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Thread: Major tune issues

  1. #1
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    Default Major tune issues

    Ok, here's the situation. I have a stock LQ9 in a truck, only mod is ported heads and milled...10.6:1 compression. I bought EFI live several months ago and found out on logging that I was having massive KR at wot and my LTFTs were like 10%. I sent this to my tuner and he said I had an air leak somewhere. Fast forward to today I changed out my intake manifold gaskets and throttle body gasket. Logged after that, same thing. 7-8 degrees of KR at wot. We then added 2.5% to the VE table, and 5% to the MAF table below 5000hz and 15% to the table above 5000hz. My o2 readings are looking much more suitable (.900-.930mV at wot versus .750-.800mV before the changes) but I'm still getting the KR and now at WOT around 4500-5000 rpms the engine starts feeling like the power delivery is "wavey" and or slightly surging. I'm still wondering if I have an air leak or what was going on. I dont know what could be leaking. Other than the changes I made, I'm running a stock GM 2002 LQ4 tune. The first log I am attaching is from May, the next one is right after the gasket swap on the stock tune, and the final one is with the fueling changes. If I put the truck in 2nd gear and punch it from like 40, it seemed with the final changes that it pulled good with no KR, but it only does 14 degrees of timing? Whenever it tries to bump up to the high spark table, it instantly bursts 7-8 degrees of KR.
    Attached Files Attached Files

  2. #2
    Lifetime Member mr.prick's Avatar
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    Have you reduced the Knock settings at all?
    You should not rely on NBO2 voltage for AFR and
    adding X.XX% to MAF and/or VE blindly is generally looked down upon
    as a tuning technique.
    LTFTs don't look too high in the final log, this may indicate you don't have a leak.
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    Quote Originally Posted by mr.prick View Post
    Have you reduced the Knock settings at all?
    You should not rely on NBO2 voltage for AFR and
    adding X.XX% to MAF and/or VE blindly is generally looked down upon
    as a tuning technique.
    LTFTs don't look too high in the final log, this may indicate you don't have a leak.
    I will not mess with the knock settings because I dont have enough experience and want that safeguard if indeed this is all true knock (which I believe it is). I dont have a wideband, so going off the narrowbands is all I have. I really just want this thing to run at WOT without any knock. I've been running on a stock LQ4 tune forever and it's just a dog. I've been waiting to change out the gaskets almost all summer and finally got it today but that didn't change any of the problems I was having before. What are the next steps I should take? BTW, my tuner is Justin Gadberry, I'd love to have him tune it live but he's not going to be in my state any time soon I believe. This issue Ive been having is really holding me off from adding any other mods because I need to get it running right first before compounding the problem. I really did not imagine that adding ported heads and increasing compression was going to screw things up so bad.

  4. #4
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    your strategy for combating kr and the lack of fuel is fine, for now. i'm assuming that you are using 93oct fuel, anything less is not adequate for the mods you posted. o2 values of less than .900mv is not good enough. since you do not have a w/b, it's ok if you just tune to .915mv using the nb o2 sensors, .920mv to or higher is probably too rich. wot tuning takes place on the last 1/3 of the entire load colums of the ve table, so 2.5% encrease is a good target. the maf table is way too high, instead, try 2% encrease from 8khz to the top. take the stock high oct. timing table and subtract 2* deg from .44gm/cyl to .120 or what ever the max is on your table and 3200 to max rpm colums. the last log that you posted seems that too much timing was removed. make a wot run with these settings, and report back. the other area that needs tuning with your mods is the low to midium load areas, which is indicative of the large positive ltfts, add 4% to the ve table in those areas, but do not touch the idle area, which is the 400 to 800rpm colums. i would not advise anyone who is in the beginning stages of learning to tune, to decrease the kr sensitivity tables. this forum will guide you in using the more sophisticated and accurate method of tuning, for now it's important that you get rid of kr. in the future, it's a good idea for you to get a w/b. the last subject i would like to mention is that the weight of a vehicle affects timing strategy, a heavier vehicle will require a little less timing than a lighter one,[ truck vs corvette]. if you could post your current tune i would be glad to review it. good luck either way.
    04 gto 243 gmpp cnc ported heads , hot cam 219/228 .525 112, kooks 1 7/8 l/t,lm-1wb, sending unit for fuel press. logging, drag bags for the track na 12.2@112mph 1.77 60ft. new add ons 42lbs lucas injectors, lpe walboro, daves wet plate kit, purge,heater, fpss, wot sw., fjo mini controller,nano, new p/b on hoosier 275/40/17 10.998@126.49mph,1.588 on 103vp, 18* timing 11.2 afr. n150w bassani catbk. catless with ls7clutch.

  5. #5
    Lifetime Member Doc's Avatar
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    What other mods do you have to the truck besides the heads? Exhaust? How many miles are on the truck? Cats/No Cats? Plugs?

