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Diesel E-tests *update*

Discussion in '1982-Present GM Diesel' started by tRustyK5, Jun 13, 2005.

  1. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Multi part post here.

    First of all, who here has to E-test there diesel C or K trucks?

    Dyno test or ??

    Manual tranny or auto ??

    Some of you may remember i had a really hard time getting my truck to pass the emissions test in Sept '03. Fresh oil and filter, brand new air filter, rebuilt IP (stock fuel rate) rebuilt injectors, timed dead on the money. Here they have a tech (I'm using the term loosely) drive your truck on the dyno to simulate real world conditions. The test runs about 2 1/2 minutes...first part is the truck running down the 'road' at about 25 mph. Various accelerations to different speeds. The last part of the test is a WOT run from 15 mph to 60 mph.

    Our max allowable opacity is 30% which i think is artificially low. Many other test parameters I've read about have a 40% max opacity.

    The reason my truck kept failing was due to the way it was being driven on the dyno. With a 465's wide ratios it's very easy to bury the probe in soot if you're an idiot. What they'd do is try the last part of the test starting at 15 mph and they'd be lugging it out of the basement in third gear, then shifting at about 2500 rpm into 4th and mashing the stupid pedal again.

    After the first 'fail' I got a graph of what the opacity levels were throughout the test and at every shift point it would spike to ~50% for a few seconds until the R's built up again. The truck actually runs very clean and smoke free in the real world, and really there isn't anything more i can do to the motor that will make it run any cleaner. I never go WOT at low rpm's, I roll onto it and as the rpm's build the hammer drops. If it was driven that way on the dyno (and shifted at a higher rpm) it'd pass with flying colors.

    So, I'm due for my E-test sometime between now and July when my insurance comes due. It's been stressing me out a bit, and then while i was just about to fall asleep last night i had a flash of brilliance...i think. I'm going to install a throttle stop on the gas pedal, limiting things to ~ 1/2 throttle. I'll try and drive it as stupidly as possible with it on there just to see if I can make it belch smoke, and also to confirm I still have enough throttle to make 60 mph (with room to spare)

    I can't think of a reason this wouldn't work, and I've found the perfect spot on the gas pedal mechanism to accomplish this.

    Thoughts? Feedback? Anyone else have trouble getting the 6.2 to pass an E-test?

    Rene

    Update 07/09

    Went and got it E-tested this morning. The tech still can't drive, blew a shift and had to restart, then lugged it pretty badly and it still passed easily. Max opacity was 24%.

    Last week I installed a small aluminum block on the throttle linkage plate under the dash. I set it so max throttle position was artificially limited to about 60%.

    As badly as it was lugged and stuff on the dyno the guy could not overfuel the motor bad enough to get it to fail.

    The throttle stop doesn't really affect normal driving and I'm in no rush to remove it. I so rarely need more than about 60% throttle anyways...

    Anyways, if anyone else has trouble with an E-test I think this is an easy way to help your truck pass. The max allowable limit here is a pretty low 30% opacity.

    Rene
     
    Last edited: Jul 9, 2005
  2. BurbLover

    BurbLover 1/2 ton status

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    Let's see. Here in El Paso County in Colorado, we have to test diesels. I beleive the limit is 25% opacity IIRC. Test consist of the dyno. Tested at idle, then 45,55, & 65 under load simulated by dyno. I failed the first time last year due to too much air getting in. SInce I've developed some problem, I'v held off renewing the tags until I can get the fuel leak fixed.

    BTW, mine is an 84 K5 w/ 6.2, 3.73s & auto (700R4).

    Good luck with your test. Your limiting switch does make sense. Seems like it would require the tester to increase slowly effectively lowering the wide open throttle idea. Just hope there isn't some rule about limiting it somehow.
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    If he says it feels sluggish I'll just tell him all about how slow NA 6.2's are...:whistle:

    He'll have to work pretty damn hard to find my limiting device.

    Rene
     
  4. Robert79K5

    Robert79K5 1/2 ton status

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    Thats too bad you have to go through all of that. Im sure it's a matter of time before they start regulating diesel emissions here.

    So what exactly is opacity? Intuition tells me that its the ammount of soot contained in the exhaust?
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Yes, opacity is basically the density of the smoke.

    Rene
     
  6. mcinfantry

    mcinfantry 1/2 ton status

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    how does it work with vehicle age?
    is a 67 deuce and a half tested?
    gas truck converted to diesel?
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    My truck is 25 years old in sept and is a gas truck converted to diesel...they don't care. There is no magic cut-off for age here.

    my only hope would be to increase the GVW to 5001 kg (11,000 lb, and this would exempt me from having to E-test) but because i have a K5 (classified as a 2DR SW and runs car plates) I can't even do that. Thank God they don't get sticky enough to enforce car bumper heights for my K5. :blush:

    Anyways, I know plenty of guys running mid 60's iron and having to pass the E-test. Not sure what they base the numbers on seeing as anything pre-68 had no emissions controls whatsoever...

    IMO, it's just a big hidden tax grab, and has next to nothing to do with the environment.

    Rene
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Update at bottom of original post.

    Rene
     
  9. jarheadk5

    jarheadk5 1/2 ton status

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    Sweet! Amazing how stupid people are, eh?
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    These guys have a corner on the market for stupidity...

    At least I know I can get it to pass easily now, and if anyone else has trouble the throttle stop really works. In my case it doesn't even affect normal driveability either.

    Rene
     

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