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Thread: Turbo tuning for the first time

  1. #1
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    Default Turbo tuning for the first time

    I finally got my turbo kit built and installed and am turbo tuning for the first time. I upgraded to cos3 and installed a 3 Bar map sensor. I followed the Auto VE tutorial however it feels like after about 10 to 15 min the car gets back into closed loop. After I get up to temp and start to drive the tune feels pretty good and is very rich as expected. I run 11:1 and 12:1 most of the time but after about 15 min or so it starts to settle in at 14.5:1 and seems to try and hold that all over the place. Can someone look at the attached tune to see if I am in open loop? Also the spark timing is all messed up, it feels like spark is wayyyy too late burning on the way out throught he turbo. I am thinking of taking a spark map from a CTSV as a starting point. Is this a good or bad idea?

    Here are some pictures of the kit I built:









    Couple of assembly:





    Here she is all "done"


    Attached Files Attached Files

  2. #2
    Lifetime Member Tre-Cool's Avatar
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    ok, quick glance.

    u need to change b3647 so that there are no 1's. set to 1.01 if in EQ. .99 in lambda or 14.5 afr.

    max out b4203 also


    what injectors are in this & do u have vacuum line to the FPR?

    any other engine mods?
    Last edited by Tre-Cool; May 13th, 2020 at 12:25 AM.

  3. #3
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    Thanks for taking a look Tre-Cool!!!

    I have no vacuum regulator, I am using an inline Corvette C5 filter / regulator with the LS1 stock fuel rail / intake . The injectors are a set of "flow matched" decapped E85 injectors (ebay) from a 2006 Tahoe (I think). When changing the injector parameters I used the attached spreadsheet for flow data and took all the timing data from a 2006 Tahoe tune. The 5.3 LM7 engine is bone stock block and heads with the LS1 intake, water pump and accessories and has an unknown amount of miles on it.

    Last night I copied the high octane spark map from a stock CTS-V tune into mine and WOW WHAT A DIFFERENCE!!! This thing gets up and goes now. I now only have some detonation / stumbling in very low RPM and high boost. New tune attached (before your suggested changes)

    Once tuned in should I always stay in open loop or should I switch back to closed loop?

    Injector pictures (I like pictures)

  4. #4
    Lifetime Member Tre-Cool's Avatar
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    because you have 2 turbo's you can still run closed loop. generally single turbo's wont though.

    To tune the ve you need to be in Open loop at all times, not just when in PE.

    depending on what your iat are like. I would take an easy 5 degrees off the entire map. remember the cts-v is a forged piston motor. yours is not.

    actually, have a try with this.new-map tune with autove openloop-cts-v-high-octane-spark_0000.ctz

    i've richened up the desired pe fuelling & the throttle enablers, since you can be in boost even with 30% throttle. also below 115 kpa you will be using the open loop tables. then above that it switches to the pe enrichment.

    you didnt say if you were running e85 & the amount of boost.

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    Thanks for the map update Ill look at what you changed. I was really rich already. I am actually thinking of going back to the low octane cts-v spark table and changing my map scalier slightly to lean the whole tune up a bit. When I first moved from the 1 bar to 3 bar (changed scalier from 94 to 305), my key off MAP values were slightly low. This change should give me a bit more resolution up high in the spark table as well right? Now that I am tuning and learning it seems the MAP is important for spark as well since it is based off of cylinder volume and that is derived from the VE table. Did not think about the dual turbo impacting closed loop but it makes sense because fuel trim is done per bank right? I have also only ever had my logging map set up for rpm and KPA with wideband o2 as the data field, i recently switched that to knock however just learned via you tube last night I should monitor knock via rpm and grams per cylinder to align with the spark map. I created a new map last night to log rpm / grams per cylinder.

    Ill attach some data logging to a future post once I am able to do some tuning runs.

    I am running 92 octane pump gas but would like to move to e85 once I figure this tuning stuff out. I think I also need to upgrade my fuel pump (really should now)
    My boost goals for this stock motor is around 8psi however I spiked to 20 a couple times after moving to this recent map. I want this motor to get through this summer however I am starting to build a 5.3 for boost, to replace this one once I blow it lol.

  6. #6
    Lifetime Member Tre-Cool's Avatar
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    i updated your map with the 3 bar figures i use.

    you dont want to mess with that. if you run out of spark g/cyl in the maps. it's easier to modify your injector flow rate & thus your ve maps.

    typically i would setup the tune to max out the 1.2 gcyl with 8~10 psi. then use the custom efi area to start removing timing based on boost.

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    I can't open he tune file. I get a version error. I am on 7.5

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    Lifetime Member Tre-Cool's Avatar
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    im using v7.5.28. should be the latest public version.

    also with the fuel reg, i've heard of far too many people where the factory reg fails or just doesnt work properly from the get go.

    can you put a fuel pressure guage inline somewhere to monitor it?

    i've personally seen, tried to tune a car where the pressure would slowly build up pressure. you could hear the pump noise change as the pressure increased, so that was the give away

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    I just upgraded to 7.5.28 and can open the file now. Looks like you made quite a few changes. Before I was able to open it I took 5 degrees out of my tune and made the other changes you recommended and went for a log drive yesterday. I also turned my boost down again (waste gate is just barley closed) however I still hit 15-18 PSI and I haven't even gone WOT yet. The most I have given it is 75% throttle or so. I don't think I am being very nice to the motor every time I come off boost over 5 PSI or so I am blowing blue smoke and pushing oil out of my seals and valve cover breather. I just have a single small air filter on the valve cover PCV lines. Is this a sign of bad blow by, too much boost, too much spark advance or something I am not thinking of? I have plans to build a better motor for the car this coming winter but I would like to get this one through the summer and fall. I attached the tune and log from yesterdays run, can you take a look and give me some feedback?

  10. #10
    Lifetime Member Tre-Cool's Avatar
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    that log looks ok for boost. 150kpa and seems to hold. so thats only 8psi. good base to start with.

    i sent u a pm with my contact details, you need to setup the logger a bit better, your logging a bunch of stuff you dont need.

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