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Thread: 85 K5 Blazer with TBI retrofit

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    Fuel Injected! rokcrawlin85's Avatar
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    85 K5 Blazer with TBI retrofit

    Figured I'd start my own thread for my logging, questions, ideas, tuning for my project. Any questions or ideas or thoughts I'll put here.

    So a little history,
    85 k5 I'm building for crawling and off road fun. Has a GM 350 HO that I've retrofitted with a 90 suburban 3/4 ton TBI. Using a harness from affordable fuel injection that removes the VSS and knock sensor and no EGR. ECM is 1228747 with the mods I've needed to do to be able to burn my own chips. Non computer 700R4. Its currently running ok but I know there's room for big improvement. IIRC I'm using a stock bin for a 7.4 with 4 speed auto. I'm now looking into using the stock 5.7 manual bin to tune off of. For the first chip I've smoothed the VE table and a smoothed timing table with a flattened idle area. I've turned off EGR, knock retard, and VSS. Seem like a good start bin to tune off of?

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    EFI GearHead ! EagleMark's Avatar
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    I'm probably not going to be much help for next few months but thought I'd point you in a few directions to help get you going. There's a lot of other help here...

    Look for Dave W performance Spark tables to start and maybe back off a few degrees because you removed the Knock sensor... or better yet re-wire it back in with matched ESC and knock sensor...

    Read this:
    http://www.gearhead-efi.com/Fuel-Inj...odified-engine


    The 8747 is a good ECM but not many of them so the mask/XDF has not had much work done. You may want to just plug in a 7747 and use $42? Now I've been told the 8747 will run a $42 chip too... but I never tried it. If you go that route there's tons of work done on the $42 XDF with notes that makes it way easier. Manual chip for 5.7L to start with would be ASDX. If not open $42 and use the notes anyway.

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

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    Fuel Injected! rokcrawlin85's Avatar
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    Thanks Mark, I like the idea of using the $42 mask for a detailed description of each item. I've actually tried the $42 mask chip in a $4f, it does not work. Had an instant flashing cel on startup. I tried because I like how much more the$42 mask had to offer. My general tuning isn't gonna be for max gains but rather a nice smooth consistent motor that's reliable. Hard to drag race a K5 on 37's. Not that I wouldn't like to race a few people now and then. I'd like to get some logs in and have some of you "pros" look at it and just give me a general idea what you see. I like to know why I'm making changes and not to just do it because so and so said so. I'm falling in love with tuning already

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    Super Moderator dave w's Avatar
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    This link has lots of good information: http://www.gearhead-efi.com/Fuel-Inj...Information-4F

    I'm not 100% positive, but I'm thinking the 8747 was used with either TH400 or Manual Transmissions. I don't remember seeing a TH700R4 using the 8747 from the factory. I think using a 5.7 liter .bin file would be a good place to start tuning with. Usually I set up the spark table first (with some smoothing), then course tune the VE table. I usually smooth the VE table after a course tuning the VE table.

    dave w

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    Fuel Injected! rokcrawlin85's Avatar
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    Dave, you are right, the suburban I pulled the TBI from was running a turbo 400 but my setup I'm using an '85 700R4 (stock). That's the link I'm using to get the files I need. I'm currently setup with the AKWH bin with what I believe the flags turned off for what I'm NOT running like EGR, VSS, and knock. Also using the "heavy duty" ADC file for logging. I have not logged anything yet. Just wanting to get an idea what people think of for my base bin to use.

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    Fuel Injected! rokcrawlin85's Avatar
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    Base Timing Smooth.jpg
    This is the current timing table smoothed with the idle area leveled out... is this a good start to build from???? also the bias has been removed so this should be the actual timing that the motor sees

  7. #7
    Super Moderator dave w's Avatar
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    I like the 3D timing map you posted. I'm not always in favor of a beginner removing the spark bias, because it can cause unexpected knock. I would suggest using the bias at first, then removing the basis after a few baseline data logs have been recorded.

    dave w

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    Fuel Injected! rokcrawlin85's Avatar
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    Got it! I always thought it would be easier knowing the true timing. But I'm trusting the pros to lead me right. Thanks for the insight guys

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    Fuel Injected! rokcrawlin85's Avatar
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    Is there a way that i can add an a/c idle raise to the $4F for using a winch? I'd like to flip a toggle switch and get the idle speed to raise a few hundred to help with the load put on the system? I know the $42 has it but the current $4F doesn't allow for that. And im no where near capable of adding it into the xdf without some serious help.

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    post your bin, and how much you want the idle to raise with the ac on.

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    Fuel Injected! rokcrawlin85's Avatar
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    Ok, here's the bin im currently working on. I'd like the idle to raise 200 RPM.
    Attached Files Attached Files

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    are you using the ac connector to operate a relay for your wench? here is the bin 200 up with ac on.

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    Fuel Injected! rokcrawlin85's Avatar
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    Nice! Thank you!! I have the a/c wire connected to a toggle switch that when flipped will idle up. The winch will still have separate power. The a/c idle raise is more for when i'm winching from outside the vehicle and need a little more umph from the motor. It will also be used when i turn my on board air on. (which is a converted stock a/c compressor)

    Which parameter is it in the bin that controls the a/c steps? What was involved with adding a parameter?
    Last edited by rokcrawlin85; 01-12-2014 at 06:55 PM.

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    I don't no in tuner pro, I used tuner cat to add rpms with ac on. if you wont a different rpm after you try it out post up again and I will change it.

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    Fuel Injected! rokcrawlin85's Avatar
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    Fair enough. I appreciate the help!

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