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Thread: Tunning For Better Throttle Response

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    Tunning For Better Throttle Response

    I have a 383 TPI in a 90 vette with a 7727 ecm I would like to tune for better throttle response, whats the best way to go about it as far as making changes in the the tune, so far I have limited my self to fine tuning the VE table and Timing table from a mail order tune and tcc lock up, highway mode, fans ect.
    383 TPI
    stock L98 113 heads
    stock TPI intake
    Headers and true dual exhaust no cats
    24lb injectors
    com cams 08-302-8 cam http://www.compcams.com/Company/CC/c...?csid=212&sb=2
    auto with 3.07 diff.
    52 mm throttle body

    I included my last data log using aldldroid.
    Attached Files Attached Files
    Last edited by eutu1960; 07-30-2017 at 03:43 PM.

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    On an related side note, what is your injector duty cycle on that build? I was nearly maxing out LT4 injectors (26 ish lb/hr @ 43 psi) at 50 psi on a 350 build.

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    Quote Originally Posted by Fast355 View Post
    On an related side note, what is your injector duty cycle on that build? I was nearly maxing out LT4 injectors (26 ish lb/hr @ 43 psi) at 50 psi on a 350 build.
    will give it a look see, with the stock tuned port intake and 113 heads the motor runs out of breath by 5000 rpm. so I am proply ok.

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    Quote Originally Posted by Fast355 View Post
    On an related side note, what is your injector duty cycle on that build? I was nearly maxing out LT4 injectors (26 ish lb/hr @ 43 psi) at 50 psi on a 350 build.
    you will have to excuse my ignorance but cant find injector duty cycle listed in the bin file. I do now my BPW on my data log is about 10.5 when going to about 4000 rpm. under the tables section I do see injector pulse width low offset vs base pulse with

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    Quote Originally Posted by eutu1960 View Post
    you will have to excuse my ignorance but cant find injector duty cycle listed in the bin file. I do now my BPW on my data log is about 10.5 when going to about 4000 rpm. under the tables section I do see injector pulse width low offset vs base pulse with
    1. Could you explain exactly what you mean by "tuning for better throttle response". Many ways to interpret -- want faster revs with throttle pop, bogging at throttle pop, slightly stalling at tip-in, etc.
    2. The Analyzer will give you everything you need to know about your injectors + much more about your tune here: http://www.gearhead-efi.com/Fuel-Inj...-File-Analyzer. Despite title, is NOT restricted to just S_AUJP v5. Will analyze any .csv, xls or xlsx file

    Sample:
    Injectorr Info.jpg

    HTH
    Last edited by 84Elky; 08-06-2017 at 03:29 PM.

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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.

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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

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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.
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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

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    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!

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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

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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

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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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    Quote Originally Posted by uncabob View Post
    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
    OK but I already have a large cap with the correct bin with the latency table for a large cap, are you saying I should switch to a small cap latency table or are you saying use the large cap latency table.

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    Fuel Injected! uncabob's Avatar
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    Quote Originally Posted by eutu1960 View Post
    OK but I already have a large cap with the correct bin with the latency table for a large cap, are you saying I should switch to a small cap latency table or are you saying use the large cap latency table.
    Nope: Sounds like you should be good. Sorry if I side-tracked you.
    Bob
    Don't force it, get a bigger hammer!

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