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Thread: cold start hunting with audio. suggestions to fix.

  1. #1
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    cold start hunting with audio. suggestions to fix.

    So I'm looking for suggestions to help with the startup. Engine starts fine but hunts a little for the first minute then will stabalize. VVE and MAF are tuned the best I can using the street and when its warmed up runs great.
    mods are BTR3 cam, 2.5 and 8.66 pulleys,nw103,catless LT,1200cc inj. ported 1.9L,cai, has flex but I have e10 in the tank.

    I tried uploading an mp3 and mp4 audio files but the forum said invalid file. I put a link in my youtube so you can hear as well as see the scan and tune. I stopped the scan after it stabalized to keep this short and easier to diagnose.

    Thanks to the forum and all your help with teaching me about calibrating.

    https://youtu.be/iIKFEpaI3Ps

    TEST COLD START IMPROVEMENT_WORKING TUNE_MAF ONLY.hpt

    11.22 COLD START W AUDIO.hpl

  2. #2
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    Looking at your timing table it looks like you have a zl1 (very similar to my ctsv). First, thing i notice is your idle spark is only 15 deg. (which is stock). You most likely need to bump that up a little bit. I also noticed right as you started it you are commanding an insanely rich afr (like 7:1). You actual afr seems pretty rich as well (9.5ish:1) I'd try and put your OL tables back to stock and do another cold start. You are already at stoic at an ect of 54 deg which seems too soon imo. One of the things that i discovered is if you match your "o2 readiness ect" (under "fuel" then "oxygen sensors" under "monitoring) with when your car goes into closed loop, your afr will follow your commanded much closer while in OL. You can see in your log that the o2s start to switch around 55 deg ect even though technically you shouldn't be in CL until 95 deg ect.

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    Quote Originally Posted by sgod1100 View Post
    Looking at your timing table it looks like you have a zl1 (very similar to my ctsv). First, thing i notice is your idle spark is only 15 deg. (which is stock). You most likely need to bump that up a little bit. I also noticed right as you started it you are commanding an insanely rich afr (like 7:1). You actual afr seems pretty rich as well (9.5ish:1) I'd try and put your OL tables back to stock and do another cold start. You are already at stoic at an ect of 54 deg which seems too soon imo. One of the things that i discovered is if you match your "o2 readiness ect" (under "fuel" then "oxygen sensors" under "monitoring) with when your car goes into closed loop, your afr will follow your commanded much closer while in OL. You can see in your log that the o2s start to switch around 55 deg ect even though technically you shouldn't be in CL until 95 deg ect.
    I might have the spark too much now, but I'll try it. It is a 2014 ZL1 so an E67 ecu.

    here's the new tune
    .
    .TEST COLD START IMPROVEMENT_WORKING TUNE_MAF ONLY_sgod1100.hpt

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    Quote Originally Posted by marksrig View Post
    I might have the spark too much now, but I'll try it. It is a 2014 ZL1 so an E67 ecu.

    here's the new tune
    .
    .TEST COLD START IMPROVEMENT_WORKING TUNE_MAF ONLY_sgod1100.hpt
    18 degrees isn't too much at all...especially since you have an aftermarket cam. also log idle desired airflow and minimum airflow. Your adaptive idle spark is going nuts trying to over correct (at least in my novice opinion)

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    Quote Originally Posted by sgod1100 View Post
    18 degrees isn't too much at all...especially since you have an aftermarket cam. also log idle desired airflow and minimum airflow. Your adaptive idle spark is going nuts trying to over correct (at least in my novice opinion)
    Yea my spark at idle jumps a lot, makes for a nice lope ha! I'll work on that but I want to try the other stuff you suggested before I get too far off what I'm wanting to do and that's get rid of the hunting at startup. The BTR3 cam doesn't have overlap. LSA is 120* the stock cam is 122* so a smooth idle is possible but I'm not sure if I want it. I like the shake.
    Thank you for the help. Now I wait for tyhe car to get cold again.

