Emissions testing

[vanpraag]

Went to the emissions testing station this morning and failed the Hydrocarbon test. Reading was 2138 ppm, 4 times the max limit. The Carbon monoxide was .5 max 5.00. Question is, what is causing a high hydrocarbon reading??? I'm thinking too lean??? I have the stock map (as far as I know), K&N airfilter and the NGK Iridium plugs. Any ideas???

[DFWBiker]

Yep...high hydrocarbon readings and low CO are usually the result of a lean mixture. I'd imagine your O2 readings were high, as well. The original factory map is already fairly lean. Adding the K&N filter will make it even more lean since it flows more air than the OEM filter.

You probably need a richer fuel map.

This page helps explain how to read you emissions tests: Emissions Chart

[ This message was edited by: DFWBiker on 2006-03-30 10:33 ]

[Stiles]

DFW, high HC readings are typical of a rich mixture, not a lean one... although if it had a serious problem one would expect a higher CO number as well.

Rich mixtures and high HC can be the result of ignition misfires, bad temp sensors, bad injectors/pressure regulators or ECMs, among other things.

Too-lean mixtures produce high NOx on vehicles without catalytic converters with high 02 readings while CO stays low.

Just having HC and CO readings isn't enough, you need at least NOx and CO2, and 02 if possible and to know if this was an idle test or a loaded dyno test (IM240 or similar).

With that kind of HC reading and low CO, I'd look for vacuum leaks, worn spark plugs, clogged air filter/PCV or clogged/leaking injectors, then skewed air and coolant temp sensors. Check codes stored in the ECM first, even if the check engine light isn't on.

Also, change the oil and filter if it's near interval or past due as gas diluted oil can produce high HC tailpipe readings. You did bring the bike in for the test fully warmed up, right?

[ This message was edited by: Stiles on 2006-03-30 15:10 ]

[DFWBiker]

No...high HC merely indicates incomplete combustion of the F/A mixture.

High HC with low CO readings are typical of lean mixtures (or various vacuum leaks/ignition issues...which would probably result in a rough running engine). You'd also be likely to have high 02 and low CO2 concentrations with a lean mixture.

A rich mixture would likely show normal/low HC, low CO2, high CO and high O2 in an exhaust analysis.

A rich mixture can show high HC readings if there are other problems with the engine, such as ignition problems...fouled plugs, incorrect timing, etc.

However, I agree that more info is needed to be 100% sure.

[vanpraag]

Unfortunately, the only data I got back from the testing center showed the Co and Hc. the plugs only have a 2k miles or so on them. Oil is mid life for the change. Yes, the test was fully warmed up engine. First was the standard idle and then 30 seconds at 2500 rpm for the conditioning test. The engine seems to runs fine, no back fires. No indication of incorrect timing. Unfortunately, I don't have a tuneboy to check codes. Wish I did!!! Gonna check my plugs this weekend but I suspect they will look like the ones I took out when I changed em. Good coloration. I still have the Triumph airfilter and gonna put that back in as well. Since it's gonna be apart, I'll look for the usual stuff too...

[Stiles]

DFW, that depends on the vehicle and what's causing the problem. I've seen many cars fail IM240 or tailpipe idle testing for HC that were running rich because of vac leaks, bad 02 or temp sensors that caused the ECM to meter too much fuel - and had no other problems whatsoever, ignition or otherwise. The majority of cars that I've tested that failed for gross HC were running visibly rich while cars with very low HC ran good-to-lean and virtually never exhibited anything like a rich condition... and we're talking about literally thousands of cars over the last 10 years.

I know bikes are not cars (no cats on the bikes we're discussing) but closed loop EFI principles don't change.

Vanpraag, you can get a 5 gas test with printout from an independent shop that does emissions for a nominal fee. 2 speed idle tests can be done with lesser equipment -simple and cheap - so you might have to call around to find a shop with a 5 gas analyser with printer. The results from a 5 gas test will help you find the problem.

[vanpraag]

Okay, update, replaced the airfilter with the oem one. Went for retest and the Co came up .3 but the HC is still around 1900ppm??? Check vac lines good seal on the throttle bodies, etc... Does anyone have a Tuneboy in the Tucson area??? Gonna call the dealer to find out how much that's gonna cost, guess I'll have to have the paramedics standing by for the heart attack when they tell me how much$$$. :brk:

[unummyu]

Van,
Even with TuneBoy one needs an unlock code from Wayne as the original purchase price is for one ECM only. I think they are about $100 USD for additional codes. No such thing as a free lunch. Too bad your dealer isn't willing to help you out.