? Now I really feel left behind! That gives me cause to hope that I can pass with DE ECU, DE MAF, 13 degrees timing, and a cat. I don't think I would feel right driving at 20 psi fuel pressure, though. Was that with the vacuum hose connected?

See update in post #1.

I would like to thank everyone who took the time to offer suggestions. It'd be real lonely facing something like this without your help.

Bill

Congrats on passing but what exactly is the sample dilution violation?? Could it detect the extra stuff you put in the tank or something??

Cheers-
Erich