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Thread: Advice on timing for Lq4 - noobie

  1. #1

    Advice on timing for Lq4 - noobie

    Hi guys

    2003 LQ4/4L80e/4.10, bone stock with LS1 intake, shorty headers & CAI

    I just got my Lq4 Cherokee on the road. I'm new to HPT but have done a lot of reading.

    Right now I'm wanting to tweak the TM and timing. As it is this thing blows away the tires in 1st and most of 2nd. I'd like to use TM to reduce the torque in 1st & 2nd in hopes it will hook up.
    Also, I'd like to be a little more aggressive with the timing. The LQ4 came out of a 3/4 ton truck with a GVW in excess of 10,000 lbs. I wish to continue using 87 octane because is so expensive. I see no knock activity in my log. the truck is around 3300 lbs with 4.10 rear. It engine does not work to make this thing move. Cooling system maintains 87* C in 30* ambient.

    If some kind person would view my files and make a suggestion as to the TM & timing I would greatly appreciate it.

    Thanks,
    Richard
    Attached Files Attached Files
    Last edited by LS XJ; 07-26-2017 at 05:48 PM.
    ~ Richard ~
    1992 Jeep XJ - Gen3 - 6.0LS, 4L80e, 4.10, 2wd

  2. #2
    Tuning Addict 5FDP's Avatar
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    I don't see the knock retard channel being logged, so not really sure how you'd know if it was knocking. Add knock retard, injector pulse width and commanded AFR to your logs.

    87 is going to limit you alot, run at least 89 to get away with a little more timing.

    You really need to work on your fueling tables first before adjusting timing. The computer is having to add a ton of fuel at part throttle and full throttle, just look at your trims. The LS1 intake is much smaller than a truck intake and the headers are also changing the airflow of the motor, so the factory MAF curve and VE table are wrong now.

    Low to mid 20's on timing is great for power on a 6.0, no real reason to try and max it out. The juice isn't worth the squeeze.

    For TM you can try and limit the torque in 1st gear, it's currently set to 640, maybe go half that at 300 and see if it helps any but without a real traction control system it can only do so much. You may need to invest in some sticky tires to get the power down too.

    Other helpful tips, In the PE tab change the RPM delay for PE down to 2,000 rpm compared to 5,500. Remove the 60 second time delay as well. Lower the pedal % from 90% to 70% and lower the enable torque value to 80%. These settings will make sure that once you do start WOT tuning that you will have fuel there when you need it.

    Switch to advanced view if you haven't too, edit > view > advanced so you can see all tables.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
    I thought that if I saw KR on the timeline graphing it was logging it. I figured out how to add that channel now.

    Now I'll work on the VE table.

    Thanks for the help.
    ~ Richard ~
    1992 Jeep XJ - Gen3 - 6.0LS, 4L80e, 4.10, 2wd

  4. #4
    I've upped my fuel pressure reg to 60 psi with vacuum hose connected.
    I've topped up the tank with 89
    I logged a WOT, file attached.

    I don't have a wide band yet. Do my WOT logs really show where I need to work on my VE seeing as I only have the narrow band O2s?
    At this point I'm just wanting to have a safe tune. I plan on taking it to the track tomorrow and I'd like to be able to drive it home afterwards!

    I set the TM to 300 from the 640 as suggested. No throttle. So I changed it back. It is odd that the 300 I entered was not accepted as a valid value. It says 0-640 is valid.

    I think the WOT file looks better now.

    Thanks
    Attached Files Attached Files
    ~ Richard ~
    1992 Jeep XJ - Gen3 - 6.0LS, 4L80e, 4.10, 2wd

  5. #5
    Tuning Addict 5FDP's Avatar
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    I would not take it to the track, you still haven't tuned the MAF or VE. Going WOT or beating on it is just asking for possible trouble.

    Look at your fuel trims, just at a normal idle and cruising it's trying it's hardest to add anywhere from 10-25% worth of fuel if not more. The value stops at 25, so it could even be higher than that. Overall your fueling is whacked at best and not something you should be testing the waters with. Breaking stuff at stock power levels is harder but continued abuse on a non-tuned motor could spell disaster.

    You also didn't change the PE to help make it safer, it's not entering Power Enrichment until 3/4 into that WOT pull. I'd even adjust the PE eq ratio to 1.210 from 3500-6000+ to keep the commanded AFR at 12.0-12.1 and save yourself some injector headroom. It was going up towards 95%, around 88-90% is the highest you'd like to see. Though things may change slightly as you get the fueling dialed in.

    For a start anyway you could add 5% to the lower regions on the VE and add a touch of fuel to the MAF curve to get the trims lowered. In the VCM scanner section there are helpful threads on tuning the VE or MAF with the fuel trims to get you in the ball park until your wideband arrives.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  6. #6
    Thanks for looking at the file and I do appreciate your help. I'm not new to automotive, just new to this tuning, so I'll be trying your patience with all my noobie questions.

    Looking at the log file, where do I look to determine when it entered PE? So many things on the screen, just a wee bit of help needed.

    After this pull I did set the PE delay to zero and the RPM to 4500. With the low gears this thing isn't even working to move it so I didn't think I needed PE below 4500.

    As far as dialing in the VE, please excuse my ignorance, but do I just view the log file, determine what RPM and MAP points the Fuel Trim is off and by what percent, and then use the editor and make adjustments to the VE at the same RPM & MAP points?

    I'll need to figure out how to smooth the transition to the surrounding cells. I'm still trying to find a good video on Youtube that clearly shows the highlighting and what table options I should use.


    Thanks again for your help.
    ~ Richard ~
    1992 Jeep XJ - Gen3 - 6.0LS, 4L80e, 4.10, 2wd

  7. #7
    So I'm not clear on the LTFT. I know what fuel trims are, a deviation in percent from the VE that the PCM has to make to keep the AF where commanded. A plus is the PCM adding fuel, a minus is the PCM removing fuel.
    The LTFT I have always thought was an average trend over time, kind of like your average MPG vs your instant MPG. So I would not expect to see the LTFT change quickly if the history is not brief and the STFT are low and pretty steady.

    I've posted a log of the truck driving easy up a fairly steep hill. Gentle throttle, RPM around 2000.
    The STFT although not perfect is single digit and stays near zero mostly. The LTFT also stays near zero.
    Both this log and the WOT I posted earlier were done within 30 minutes with no tuning.

    Question
    Why is the LTFT looking good on this log but not the one I posted above.

    Thanks
    Attached Files Attached Files
    ~ Richard ~
    1992 Jeep XJ - Gen3 - 6.0LS, 4L80e, 4.10, 2wd