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Thread: Tunning For Better Throttle Response

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  1. #1
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    basically when cruising say at highway speeds if I go wot it seems like its slow to respond, lots of noise but throttle lag, almost like turbo lag. I will try the file analyzer.

  2. #2
    Fuel Injected! 84Elky's Avatar
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    Analyzed your log. Files attached. Took about 10 min. because had to change log column headings in Analyzer. In the future you can just load the Analyzer and your log file and go.

    Some comments about your log
    • It had 2 bad samples - one with bad Spark and one with bad BPW. Very unusual to see this which indicates other problems
    • Something is wrong with your Spark Advance. Look at the attached file (8d.xlsx). You'll see a large # of samples where the difference between SA-TDC and SA-REF is not 6*. Must always be 6* because that's what your BIN contains as the Base SA. Have you properly set the timing with the bypass line disconnected and ensured you see 6* at the timing light? If not, must do! Sort the file on the difference column I added and you can immediately see the problem.
    • SA tables seem extremely hot. Some alum head engines run with this high advance, while other use approx. half of that. Search for L98 BINs and take a look and make sure you're using what you should.
    • Your PE SA .vs RPM table has no entries, which is good for the amount of SA you're using, but if that is lowered considerably, might consider repopulating that table
    • For some reason, BLM Learn is disabled when it should be enabled. It's always disabled when in PE, but you have many samples where it's disabled when it should not be because coolant temp is high enough to enable it. It's only enabled when coolant > 122 (your setting) and when AFR = Stoich; otherwise not. AFR can only deviate from Stoich when in PE, in OL and not in PE, and in Highway Fuel Mode. In virtually all the disabled samples, AFR is NOT stoich and you're not in PE and indications are that Highway Fuel should be disabled. Don't understand this. I'd search for how do disable Highway Fuel and Spark and disable it until you can find problem.
    • The good news, BLM's look good and injector Duty Cycle is OK.

    The large # of erred samples would indicate a bad logging connection, bad ECM, etc. Something's not right, but can't tell what.

    Not good news, but at least you now know.
    Attached Files Attached Files

  3. #3
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    timing is set at 6* with the bypass wire disconnected and is rock steady, I engaged highway mode a few weeks ago and to disable it I just need to change the mph for highway mode to 255mph, thanks for running the file for me, I always have had those bad samples, I will have to to some more data logging with highway mode disabled. timing tables are pretty close to what came with the mail order tune I started with, I have the oem bin. I have also replaced all the wires and connectors from the HEI dissy back to the ecm along with everything in the dissy, I realy need to pull the rest of the engine harness and give it a good going over, I also tried different ecm's. I have read some were about emi problems with the HEI dissy and sensors, maybe something to do with my spark problems.
    Attached Files Attached Files

  4. #4
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    well I made another data log this time with Highway mode disabled and using Tuner Pro RT instead of ALDLDroid.
    Attached Files Attached Files

  5. #5
    Fuel Injected! uncabob's Avatar
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    Do you have the large cap HEI? If so you might check Spark latency table if it is included.
    Don't force it, get a bigger hammer!

  6. #6
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    Quote Originally Posted by uncabob View Post
    Do you have the large cap HEI? If so you might check Spark latency table if it is included.
    I do have the large cap, I will look for the spark latency table. thanks

  7. #7
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    I found a Spark Latency Correction table. from what I have read it is for "It corrects the timing based on the A/C alternator effect of the pickup/ reluctor." and thats about what I know at this point

  8. #8
    Fuel Injected! uncabob's Avatar
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    Quote Originally Posted by eutu1960 View Post
    I found a Spark Latency Correction table. from what I have read it is for "It corrects the timing based on the A/C alternator effect of the pickup/ reluctor." and thats about what I know at this point
    Try searching for spark latency tables for large cap on Corvettes over on third.gen. IIRC it has to do with the larger radius
    and the time it takes the rotor to move from point to point. It made a big difference for me.
    Bob
    Don't force it, get a bigger hammer!

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