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Thread: Negative Idle Timing.

  1. #21
    I changed the overspeed and underspeed tables to zero.

    Below 140 degrees ect timing is ok, above that and it goes negative.

    I am trying different injector data to see if that helps, which means I have to redo the maf completely so this is going to take some time.

    I can't figure out why the car would idle faster than I am commanding randomly. It makes no sense that while warming up the car is idling just fine at whatever I command, and then randomly bam it decides to idle 1k higher. No clue why... and it starts this at exactly 140 degrees ect, just checked a little bit ago again.

  2. #22
    Advanced Tuner gn2beatu's Avatar
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    I agree with wyochimneysweep, and what I said earlier. Its the idle air gap. Its getting too much air, and trying to lower the idle with spark retard. Just cause the TB works on another car, doesnt mean it will for you.

    How big is the air gap between the blade and the housing. Can you see a big crack if you hold it up to the light? You could always do a simple and easy test to see if the throttle blade gap is too big. If the gap is too big, put a piece of tape on one side of the TB housing right where the blade makes contact. (one side only) See if the Idle speed then drops to the 850 you want. If it does, the air gap is too big. Its a quick test.
    2000 Regal GS ~ 3.25 Pulley ~ Headers ~ 3"ex ~ 1.85 Rockers
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  3. #23
    Here is an update.......I am thinking there is a leak somewhere because I have a TVS with a pretty small pulley, and I am not boosting at 1.36 cyl air mass which I am pretty sure is where I was at before. I am going to go over everything and see what I can find. Will let ya know if thats what is causing the issue or not.

  4. #24
    Advanced Tuner Japeatr's Avatar
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    i am having the same issue on mine. CLOSED LOOP causes negative timing at idle.

    See log and tune ...log shows neg or very low timing at idle from 13:40.xx - 14:24.xx

    please help me find this idle overspeed issue/table on my tune!~~~

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  5. #25
    Advanced Tuner laser_racer's Avatar
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    I bet its actually bad boost leak from either injector insulators orings, injector orings, or a sensor is not sealed good.

  6. #26
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    ^ That is a good call. I just had a customer with an idle issue. I pulled the injectors and had them tested and the seals were bad along with the injectors had inconsistant flows at idle. Pull the injectors and go to ACE or some store like it and get new o-rings for the injectors and the caps. Cheap and could reduce or eliminate the issue. If you want to test it first get some vacuum grease and coat the o-rings.

  7. #27
    Japeatr - I haven't been able to look over your tune yet, but I do have a question. What is your cyl air mass at wide open throttle?

    I am pretty sure mine has always been 1.36 whenever I am wot with my TVS. I forget what size pulley I have but I am 99% sure it's always been 1.36 and now it's not. Somewhere there is a leak, but the car drives perfectly and the fuel trims are within reason while driving too.

    Only other thing I noticed with the car was that it "seems" like my boost gauge is reading lower when I am in dfco then usual. Example I idle at roughly -20 on my boost gauge and usually when dfco hits i am like -23 give or take. Now I am like -25 to -27, damn near maxing out the gauge.

    Pretty sure there is a leak somewhere but I have no idea where. Wish me luck finding it guys.

    Japeatr - as soon as I get the new hptuner beta on this desktop I will take a look at your tune.

  8. #28
    Senior Tuner cobaltssoverbooster's Avatar
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    wouldnt a leak make more positive vacuum because its letting air in.....
    your mass vacumm would be more along the lines of something is sealing off somwhere and starving the engine of air thus giving you a higher vacuum value, but please if im wrong teach me 8)

    i have seen people put a scratch in the supercharger seal causing a minor airleak that has effects after idle but the ammount leaking past at idle is so little that it is caught by the idle airflow adjustments performed by the ecu. but since the injectors have to come off first as stated it would be the best spot to start.
    all boost pressure issue are at the blower or after so youd be looking at:
    -fuel injector seals
    -recirculation valve-for a hole or not sealing properly because of damage or spring creep? i havent had one appart to know if it has a spring
    -supercharger flange gaskets
    -intake manifold gasket
    am i correct?
    2000 Ford Mustang - Top Sportsman

  9. #29
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    head gasket/bolts (lifted head) but I would think it would show signs of that. i.e. coolant/oil leak or mixing.

