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Thread: Negative Idle Timing.

  1. #41
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    ha you have asked that before and I cant come up with a good answer yet. It has to use that on a calc or something. I have no good answer, which is surprising since I have dealt with a lot of this.

    OP, so the problem just happened right? Out of nowhere?

    I would suspect a leak or a jump in a tooth, something like that. How many miles on the injectors? Fuel filter?
    Last edited by HNRClothing; 04-11-2012 at 04:40 PM.

  2. #42
    I don't exactly know when it started. I went out awhile ago to adjust my fuel trims, it was a pain in the ass and my exhaust was to loud. Tossed her up on the lift and bam there was a hole in the flex pipe, which was making my wideband off of course =D. So I replaced the flex pipe, exhaust sounds perfect thought all was good. Started dialing everything in and bam, noticed my timing at idle was negative.

    I have looked through past logs and haven't seen negative timing but these are like 6-8 month old logs.

    The injectors are fairly new, less than a year for sure. Not 100% sure on the exact date though. Fuel filter was changed out roughly 20k miles ago. Was just talking about changing it out again yesterday lol.

    If you couldn't see the numbers you would think the car was idling perfect, but we know it's not. I will play with the scalar and see if that helps. Thanks guys.

  3. #43
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    That is why it goes negative, so it idles good.

  4. #44
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    I am not an expert tuner by any means but i work at a gm dealer and most 4 cylinders idle at 3.5 g/sec min on airflow. also i have seen v8 cars idle to high because of the idle airflow being set to high but my editor doesn't show any way to adjust idle airflow on your car. so if your car idles on the ve table i would lower the ve in the part where it idles and see if that helps.

  5. #45
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    This may be completely dumb, but have you tried flashing back to the original file you received with your TVS? I understand you are running a smaller pulley but possibly getting rid of any changes that you may have applied that are causing issues. If you flash back and dont have issues, then you can do a comparison with your current file make changes one part at a time until your problem shows up again. Then bingo you know where to start making changes.

    now again that may be completely useless but when Im having issues with something i go over it change by change and see where the issue manifests

    Vaughn, your issue will be easier to fix when your car is back up and running and we can do some logs collectively and see what we can figure out, Ill check your file against a few things I have and see if I can see anything.

    Chris, Ill text you tomorrow, I think I found a dead spot in my PE where the car is seriously not happy. Ill try to get a log and send it your way, I need to get you a log of my idle as well lol, Im gonna be keeping you busy for a lil bit until IFO passes at the end of the month. I have some hondas that I want to beat up on.
    Last edited by eklipskid69; 04-12-2012 at 04:34 AM.

  6. #46
    Advanced Tuner laser_racer'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.
    Timing on the top on that tune is only at 17 degrees. Also on the tune I just set the afr to 10.0 and call it a day. Once the blend starts to change I just retune the maf I did mess with the stoich value before but just set it back and fixed tune.

  7. #47
    eklipskid69 - a tune isn't provided when you buy the TVS. I have always done all of my own tuning on my vehicle. I can upload 30 different tunes, stage 2 files, my own files, anything I want. The issue is ALWAYS there.

    Something I have noticed though is I am not moving as much air as I used to. I used to push over 40lbs per min on the maf side. I just saw 33 when I did a pull tonight.

    I did see a dent in my cold air intake so I am going to pull that and make sure it's a dent and not a gash that went all the way through it. If un metered air was escaping from the intake I am sure that would cause an issue, however I don't know if the gash/dent is that deep or what.

    Either way this is really annoying to track down. I have dialed in my maf and have used different injector settings to no avail. Somewhere though there is an issue because I should be moving more air through my maf then this.

    PS: Does timing have to do with how much air goes through the maf? IE more timing = more airflow or no??

    Edit: For the hell of it I might try switching to VE only instead of maf, just for idle, see if it changes anything.
    Last edited by 06cobaltss/sc; 04-13-2012 at 11:44 PM.

  8. #48
    Advanced Tuner Japeatr's Avatar
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    if it was a leak, would it not throw PO171?

    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

  9. #49
    Advanced Tuner laser_racer's Avatar
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    Not if you are tuning cause you will keep adding fuel to fix the vac leak. You may run in to a high idle service code the car will start to act like its in limp mode.

