High HC's

[Blown&Injected]

I am pretty sure I passed with the combo in my sig in the past, but this time I failed. I believe Maryland does/uses(?) the I/M 240 test.

HC = 2.5450 Cutpoint = 1.8000

CO = 12.3516 Cutpoint = 30.0000

NOX = 1.6462 Cutpoint = 2.8000

CO2 = 406.3211 Cutpoint = N/A

I am not happy with the O2 sensor, but it has not set any codes and the MAF has no screens - I am not sure I like the way that is working.

What can I do to pass?

I must say that the operator just stabbed the throttle when the car was to pickup speed and then right back to idle. So the car was just in a quick rev and idle situation for the entire test. Maybe 10% part throttle cruise, but really just a series of pops on the gas. The graph of the test results shows sharp spikes just at the beginning of every speed increase.


I must ask, even if I get no comment, what is clean piping/screening. I understand that there will be no comment on HOW to do it, I just never heard of it - sounds like dumping the exhaust under the car and pumping straight air in the pipe to the tail. If that is it, it sounds like more work than just fixing the engine!

THANKS!

 

[wlaukaitis]

I failed as well but I think our tests are different. I used to live in Herndon, VA and I know that the test there is nothing like the NY test.

Anyway, look for my post here, you can see my numbers are much worse than yours. I am not sure it you know the NY test but it is pretty nasty, the peeds range from 0 mph up to 59 mph!!!

Anyway, it turns out my cat was gutted but I have a new one installed and I turned the fuel pressure down from (line off) 46 (ouch!) to 41 and I found an intake leak on the upper plenum at the passenger rear side. I am waiting for the gasket so I do not have new numbers yet. I have heard fo guys here having to turn the fuel down to 32!!!

Was the test run in OD or drive? My car was ran twice, once on OD (first test, I don't have the numbers) and the second time in Drive which are the numbers posted.

 

[gofstbuick]

Try richening the mixture a little (raise fuel pressure). I was wondering if you could see an emissions spike (on the test results) at the moment you suspected he stabbed the accelerator? If so, that is probably the problem. The operator should driven the trace smooth. He/she may have gotten close to too many drive trace violations and had to blip the accelerator to stay within the drive trace (or the test would have aborted and required a retest).
Clean piping refers to inserting the sample probe into the exhaust of another vehicle to pass a failing vehicle.
Clean screening involves OBD2 vehicles only. The emissions analyzer is hooked up to the OBD2 link to determine how many monitors have been set. A specific number of monitors must be set to pass the emissions test. Clean screening involves the use of another OBD2 vehicle to pass the monitors test.
In many states, getting caught doing either one or both of these will usually cost a technician his/her livelyhood, may involve confiscation of equipment and hefty fines. The emissions analyzers not only test, but collect data. Clean piping and clean screening usually show up quite clearly on the data (the more greedy a person gets). But sometimes people will brag about how they got their vehicle to pass emissions. Usually these individuals are so proud of their vehicles, that it wouldn't be hard to track down a license number and match it to a station. The membership of this board has a wide array of different people with many different jobs and walks of life (from police officers to engineers). You wouldn't brag to a police officer about the great rock cocaine you experienced the night before, so why would you brag on a public forum about how you illegally got your car to pass smog? (especially if it is someone elses livelyhood you're messing with, no amount of money can repay an individual for having to start a new career all over again). The saying "loose lips sinks ships" is very true to life in some situations. I'll get off my soapbox now .

 

[ijames]

The dyno jockeys here in MD really love that digital style - stomp and let off, stomp and let off. Even when a friend complained, the manager wouldn't retest his car himself or let another driver do it. He just said "You failed. Have a nice day." or words to that effect. Good thing another friend was along cause the two of us were just enough to keep the car owner from attacking the guy. I set up my laptop with direct scan (use 4 fps) or turbolink and start it recording just before they pull onto the rollers. I make very sure they know what it's for, to record how well they drive, so I can see all the tps blips. I even showed one guy, and told him I'd file a complaint if I failed and he didn't do a smooth job. That was one of the times I fast passed . I really think the test should start with an "accelerate to 30 mph/hold/decelerate to zero" in about 20 seconds just to let them get used to the throttle, then start the real test. This style is why in my emissions chips I raise all the pe thresholds to the max so they only get the ae pump shot when they stomp it, they don't get the pe enrichment on top of that. Oh, here the testing stations are run by the state, so the testers are state employees. They no longer let independent businesses do the smog testing.

Joe, you have mentioned several times about raising or dropping the fuel pressure some to richen it or lean it out, but doesn't the ecm just shift the blms to get right back to the same fueling? When I was testing with an hc/co meter with my 72's, I got pretty flat results until I dropped the pressure over 6 psi from normal (down into the mid-30's), and I think my effect was more from pulse width issues than any enleanment. I need to get some testing time in on a car with smaller injectors, but I don't think my friend wants to drag out his machine any more, sigh.

 

[gofstbuick]

I always figure that there would be some minute changes to changing FP. Especially since some changes to FP can affect the KR. That is what I'm basing my experience on. I was going to get the car on the dyno (at the local community college) and do some testing this past spring, but didn't get a chance. I'm shooting for late summer, early fall (next semester) now. I'll be able to validate some stuff then.
Regarding driving the trace smooth, that is a good idea to monitor the TPS with TLink. In CA, we don't have much worries regarding driving the trace smoothly, because ASM is a steady state test, with only a 1mph +/- variation. IMHO, there are too many variables using I/M 240, BAR30, I/M 147 and it's other variations.

 

[ALXTTA 1]

Hi Steve,

My TTA failed the Illinois IM240 test several times with numbers almost identical to yours (except NoX, which IL doesn't test for.) Joe (gofst) finally helped me track it down to my converter just not getting hot enough to completely light off. After this realization, I have been tested twice since...and fast-passed both times. This last time, my CO read .000 and my HC was ~.104. I now have a standard procedure for testing:

1. When you reach the test station, park in the lot (unless there's a really long line) and wind it up to 2500 rpm for a good solid 5 minutes or more.
2. When you're on the rollers right before they are ready to test, ask them to "pre-condition" the car. Basically, they'll cruise at 30 mph or so for a minute or 2 on the rollers.
3. I also ask them not to blip the throttle too hard. Ask them to "lead" the graph a little when they see they are coming up to the big acceleration points.

 

[Blown&Injected]

Originally posted by gofstbuick
I was wondering if you could see an emissions spike (on the test results) at the moment you suspected he stabbed the accelerator? If so, that is probably the problem. The operator should driven the trace smooth. He/she may have gotten close to too many drive trace violations and had to blip the accelerator to stay within the drive trace (or the test would have aborted and required a retest)

Thanks all!

Yep, they gave me a print out that has several line graphs. There is a HC spike at the beginning of every increase in speed - the lines are over laid.

The cat is a 3" cat that is about 7 years old but has maybe been on and off the car for six months of run time - should be like new - looks new. I am sure I passed two years ago with the same setup.