Engine/Transmission (1998.5 - 2002) Another CO emissions question

[JGarcia]

I just had my first emissions test here in Denver (Aurora, actually), and was told my opacity level was 18. 9, with 20 being the allowable limit. I don't feel very good about the high level, and was wondering what mechanically might cause a high opacity reading. Is this way out of the norm? My truck only has 34,000 miles on it and I worry that the testing might be even a closer call next year!! By the way, I tested with no fueling box on. Any input is appreciated!

Thanks,



JRG

 

[RustyJC]

Did you test on a load-type dynamometer? If so, at constant load/speed or variable load/speed? Opacity is "smoke", so your tighter torque converter could generate more smoke if the testing regimen included acceleration from idle where the engine is required to produce high torque at low rpms - the stock torque converter would let the engine rev up more (and more quickly) for a given acceleration load. Obviously, the ETC fueling calibrations in the stock ECM/VP-44 system are based on the stock torque converter, so they won't be optimized for the 89% DTT converter you're running.



Meeting emissions requirements is one reason the stock torque converters are as "loose" as they are.



Just a suggestion - if you didn't, you might want to dose up on one of the "smoke reducing" fuel additives before testing next time.



Rusty

 

[mschoenheider]

I just had my 96 tested at Colorado Diesel, and they said the limit was 30. I'm not sure what the scale is, but I doubt it would be different for different years, but could be.

The max I got was in the 18 range also.

The test is pretty simple, they run the truck up to 60 mph in 4th on a manual, 3rd on an auto, and then with the truck at full throttle, turn the load up on the dyno to slow the truck down to something like 40 mph, taking opacity tests at certain mph (I think they were 55, 45 and 40)

I would check again if the limit really is 20 for you or 30.

Mark

 

[RustyJC]

JRG,



Is this the test your truck went through? If so, did the converter stay in lock-up or unlock during the load increase/speed decrease?



If both the DTT and stock converters would stay in lock-up, then we can rule the torque converter out as a factor. If both would unlock, though, the DTT converter (because it's more efficient) would be running at a lower engine rpm at a given road speed than a stock converter, right? The lower rpm/higher torque regime of the DTT to generate a given road BHP would tend to generate more smoke than the higher rpm/lower torque characteristic of a stock converter. Also, the higher efficiency (lower slippage) of the DTT would mean that it would take more dynamometer load to pull the speed down to, say 50 mph than a stock converter. If that's the case, the engine would be working against a higher dynamometer load at a given road speed with the DTT than with the stock converter.



I can't speak to specific Colorado limits, but it would stand to reason that the 2001. 5 24V would be expected to run cleaner than a 1996 12V - the tighter federal emission standards were a primary reason for the introduction of the 24V.



Just offered as some food for thought... ... .



Rusty

 

[K_Arts]

JGarcia,



It sounds like to me that shop that you took your truck to is a little on the misinformed side.



Colorado state limit for Opacity is 30%. I find it very hard to believe that your truck did 18. 9% with only an EZ box (according to your sig). I know several people who have had their trucks tested with just and EZ box and none of them have seen above 10%.



When I tested my truck last year at Colorado Diesel, with the DD2's in I was at 10. 2%.



At 18. 9% your truck must smoke like a dozen Freight Trains. . LOL Cause at the 10% that I have, I my truck smokes like a freight train and I can bury a row of cars behind me with just a little tap of the go pedal



Kev

 

[JGarcia]

Thanks, all, for your input. I think the first step is to go to someone reputable next time. When I'm stock, I never see smoke, so I think K_Arts is correct, and there's a good chance it wasn't a reliable test. Also, glad to know about the limit being 30%. I hadn't thought about the impact of the transmission upgrades, it just goes to show once again why this site is the best one around. You guys are really a great help and source of information.



Thanks again, JRG

 

[Bandit1]

if the TC would be out of lock up wouldnt that cause it to smoke less, therefore lowering your smoke level? if i am understanding this right then just add a mystery switch for the test force the TC to stay unlocked and you should be more than fine. please anyone correct me if i am wrong.