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Thread: Tuning for Mild Cam, Headers, etc....

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    Fuel Injected! Davis_1377's Avatar
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    Tuning for Mild Cam, Headers, etc....

    Been looking everywhere to come up with a good Spark advance table or any other things to help. Running a TBI 350 with Headers, dual flowmasters with Comp Cam 12-366-4 Lift: .520"/.515" Duration: 268°/280° Lobe Separation Angle: 113° Has ecm 1227747 $42

    If anyone can please help me with any of this id appreciate it. Im kinda new to this but have messed with it quite a bit so theres some smaller stuff i may not know. My map reading at idle runs about 60 kPa at about 550 RPM. Ive tried started working on its idle first to keep a good steady idle and lope but when it does start to lope right it looses its rythm.

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    RIP EagleMark's Avatar
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    That's not a mild cam. It's just beyond max for an EFI system. This one?
    http://www.jegs.com/i/Comp-Cams/249/12-366-4/10002/-1

    Operating range from 2000 PRM, not 0 RPM... hope your manual trans or have a high stall converter... then it goes to 6000 RPM so you need enough fuel there before you start tuning idle.

    You'll never idle Closed Loop at 60 MAP and 550 RPM. Start at 850, may be able to get it lower later. Idle spark around 22 degrees, stock is 16.

    TBI is a wet intake so the longer you idle the wetter the intake gets, worse with low vacuum/high MAP. So need to rev it up awhile after you make adjustments to dry it out, then see what data says for more adjustments.

    But idle is the least of worries right now. What is estimated HP of engine? What size injectors? What fuel pressure?

    This is not an easy engine to learn to tune on, here's some things we were collecting for starter tunes on built engines.
    http://www.gearhead-efi.com/Fuel-Inj...odified-engine.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
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    Fuel Injected! Davis_1377's Avatar
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    Yea thats the right one. I didnt know much at the time about EFI when i started this project. I got a 700r trans right now, no stall but does good, it dont try to die in gear and it takes off easy. Im guessing the hp would be around 230-250. Fuel pressure I have not checked but my blm and int stay around 128 if its right. The injectors ive not looked at yet either i just know they are stock. Ill try what you said in the mean time.

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    RIP EagleMark's Avatar
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    Quote Originally Posted by Davis_1377 View Post
    Im guessing the hp would be around 230-250. Fuel pressure I have not checked but my blm and int stay around 128 if its right. The injectors ive not looked at yet either i just know they are stock.
    That's a lot of cam for stock intake, TBI and heads! Let's hope it's more then 250 HP, but getting to the 6000 RPM range is going to be an issue.

    Your INT and BLM of 128! Not possible at 60 MAP and 550 RPM... Must be in Open Loop! System has to go Closed Loop to see fueling changes in INT and BLM.

    Don't do any WOT high RPM runs until you get some things figured out. Stock injectors and fuel pressure is no where near enough to fuel that engine, your going to be lean at WOT high RPM.

    Do you have any data logs? Post them up so we can see what is actually going on.


    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! jim_in_dorris's Avatar
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    What BCC is this running?
    Square body stepsides forever!!!

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    Fuel Injected! Davis_1377's Avatar
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    Here is a log file and its a ACSF bin i ran. There is a big hill at the beginning when i data logged. I also have a stage 1 and stage 2 bin that seems to do alittle better then stock. I meant my blm stays close to 128 when driving in closed loop. I dont have a heated o2 but im gonna get one later. I also have a throttle body off a 454 somewhere if it would help i could put on it, I dont know how these do on a 350.
    Attached Files Attached Files

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    Fuel Injected! jim_in_dorris's Avatar
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    Mark, this may be one of those special tunes with blm min and max set?
    Square body stepsides forever!!!

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    RIP EagleMark's Avatar
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    Well he said this log was ACSF so if I have that bin I could analyze the data well.

    Where did the Stage 1 and Stage 2 come from? Couple different companies use that name, one is reputable... still neither would be a custom tune for your engine, just a closer guess.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    RIP EagleMark's Avatar
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    ACSF was superseded twice to AMUR. I compared the bins and no big changes... looks like emmissions tweaks.

