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Thread: 3800SC advanced fuel tuning question

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    3800SC advanced fuel tuning question

    My first question is how to adjust the "tip-in enrichment". Which would command more/less fuel based on percentage of rate of throttle change, basically how fast the throttle was applied. Currently, even just "blipping" the throttle, AFRs go insanely rich then lean/level out once throttle is constant. Which table controls this function?

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    My other issue is when I initially started working the MAF tables, the weather was pretty warm. I got the AFRs down to 11.0 (running rich on purpose for the initial tuning). Parked the car for a few weeks while dealing with some stuff, the weather is now cold and now my AFRs are insanely rich... like 9.2 rich. I didn't change the MAF table, so what gives? The colder the weather, the richer it runs.

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    Possible something in the acceleration enrichment settings could help you with the rich blip of the throttle but you could just be entering PE and it's smacking it with fuel right away before the supercharger sends all the air through the cylinder heads.

    Post your tune file.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

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    I don't meant to be a noob, but how do I post my tune on here? Its my first time posting on the forum.

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    It's in the advanced reply, then click the attachments icon.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

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    How's this?


    RICH 1.hpt

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    Quote Originally Posted by adalhall View Post
    My other issue is when I initially started working the MAF tables, the weather was pretty warm. I got the AFRs down to 11.0 (running rich on purpose for the initial tuning). Parked the car for a few weeks while dealing with some stuff, the weather is now cold and now my AFRs are insanely rich... like 9.2 rich. I didn't change the MAF table, so what gives? The colder the weather, the richer it runs.
    To answer this question is pretty simple. Look at your MAF curve, it's smooth for a little bit then takes a dip and past like 9,000hz it takes a huge jump back up and that's a big reason for it adding more fuel. That large bump is adding a ton of fuel. The MAF curve needs to smooth all the way through with no dips or bumps. It must stay constant for no wild changes in fuling.

    Also look at your commanded AFR under PE. You have it commanding 11.0 but you still have the ADD vs RPM table active. That table adds the commanded AFR based on time and rpm like it says it does, so the longer you stay in the gas it's going to keep getting richer. It's adding anywhere from .8 to 1.8 to the AFR and that's why it's dipping far below 10.0 AFR.

    Just zero of that entire table to stop it, that way it will only command what you have put in the BASE AFR table.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

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    I never set any of those tables. Orignally I ordered a ZZP 1.0 PCM for Fiero swap, but I spec'd it for a 97 motor because I'm using a 97 harness and PCM. However, I'm running a zzp ported 99+ TB and MAF and had to completely re-tune the MAF table because it was so lean. I started with copying the MAF table from a stock 99 GTP tune I got from the repository, then tuned based on a few datalogs and general "test drives" making adjustments as I go. The only other tables Ive messed with is the spark table and the trans upshift speed settings as they were set so high it wouldn't upshift during WOT. I have disconnected the OE o2 senor and just running wideband since I only have 1 bung in my exhaust.

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    You need that o2 sensor if you want to tune correctly, otherwise you must run open loop only.

    It's never going to be the same if you try and run closed loop with no o2 sensor. Weld in another bung for the upstream o2 sensor.

    It doesn't matter if you didn't change those other tables, I was more just saying that is exactly what the computer is trying to do. You'd have to change the tune if you want it to stop commanding different AFR's.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.