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    Quote Originally Posted by jetblast View Post
    your strategy for combating kr and the lack of fuel is fine, for now. i'm assuming that you are using 93oct fuel, anything less is not adequate for the mods you posted. o2 values of less than .900mv is not good enough. since you do not have a w/b, it's ok if you just tune to .915mv using the nb o2 sensors, .920mv to or higher is probably too rich. wot tuning takes place on the last 1/3 of the entire load colums of the ve table, so 2.5% encrease is a good target. the maf table is way too high, instead, try 2% encrease from 8khz to the top. take the stock high oct. timing table and subtract 2* deg from .44gm/cyl to .120 or what ever the max is on your table and 3200 to max rpm colums. the last log that you posted seems that too much timing was removed. make a wot run with these settings, and report back. the other area that needs tuning with your mods is the low to midium load areas, which is indicative of the large positive ltfts, add 4% to the ve table in those areas, but do not touch the idle area, which is the 400 to 800rpm colums. i would not advise anyone who is in the beginning stages of learning to tune, to decrease the kr sensitivity tables. this forum will guide you in using the more sophisticated and accurate method of tuning, for now it's important that you get rid of kr. in the future, it's a good idea for you to get a w/b. the last subject i would like to mention is that the weight of a vehicle affects timing strategy, a heavier vehicle will require a little less timing than a lighter one,[ truck vs corvette]. if you could post your current tune i would be glad to review it. good luck either way.
    I greatly appreciate your input and help. I am attaching the current tune (blackGMCtune) and the original base tune which was a stock GM 2002 LQ4 tune. Indeed I am using 93 octane.
    Attached Files Attached Files
    Last edited by GMCtrk; August 16th, 2009 at 06:14 AM.

  7. #7
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    Quote Originally Posted by Doc View Post
    What other mods do you have to the truck besides the heads? Exhaust? How many miles are on the truck? Cats/No Cats? Plugs?
    Just 4.10s and a trutrac limited slip out back. Everything else is stock down to the air filter. I actually just finally ordered a CAI.

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    Quote Originally Posted by jetblast View Post
    your strategy for combating kr and the lack of fuel is fine, for now. i'm assuming that you are using 93oct fuel, anything less is not adequate for the mods you posted. o2 values of less than .900mv is not good enough. since you do not have a w/b, it's ok if you just tune to .915mv using the nb o2 sensors, .920mv to or higher is probably too rich. wot tuning takes place on the last 1/3 of the entire load colums of the ve table, so 2.5% encrease is a good target. the maf table is way too high, instead, try 2% encrease from 8khz to the top. take the stock high oct. timing table and subtract 2* deg from .44gm/cyl to .120 or what ever the max is on your table and 3200 to max rpm colums. the last log that you posted seems that too much timing was removed. make a wot run with these settings, and report back. the other area that needs tuning with your mods is the low to midium load areas, which is indicative of the large positive ltfts, add 4% to the ve table in those areas, but do not touch the idle area, which is the 400 to 800rpm colums. i would not advise anyone who is in the beginning stages of learning to tune, to decrease the kr sensitivity tables. this forum will guide you in using the more sophisticated and accurate method of tuning, for now it's important that you get rid of kr. in the future, it's a good idea for you to get a w/b. the last subject i would like to mention is that the weight of a vehicle affects timing strategy, a heavier vehicle will require a little less timing than a lighter one,[ truck vs corvette]. if you could post your current tune i would be glad to review it. good luck either way.
    Ok, here is the tune with the suggested changes you have recommended
    Attached Files Attached Files

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    Just took a log, looks like those changes made me go lean again and still knock.
    Attached Files Attached Files

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    that's ok, revert back and do 4% to the ve from 13.8 to 15.2 and select the linear blend feature, select blend colums only and encrease max blending. revert back add 4% from 8khz to 12khz. the mv o2 sensor values are still lean with the previous 2% and 2%addition of fuel. you want to contnue this balanced strategy until you get the desired .915mv, don't do anything more to the timing, it looks fine under the last wot run you made. once you get the .915mv you should not have anymore kr. and if in fact you don't have anymore kr then add timing 1* at time until you see kr, then back off 2*. this is just a ballpark figure, and in colder air you may need to back off a tad more. the w/b will tell you more accurately were your target afr should be. 12.8afr is my personal choice. make another run with the added 8% total fuel addition and post the run.
    04 gto 243 gmpp cnc ported heads , hot cam 219/228 .525 112, kooks 1 7/8 l/t,lm-1wb, sending unit for fuel press. logging, drag bags for the track na 12.2@112mph 1.77 60ft. new add ons 42lbs lucas injectors, lpe walboro, daves wet plate kit, purge,heater, fpss, wot sw., fjo mini controller,nano, new p/b on hoosier 275/40/17 10.998@126.49mph,1.588 on 103vp, 18* timing 11.2 afr. n150w bassani catbk. catless with ls7clutch.

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