  10. #50
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    OP did you try to up the scaler to 4000 and see what it does? You will then need to play with the coastdown so the idle doesnt fall on its face in coastdown but it "should" help with the negative.

  11. #51
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    I am still saying there is a possibility that you jumped a tooth on the timing chain.

  12. #52
    If it was a jumped tooth, wouldn't it have issues 24/7 and not just from 140 degrees on up?

    I will try the scaler tonight in a few hours

  13. #53
    Advanced Tuner Japeatr's Avatar
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    its tune related. try Laser_racer injector setting and report back.

    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. #54
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    I thought he already tried them?

  15. #55
    I have tried A TON of different injector settings. Did you really fix the problem Japeatr or are you just pulling my strings here lol.

    I will double check and specifically try his settings again, along with the scaler right now.

    On a side note my battery crapped out on me. Something internally with the battery was draining itself out. Damn optima redtop. So I decided to buy an optima blue top 280$ battery, got it 3months old for 50 bucks! BAM. 100% perfect condition. Tossed my red top on a slow amp charger and will check it in a week, see if I cant make it come alive again.

    Either way, will update my findings tonight.

  16. #56
    In the car logging in my drive way right now. ECT is under 140 degrees and the timing is spot on where it should be. Fuel trims are off but I will deal with that in a bit. Rpm is also what I am commanding. 120ect everything is exactly the same. Letting the car warm up, said a quick prayer and so far everything sounds good. Were at 136 ect...getting closer...138 still good, and bam I can hear it change. Once again right at 140 ECT the rpms jump up 50-75 give or take and the timing is now 0 to -4.

    What is so special about 140 degrees that could be causing this..

    Edit - changing the scaler to 4k now, seeing if it helps. I think it has something to do with the o2 sensors personally. Isn't 140 degrees close to the point where it switches between the 2 loops?
    Last edited by 06cobaltss/sc; 04-25-2012 at 12:40 AM.

  17. #57
    OK this is new! I just changed the scaler, flashed it and all is well on the first start!

    Temp is 176 ect fuel trims are still off, but the car sounds like its idling well and visually my timing and rpms are what i am commanding.

    WHY do I need to adjust my scalar suddenly? What changed? After more logging here at idle it seems like my timing is all positive, but still fluctuating a bit. I will see if its due to fuel trims or not. Either way, the idle did improve with the scalar!

    Edit: I was reading on the forums and they said the throttle body had an orange gasket. That was an "oh shit moment" because I didn't remember seeing one when I pulled it off last. So I pulled it off again tonight and the TVS has a black gasket that is in there really tight and well sealed, no way it can easily fall out. HOWEVER as I was reinstalling the throttle body one of the bolts broke in half....It seriously wasn't even tight, barely any pressure and the cheap little bolt broke in half. Hopefully I will be able to get it out easily, but it just depends.
    Last edited by 06cobaltss/sc; 04-25-2012 at 02:14 AM.

  18. #58
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    I literally have no idea what/why the scaler helps. I dont know if it is a calc or something that it uses and helps with the airflow at idle.

    If you dont find anything that helps other than the scaler and you keep it, I would suggest changing your Coastdown Timing Table so when you go in neutral and let off the gas it doesnt want to fall on its face. Icrease the timing and you should be good.

  19. #59
    Ya I believe by default my coastdown was at 22 degrees. I also want to up my dfco timing because that was at 6 degrees and as soon as I hop back on the throttle im in the 25s to 30s and there is a bit of a surge, but thats easily fixable.

    Within the next day or two I should be able to have the majority of everything worked out. I will get a log up.

    I have a long trip, about 6k miles round trip coming up in a month so I am switching to regular 91-93 pump gas and tuning it to that. I will update this thread in a day or two and get a new log and some more info in here. Thanks again for the help guys and I will let ya know how it all works out!

  20. #60
    Senior Tuner cobaltssoverbooster's Avatar
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    so the idle etc scaler is being used in the idle airflow formula and if its off the ecu corrects it by removing or adding unneeded timing?

    if thats true when you change to le5 tb you increse it until the timing stops acting up and you have the proper etc area scaler value?
    2000 Ford Mustang - Top Sportsman