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Thread: Cammed C7 idles but has negative timing. 3 bar map sensor seems to be reading high

  1. #21
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    stock tb. I had the maf set in another tune but it didn't effect the idle. I'll try the throttle cleaned button. Can't hurt right.

  2. #22
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    Idle just stuck up above 1200 rpm. When I blipped the throttle it stayed there too. Do I need a baro breakout? I figure it would help but this car doesn't want to come close to running right. Something physical must be wrong. Maybe a vacuum leak or something? Funny thing was it was running better before we put the 3 bar in it. I remember it was idling solid (sounded awesome) but I tapped the gas and it got stuck around 2k and we got a cel for the map sensor. So I figure let's toss in the 3 bar now. Since then I've been fighting it

  3. #23
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    I posted a response that I somehow deleted when I went to edit a typo...

    Anyhow if it's NA just leave a 1 bar in it.

    Messing with min timing, virtual torque the wrong way or DD the wrong way can cause throttle hang.

    This can be fleshed out more but the gist of fixing low timing if the airmodel is correct is to change virtual torque increments to 5 and minimum to be less than where it's idling, then take torque out of the negative and low timing areas until it brings the spark up to meet torque vs using the tb, but definitely fix fueling first.

    Negative idle timing sounds bad and causes glowing headers. People need to learn to fix this, but step one is getting the air models correct for sure.

  4. #24
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    It's not N/A its' got a YSI Vortech blower on it too. I think something might be effecting the way it's running. The car said it was running very lean but the map was way to high for idle. I've brought the maf in check but it still seems to be off. Any tricks/tips for tuning the VE? When I zero out the maf to tune the Ve the car goes into limp mode.

  5. #25
    Senior Tuner SultanHassanMasTuning's Avatar
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    without breakout for baro, you will have your P ratio off
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  6. #26
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    Definitely need breakout on a centri car.

  7. #27
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    I ordered the break out

  8. #28
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    No one wants to say what they do to put the car in ve only? How are you guys turning off the maf without running into limp mode on the gen V stuff?

  9. #29
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    Quote Originally Posted by JASON11WS6 View Post
    No one wants to say what they do to put the car in ve only? How are you guys turning off the maf without running into limp mode on the gen V stuff?
    I have honestly never experienced what you are experiencing.

    Fail maf with hz, mil on 1st for 0101-103, set dynamic to 8192 8190 and that's it.

  10. #30
    Senior Tuner SultanHassanMasTuning's Avatar
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    Quote Originally Posted by JASON11WS6 View Post
    No one wants to say what they do to put the car in ve only? How are you guys turning off the maf without running into limp mode on the gen V stuff?
    doesnt matter as even with SD mode your calculation will be off because of baro
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  11. #31
    Advanced Tuner lt1z350's Avatar
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    sort of going through this myself as just did a cam and heads on my lt4. I found that I had to mess with vt just to get the timing around 0 and headers not to start glowing. cooked a gasket quickly so now think its flooding that side with fresh air on the o2. Here is what I had been seeing. I get it to decent timing 6-8 degrees then it wants to go lean. So then add back to the maf or vve and timing drops as airmass goes back up. Correct one thing then it sets off something else. Cam is bigger then his 227/244 but has -.05 overlap so the idle is very tame and have dropped it to 700 now trying to see how that affects it from 750. Its like fix one thing affects the next then throws it back off. Is it best to start with vve and not worry about where the timing is currently?
    And yes tuning school is shit when comes to heads and cam I did get a tip from someone about starting with the greg banish gen v at detroit technical media and some really good stuff in that 200 dollar on line video. Its now trying to look at the logs to figure out how adjust the idle settings to what your seeing. There is no way to patch this like older stuff like raising min timing tables as it will start to fluxuate as you took timing off the table to make idle stable.
    I feel like on mine the fact fixing one causes another thing to go out of wack and it snowballs quickly. kpa goes up then fuel pressure goes up then gets more rich on the same vve and maf anytime airmass changes at all things go away from what you just fixed. So i guess finding the correct starting point here is really important. I was going to start a thread then saw this so hope we can help each other here. I have a good understaning of alot of it but hard to work out when it keeps changing so much with one changed table
    First 9 second 6th gen lt4 zl1 stock blower SHC SBE boost only.

    2013 cadillac ats 2.0t Big turbo-gone
    2007 tahoe 5.3 lsa blower on 14 lbs boost 6l80e swap 2009 os
    2017 zl1 a10 big gulp/2 inch headers/ 9.55 lower/ e85/bigger hx /103mm tb / Synergy trunk tank and underhood kit/methanol injection with torqbyte controller and prometh pump / Jokerz performance R&D ported stock blower/ lme cnc heads /GP tuning custom cam. So far 9.30@150

  12. #32
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    Quote Originally Posted by lt1z350 View Post
    sort of going through this myself as just did a cam and heads on my lt4. I found that I had to mess with vt just to get the timing around 0 and headers not to start glowing. cooked a gasket quickly so now think its flooding that side with fresh air on the o2. Here is what I had been seeing. I get it to decent timing 6-8 degrees then it wants to go lean. So then add back to the maf or vve and timing drops as airmass goes back up. Correct one thing then it sets off something else. Cam is bigger then his 227/244 but has -.05 overlap so the idle is very tame and have dropped it to 700 now trying to see how that affects it from 750. Its like fix one thing affects the next then throws it back off. Is it best to start with vve and not worry about where the timing is currently?
    And yes tuning school is shit when comes to heads and cam I did get a tip from someone about starting with the greg banish gen v at detroit technical media and some really good stuff in that 200 dollar on line video. Its now trying to look at the logs to figure out how adjust the idle settings to what your seeing. There is no way to patch this like older stuff like raising min timing tables as it will start to fluxuate as you took timing off the table to make idle stable.
    I feel like on mine the fact fixing one causes another thing to go out of wack and it snowballs quickly. kpa goes up then fuel pressure goes up then gets more rich on the same vve and maf anytime airmass changes at all things go away from what you just fixed. So i guess finding the correct starting point here is really important. I was going to start a thread then saw this so hope we can help each other here. I have a good understaning of alot of it but hard to work out when it keeps changing so much with one changed table