  10. #30
    Advanced Tuner Japeatr's Avatar
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    i firmly beliwve it is an overspeed issue, not a vacuum leak

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  11. #31
    Advanced Tuner Japeatr's Avatar
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    hey. check you map sensor connection from having to modify for TVS install.

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  12. #32
    Senior Tuner cobaltssoverbooster's Avatar
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    ^do you have to extend the harness for the tvs? the one i saw was already done when i saw it.
    2000 Ford Mustang - Top Sportsman

  13. #33
    Advanced Tuner Japeatr's Avatar
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    no the MAP sensor mounting hole has to be cust off so it can rotate 45deg

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  14. #34
    Senior Tuner cobaltssoverbooster's Avatar
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    ohhh ok i see now. after that i looked at before and afters and makes sense now. thanks.
    2000 Ford Mustang - Top Sportsman

  15. #35
    Advanced Tuner laser_racer's Avatar
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    Quote Originally Posted by Japeatr View Post
    i am having the same issue on mine. CLOSED LOOP causes negative timing at idle.

    See log and tune ...log shows neg or very low timing at idle from 13:40.xx - 14:24.xx

    please help me find this idle overspeed issue/table on my tune!~~~
    How come your spark smooth table is disabled? You can give these 80 settings a try and you can give that idle timing table a go, but anytime I ever had a bad negative idling problem I had vac leak. You won't loose any vac on the gauge because the throttle body is slammed shut trying to hold idle. Try idling the car down below 900 and you will most likely throw a high idle code then the car will start to spit and studder just fyi you most likely won't see the code cause it takes two throws to show up.

  16. #36
    laser - I take it that was an e85 tune lol. Your timing on the wot side of that tune is just crazy...hope it's not accurate lol. Your injector settings match mine pretty closely, I will copy and paste them in and give them a shot. I know your short pulse adders were slightly different but not massively.

    Either way, still trying to track down what would cause this. At least the car still runs great and drives great and everything besides idle is fine.

    Another random thing to toss in for you guys is if I toss the car into neutral and coast to a stop, right when I am stopped, the car idles like it should. Then about 5 seconds later it changes and the idles negative. It's odd I tell ya.

  17. #37
    Advanced Tuner Japeatr's Avatar
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    Kendall, your hpt file you posted has stoich at 10.0:1. mine is at 9.799.

    Were you adjusting for seasonal blends? Just Curious

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  18. #38
    Advanced Tuner Japeatr's Avatar
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    Quote Originally Posted by 06cobaltss/sc View Post
    laser - I take it that was an e85 tune lol. Your timing on the wot side of that tune is just crazy...hope it's not accurate lol. Your injector settings match mine pretty closely, I will copy and paste them in and give them a shot. I know your short pulse adders were slightly different but not massively.

    Either way, still trying to track down what would cause this. At least the car still runs great and drives great and everything besides idle is fine.

    Another random thing to toss in for you guys is if I toss the car into neutral and coast to a stop, right when I am stopped, the car idles like it should. Then about 5 seconds later it changes and the idles negative. It's odd I tell ya.
    same behavior

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header

  19. #39
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    Quote Originally Posted by 06cobaltss/sc View Post
    Another random thing to toss in for you guys is if I toss the car into neutral and coast to a stop, right when I am stopped, the car idles like it should. Then about 5 seconds later it changes and the idles negative. It's odd I tell ya.
    That is because it start to look at the over/under speed timing tables is my guess.

    Increase the idle scaler to like 4000 and see what that does. I have seen that decrease or eliminate negative idle timing.

  20. #40
    Advanced Tuner Japeatr's Avatar
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    HNR good point, but why would the scaler effect it??

    384whp/303wtq
    Built 2.0LSJ: TVS w/2.6, 1000cc, Stage 2 cams, custom fuel system, E85, Dual Pass, 3"intake, 3" Catless exhaust, CIA midlength Header