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Old 10-30-2007, 06:11 PM   #1
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Default Another emissions failure

Here's what I did:

Took 6 off the base timing map of the MSPNP 90-93.
Tuned for AFR of 15.0 in the appropriate zones for the test (~1500-3000rpm, <= 50kPa).

Barely passed the 25/25 test

HC CO NOx
read 149 0.9 1046
allow 160 0.9 1179

Failed the 50/15 test

HC CO NOx
read 196 1.46 1135
allow 166 0.93 1304

I don't want to reduce timing any more than it is, for fear of busting over the NOx limit.

Clearly, I'm running rich (indicated by high HC AND CO) but there could be other problems. Maybe my wideband reads leaner than true?

Anyway, I pretty much have to get this to pass by the weekend. Any ideas besides leaning out the load zones and trying again?
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Old 10-30-2007, 06:13 PM   #2
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Try a different wideband
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Old 10-30-2007, 06:15 PM   #3
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Ha, I wish I had the time (and $) for that
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Old 10-30-2007, 06:19 PM   #4
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bens? What about the fellas at DIY?
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Old 10-30-2007, 06:24 PM   #5
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You datalogged the emissions test dyno run right??

There's an emissions dyno w/ a 5GA in lawrenceville. I think they'll let you run for $40, but you'll either need to make an appointment or show up early and wait.
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Old 10-30-2007, 07:45 PM   #6
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Quote:
Originally Posted by Ben View Post
You datalogged the emissions test dyno run right??
Yup. There was a bit of an issue because my AFR target rpm bins were at 1000 and 2000, and 1000 was set for idle ~13.8. the 50/15 test rpm was right around 1900, so I blipped down into cells that were tuned at interpolated points between 13.8 and 15.0. I tweaked the rpm bins to make sure the test rpms were in cells tuned for 15.0. Retuned, and actually had quite a few VE cells change. Went back to the emissions place, cause the operator said if I made it back before 6 with some tweaks he'd let me run a "training session" to see where I stood before taking my free retest. Well, when I got back, he and some other workers were pretty into the car, and told me "oh, it'll pass." I passed with flying colors, and I won't ask any questions. But I think I'll hit the ATM tomorrow, go back and submit to the "Tips are Appreciated" sign.
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Old 10-30-2007, 08:22 PM   #7
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Quote:
Originally Posted by Atlanta93LE View Post
I don't want to reduce timing any more than it is, for fear of busting over the NOx limit.
My understanding was that advanced timing increases the NOx, retarding it increases the CO.
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Old 10-30-2007, 09:12 PM   #8
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It's a small pic, but I'm not going to pay for a subscription to "Dieselnet." It has less of an effect than I thought, but you can see that NOx increases with decreased timing.

On another note, I'm pretty sure my cat wasn't fully warmed up either. NOx shouldn't have been that high, and I didn't drive it too quickly before testing. I should have taken it on the freeway for a bit. Oh well, "passed" now.

More info:
"Ignition-Advanced ignition timing will raise HC emissions at idle speed and under light load. Retarding the spark will lower HC and, in many instances, the level of NOx, even if detonation is not present. Ignition timing has no direct effect on CO but can impact it by changing the rpm of the engine and the amount of throttle angle needed to maintain idle speed. A high-energy aftermarket ignition system allows the spark plug to burn for more of the crankshafts rotation, cleaning up the level of HC. Multiple-strike systems also have a positive impact on HC production. Spark-advance curve tuning, by means of adjustable vacuum-advance units and spring kits, is essential for any drive-cycle testing."
See this article for a thorough look at emissions and things related.
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Old 10-30-2007, 11:02 PM   #9
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Nice
I don't like coming back with cash; I usually will come back with beer and/or lunch.
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Old 10-30-2007, 11:10 PM   #10
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Nice
I don't like coming back with cash; I usually will come back with beer and/or lunch.
Yeah, I thought about beer and lunch...but don't know what a safe kind to bring is. Case of bud is safe, yeah?
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Old 10-30-2007, 11:32 PM   #11
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Yeah, any of the standard CDB's should be fine.
CDB = cheap domestic beer
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