    End of your log has some idle time and BLM is 108, which is minimum, so it's taking out fuel and still needs more out. Rest of log BLM and INT are all over the place. No error codes. So this is exactly what I would expect for a stock chip and your built engine.

    If you know the Stage 2 is for a 350? I'd run it till you can tune or find someone to tune for the engine. The Stage 2s I have seen have less fuel at idle and WAY more spark. SO watch for and listen for Knock. Some of these chips have been known to remove knock retard....

    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! Davis_1377's Avatar
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    The stage 1 I got off this website. The stage 2 is a JET one I bought awhile back, I can upload them all if anyone wants to analyze them. After a min or so in the log where I set for a min before I took off it had a good idle. If I could change something for now to keep an idle like that I'd be pretty happy cause I got pretty good power with the stage 1 and 2. I can data log the stage 2 later and upload that also if anyone wants to see the difference.

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    RIP EagleMark's Avatar
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    The Stage 1 on the site is a Hypertech, not much change from stock, when you have time compare it. You'd be pissed if you spent money on it.

    I'd like to see the Jet Stage 2 as I never saw one, from what I read it would be best choice for you....

    BTW neither of those companies are the one I was referring to as not reputable.

    Clear BLM learn after you put it in. If I can see the file and a log I can point you in right direction. You still have a long learning curve ahead to get this right. By then you'll be like the rest of us and always tweaking something...

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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    RIP EagleMark's Avatar
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    The reason you started to idle better at that point was you went Closed Loop and fueling correction started, but it soon bottomed out.

    1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
    1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
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  13. #13
    Fuel Injected! Davis_1377's Avatar
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    Yea i wasnt all that happy when i figured out i paid that much for a stage 2 being not that much better. What company would be reputable? If you dont care ill upload the stage 2 to the bins page also. Yea i like tweaking as im either working on cars or building computers so i figured efi tuning would be a combination of both.

    Ill get a log for the stage 2 tomorrow after work and upload it. When you said my BLM and INT is all over the place, you think my stock o2 sensor would be right also? By the way on the highway anything it changes is not noticeable. There was also alot of hills so i can data log on a flat road which ever be easier. I dont know if i meantioned the headers are mid sized and 3" pipe, dual all the way back with dual flows.
    Attached Files Attached Files

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    RIP EagleMark's Avatar
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    Well I take that back, there's nothing in that Jet chip that would help over a stock chip for your engine. It's almost a stock chip, few degrees timing at WOT is about the only thing noticeable, all other changes are because I don't know what exact chip they were replacing to compare it to.

    Yea i like tweaking as im either working on cars or building computers so i figured efi tuning would be a combination of both.
    That's what happened to me!

    I meant my blm stays close to 128 when driving in closed loop.
    No it doesn't, maybe the average? Min and max are far apart. Idle is pegged at bottom taking out fuel.

    What company would be reputable?
    Well Jet just made it to not reputable?
    I thought you wanted to learn to tune? If you want to buy a chip PM me. I'll still help you learn one way or another. It does not happen overnight, I have years into this and still learn everyday. Every built motor is a little different, for that matter stock motors are or GM would not have a bazillion different chips.

    Just trying to help you get going... you can log, you can read chips so you can burn chips. Have you done anything to a chip yet? Did you read this thread?
    http://www.gearhead-efi.com/Fuel-Inj...odified-engine

    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! Davis_1377's Avatar
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    Yea I'm still wanting to learn. That's what I thought when I comoared the difference from jet and stock tunining, I knew then I needed to be custom.

    I've tried a few things on my own like dropping the whole spark advance table to compensate for the less vacuum from the bigger cam. The idle is better when I drop the timming down at a idle but if the rest of the table is still high and after its reved alittle the idle dont fall back down. If I knew where the graph would be good at mabe I can change fuel tables.

    I think what would help me also is knowing what all the stuff means in the definition and what it does that I can change in the bin. And what to start looking for when starting a tune

    I know its something I can be good at as I done some other things I thought would be hard and wasn't like rooting a phone and opening apps, building a public game server.
    Last edited by Davis_1377; 03-23-2013 at 02:18 PM.

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