    I always start with air unless timing is way off and will cause a glowing header situation while I'm trying to get the air in shape. I would start with stock VT tables though, and only mess with the idle rpms and blend it up to 2400 or so to get it in the ballpark while you are figuring out what air it wants.

    You can have two identical cars with identical mods and one will want to idle with -10 timing whereas the other will act normal.

  13. #33
    Advanced Tuner lt1z350's Avatar
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    Quote Originally Posted by sevinn View Post
    I always start with air unless timing is way off and will cause a glowing header situation while I'm trying to get the air in shape. I would start with stock VT tables though, and only mess with the idle rpms and blend it up to 2400 or so to get it in the ballpark while you are figuring out what air it wants.

    You can have two identical cars with identical mods and one will want to idle with -10 timing whereas the other will act normal.
    gotcah will do as I was trying to use a vve table from a car with like you said similar mods and a cam that was very close to mine. I actually tried 3 different cam vve tables I had from verious tuners just to see if one was in the ball park. Funny thing was a stock lt5 vve prior to the cam was working great in my attempts to get the vve setup well on the bolt on stuff. seems these stock ported 1.7 ltr blowers flow closer to a 2650 then stock blower at idle to part throttle anyway. I had only got to around 3500 rpm tuned when tore the car down and did the cam and lme heads. But I had found the radicaly different lt5 vve was only off by -7 all the way into 3500 range vrs the stock table that was way too lean. but going back to the stock table so see where it falls and will start with your advice.
    One more thing from you guys when doing vve with maf disabled are you still seeing it log maf hz on the log? I was still seeing it so I cut the green and white wire when was doing it before as wasnt sure if that is actually affectiing the vve or not. Yes it was a pain but I was just experimenting and you cant just unplug it. Seems these gen v dont fail quite the same on zl1 vrs other e92 and some can go right into reduced power too. I found cutting the wire it didnt do that when all errors were set to not report.
    Thanks
    First 9 second 6th gen lt4 zl1 stock blower SHC SBE boost only.

    2013 cadillac ats 2.0t Big turbo-gone
    2007 tahoe 5.3 lsa blower on 14 lbs boost 6l80e swap 2009 os
    2017 zl1 a10 big gulp/2 inch headers/ 9.55 lower/ e85/bigger hx /103mm tb / Synergy trunk tank and underhood kit/methanol injection with torqbyte controller and prometh pump / Jokerz performance R&D ported stock blower/ lme cnc heads /GP tuning custom cam. So far 9.30@150

  14. #34
    Senior Tuner eficalibrator's Avatar
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    Quote Originally Posted by lt1z350 View Post
    And yes tuning school is shit when comes to heads and cam I did get a tip from someone about starting with the greg banish gen v at detroit technical media and some really good stuff in that 200 dollar on line video. Its now trying to look at the logs to figure out how adjust the idle settings to what your seeing. There is no way to patch this like older stuff like raising min timing tables as it will start to fluxuate as you took timing off the table to make idle stable.
    If you only got the DVD from DTM, we made a few more GENV videos since then. Everything is hosted on our streaming site HERE now. Specifically, we made addendums to the torque model and idle control strategies for GENV with more information. This segments are available separately from the main GENV video so you don't need to "re-purchase" anything to get them.

    GENV idle is really a balance of torques, so getting it right requires that you have VVE, VT, and MBT all correct for your specific combination.

  15. #35
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    So I have the baro breakout on the car now and the car is still a nightmare. The ltft just keep saying to pull out of the VE tables. SO I keep going at it, 15-20% at a time. The timing is still way negative and it still wants to idle on the moon as soon as you touch the throttle. I'm going to keep at it but do you guys have any suggestions? Should I creep some out of the VTT at the idle areas? Should I take some out of the external idle table? Or should I be going in the other direction all together.

  16. #36
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    Quote Originally Posted by eficalibrator View Post
    If you only got the DVD from DTM, we made a few more GENV videos since then. Everything is hosted on our streaming site HERE now. Specifically, we made addendums to the torque model and idle control strategies for GENV with more information. This segments are available separately from the main GENV video so you don't need to "re-purchase" anything to get them.

    GENV idle is really a balance of torques, so getting it right requires that you have VVE, VT, and MBT all correct for your specific combination.
    Watched a couple videos from you guys. Good lessons but you didn't show how to execute much of it. Examples of which direction to go inspire confidence.

  17. #37
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    Switched the maf tuning to see how the car ran on the maf. Idle is bouncing and the ltft are saying its lean after being rich on the vt side. All my hair has been pulled out

  18. #38
    Senior Tuner SultanHassanMasTuning's Avatar
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    post your latest tune and also log and key on engine off log
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  19. #39
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    ysi.010.hptysi.010.hplysi.koeo.010.hpl


    Here is where I'm at. I keep pulling out the the VE because it was asking for it and the maf side wants me to add.

  20. #40
    Senior Tuner SultanHassanMasTuning's Avatar
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    any DTC
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