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    Quote Originally Posted by marksrig View Post
    Yea my spark at idle jumps a lot, makes for a nice lope ha! I'll work on that but I want to try the other stuff you suggested before I get too far off what I'm wanting to do and that's get rid of the hunting at startup. The BTR3 cam doesn't have overlap. LSA is 120* the stock cam is 122* so a smooth idle is possible but I'm not sure if I want it. I like the shake.
    Thank you for the help. Now I wait for tyhe car to get cold again.
    Sure, no problem...if you want to try and calm the shake down go to the "spark" tab, then under "idle adaptive spark control" multiply both the over and underspeed by tables by .5 (basically cutting them in half). That should help with the shake....if you want the shake INCREASE them...lol.

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    Quote Originally Posted by sgod1100 View Post
    18 degrees isn't too much at all...especially since you have an aftermarket cam. also log idle desired airflow and minimum airflow. Your adaptive idle spark is going nuts trying to over correct (at least in my novice opinion)
    So I tried the start before work today and the spark increase seems to have helped. The temps outside weren't as cold as the original log so I want to see during a freezing morning. As far as the super rich you were seeing at the start of the car, the wideband resets it's pre-checks as soon as the car starts and the hpt scanner is seeing a default. Once the wideband is online, the continued rich events are from the openloop tables that you referred to in the first post were basically stock. I noticed that at below 46*F for the ECT and IVT the EQ ratio was like 1.36 ( i'm at work and don't have the actual number) and then there was a gain table adding as well. I can trim these down a bit to help. I liked the idea of moving the O2 readiness off of the default -40* to something warmer to keep from going CL too fast.
    I'll post a start soon when we get a freezing morning again.

    Mark

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    Not the WB measured, he's talking about the AFR Commanded & EQ Ratio Commanded in that log. ~20 seconds after the engine fires it's still asking for 7.5:1/1.87 which is insane rich, if it's actually delivering that much.

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    OH yea, commanded is really rich. I'm adjusting the OL tables for the next startup.

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    Quote Originally Posted by blindsquirrel View Post
    Not the WB measured, he's talking about the AFR Commanded & EQ Ratio Commanded in that log. ~20 seconds after the engine fires it's still asking for 7.5:1/1.87 which is insane rich, if it's actually delivering that much.

    OK, well I didnt adjust enough apparently. still commanding rich and startup wasnt great. I'll make it command .85 for tomorrows test and see it it pays attention but in the mean time, here is the latest scan and tune.

    You can see once the WB EQ ratio shows change its in the 12.5:1 area so it's not following commanded. suprisingly it doesnt smell rich in the garage,


    TEST COLD START IMPROVEMENT_WORKING TUNE_MAF ONLY_sgod1100_altered openloop EQ.hpt

    11.24 cold start.hpl

  11. #11
    Tuning Addict blindsquirrel's Avatar
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    Yeah, actual and commanded will never match up on a cold engine since O2 sensors don't measure unburned fuel, which cold engines tend to have a lot of. That's why the mix needs to be rich when cold, because some amount of what gets put in can't be burned in the cylinder until heat builds up. Give it what it wants to run clean on cold start, do not try to adjust anything based on O2 readings because you are not seeing real data when it's cold.

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    ^^yup, in my experience ive had to adjust the OL IVT gain table to not have my car so lean during warm up/cold start. Actual af rarely matches commanded during this time but my drivability is much better while the car is warming up.

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    Quote Originally Posted by marksrig View Post
    So I tried the start before work today and the spark increase seems to have helped. The temps outside weren't as cold as the original log so I want to see during a freezing morning. As far as the super rich you were seeing at the start of the car, the wideband resets it's pre-checks as soon as the car starts and the hpt scanner is seeing a default. Once the wideband is online, the continued rich events are from the openloop tables that you referred to in the first post were basically stock. I noticed that at below 46*F for the ECT and IVT the EQ ratio was like 1.36 ( i'm at work and don't have the actual number) and then there was a gain table adding as well. I can trim these down a bit to help. I liked the idea of moving the O2 readiness off of the default -40* to something warmer to keep from going CL too fast.
    I'll post a start soon when we get a freezing morning again.

    Mark
    yeah, just adjust that o2 readiness to what ever ect temp you want your car to go into CL...ive had mine set at 133 degs with no issue at all. You will be able to see that with the o2 readiness set at your CL point they will not influence the a/f ratio during OL which is what I wanted. I noticed that a while as even though your are in OL the o2s were still doing some fuel trimming.