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Thread: Vortec EGR System?

  1. #31
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    Quote Originally Posted by gregs78cam View Post
    I can tell you that on our '99 Grand Am with 3.4L, EGR not functioning reduces MPG by 10%.
    Funny thing, my grandmothers '03 Alero 3.4 that is driven only in the city increased its MPG over 20% with a tune, running disabled EGR.
    Last edited by Fast355; 06-02-2013 at 05:51 PM.

  2. #32
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    Quote Originally Posted by 1project2many View Post
    Mileage gains, if any, are secondary. EGR reduces combustion chamber temps to keep NOx levels lower. GM must have seen a need for more EGR under higher load on the L31 so that's when it's active.

    Be careful not to strip protective coatings / platings from components during cleaning process. Acids and bases are both very capable of doing that. I wonder if the "electrolytic rust removal" process would be effective here. It does a great job removing paint on parts that aren't rusty. I wonder how it will work on carbon?
    Makes sense with the retardedly high gearing and tight torque converter they used that the engine would be prone to creating NOx emissions trying to accelerate.

  3. #33
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    Quote Originally Posted by Fast355 View Post
    Funny thing, my grandmothers '03 Alero 3.4 that is driven only in the city increased its MPG over 20% with a tune, running disabled EGR.
    There's got to be some differences here we are not looking at like:
    1. Elevation? Greg and I are at 2000 feet.
    2. Tempreture? We rarely hit 90 in summer. Cooler all year then you.
    3. Fuel? I think we've had this discussion before but is E fuel there's the same as here? Refiners are close to texas so is fuel fresher? It's old by the time it gets here? I really don't know where our fuel comes from.

    Fuel: In Closed Loop my WB reads AFR of 13.8. E10 is supposed to be 14.1, do we have more E in out fuel? IIRC last summer I did some MPG data and the expense on Non Ethanol was well worth it.

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  4. #34
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    Just found some strange differences in EGR operation from old TBI engines $42 to the 0411 PCM I'm using in this Vortec engine.

    First there's SO MANY more parameters defined.

    Second $42 looks like EGR is always on under 50% TPS and if above 1.95% TPS after enabling at 3.12% TPS, with complete fueling compensation tables and up to 5.98 degrees spark added.

    Vortec with 0411 PCM = no parameters and data showing EGR on during acceleration and off at all light cruise. Got me curious so I'll be watching data to see what it's actually doing.

    Maybe EGR is why I can get better fuel mileage from an old TBI truck then I can with a 1998 Vortec and 2002 PCM and OS?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
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  5. #35
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    that would be a hilariously depressing explanation, considering what it costs to play with OBD1 compared to OBD2.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  6. #36
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    The EGR system does reduce combustion temps and thus reduces NOx emissions, but at the same time it is effectively reducing the displacement of each cylinder by partially filling it with inert exhaust gasses that will not burn. This is why when the EGR system is active the fuel system is designed to deliver less fuel. That is where the old and partially true "myth" that removing the EGR valve from an otherwise stock engine would "burn it up" because it would run too lean. Of course, that myth was started back in the carbureted days where the EGR was completely vacuum operated and the carburetor was jetted leaner and the enrichment systems took care of adding the proper fuel under load. Although I have never personally seen a carbureted vehicle actually experience some sort of engine damage by removing the EGR valve, I could see where it might be theoretically possible if the carburetor were left untouched. Throw in fuel injection, though, and all of that changes somewhat. But, like I said before, different engine configurations are going to react differently and you could also go a few steps further by figuring in ambient temperature, the fuel, elevation, vehicle weight, converter stall speed, and gearing etc.... Which would explain why different people experience either mileage losses or gains by disabling the EGR system. This is why on my personal vehicles I have always just disabled the EGR system. Not only is it one less variable to work around, but it is also fewer components that can fail and less crap cluttering the engine bay. About using strong cleaners and stripping protective coatings, I am looking at solutions for reconditioning parts where you would purposely want to remove those coatings. I will post some results on cleaning up the intake and what I used but I will definitely strongly warn of any dangers to both the parts and the person handling the cleaners. As far as any "home-brew" cleaners that I come up with I may eventually share the recipe if it seems to work well and be worth the effort of making, but I will definitely caution people to the dangers of them as well.
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  7. #37
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    Well, even the TBI engines still used a vacuum operated EGR valve that they controlled with a solenoid, but it was still an ON/OFF type valve. Aren't the newer electronic EGR valves "variable" in that the pintle is opened in percentages ? That would explain some differences at least.
    1999 GMC Sierra 1500 standard cab long bed 4.8 V8 2WD - A work in progress.
    2000 Grand Prix GT sedan 3800 - My new daily driver inherited from the wife via the insurance company totaling it out after a minor collision.
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  8. #38
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    i think GM gave everything the "linear" EGR setup in 96, a couple of applications got it before then. and before that, EVRV, positive backpressure, negative backpressure, digital, etc.... lot of different systems all occuring at the same time.
    1995 Chevrolet Monte Carlo LS 3100 + 4T60E


  9. #39
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    I hadn't even thought of coating on an intake? But I guess if I were in the cleaning process I would...

    If you think about carburators they are coated. This I was taught in high school auto shop, we had one that someone had scratched the inside of a float bowl with a screwdriver in cleaning. Well without the coating it would sweat fuel!

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  10. #40
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    Quote Originally Posted by RobertISaar View Post
    that would be a hilariously depressing explanation, considering what it costs to play with OBD1 compared to OBD2.
    Just the limitations of what can be done is depressing. Locations are all hidden, you can add things in EFI Live by including them in a CAX file if you have locations. One CAX file I have for lean cruise works, but not nearly correct. newest update will not allow changes to their locations, there's no way to add, change or correct descriptions... the limitations are endless compared to TunerPRo RT...

    TunerCat is much more forgiving for old software as you can add to and edit definitions with the TDF editor.

    That said the xdf for 2002 OS is coming along with using dimented24-7 disassemble for 2001 OS but being careful as some locations have changed, many tables are identical in different place.

    RoadRunner works with all three softwares...

    But I think some of the missing items in EGR case is because of MAF compared to speed density? EGR gas takes place of some of VE so fueling needs to compensate. Wouldn't the MAF do this?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  11. #41
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    Quote Originally Posted by pmkls1 View Post
    The EGR system does reduce combustion temps and thus reduces NOx emissions, but at the same time it is effectively reducing the displacement of each cylinder by partially filling it with inert exhaust gasses that will not burn. This is why when the EGR system is active the fuel system is designed to deliver less fuel. That is where the old and partially true "myth" that removing the EGR valve from an otherwise stock engine would "burn it up" because it would run too lean. Of course, that myth was started back in the carbureted days where the EGR was completely vacuum operated and the carburetor was jetted leaner and the enrichment systems took care of adding the proper fuel under load. Although I have never personally seen a carbureted vehicle actually experience some sort of engine damage by removing the EGR valve, I could see where it might be theoretically possible if the carburetor were left untouched. Throw in fuel injection, though, and all of that changes somewhat. But, like I said before, different engine configurations are going to react differently and you could also go a few steps further by figuring in ambient temperature, the fuel, elevation, vehicle weight, converter stall speed, and gearing etc.... Which would explain why different people experience either mileage losses or gains by disabling the EGR system.
    Take $42 for instance. If EGR is not disabled properly? And EGR removed? It still cuts fuel and adds spark when EGR is enabled!!!

    Wonder why your running lean and pinging?

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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