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Thread: Injector timing and transients

  1. #1

    Injector timing and transients

    Hey guys, hope alls well. Long story , short. 4.8 single turbo 228/230 cam. injector timing-THANKS FOR THE WORKSHEET! would someone take alook at what I came up with on the worksheet? Can this be right? the values are way off from factory! will these setting be beneficial to spooling turbo? next is transients- ive worked with these setting for a couple days and am having issues nailing it down. problem is lean tip in 5-10% then rich let off up to 15% then lean again then settles near lambda. weird right? the impact factor and evap tables, larger numbers subtract fuel or add fuel? IDK ive run myself into a huge circle. any advise would be much appreciated.
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  2. #2
    Advanced Tuner
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    I've been playing with these myself. There is a ton of math involved thats over my head but I can point you in the right direction.
    Impact Factor Gas: Smaller numbers will richen your lean tip in
    Evaporation Factor Gas: Larger numbers will richen tip out.
    I'm still trying to get this together and had some success but think the Intake Valve Temp is fouling me up.
    Everyone is welcome to correct me if I'm wrong,

  3. #3
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    with the transient fueling i look at a few areas the VE or VVE or MAF if ur using it and the wideband error during throttle stomps/decent movements, then cruse at a desired rpm steady state and then use some throttle movement and u should see if it tips in too lean/rich i adjust the transient fuel in that area or global for the given IVT row, if u get the latest beta version i noticed there are some added features and u now get a PE exit value so u could adjust that for any rich tip tip out so it leaves PE quicker if thats part of your issue, with the VE or VVE or MAF if u have those with some error like a hump or dip see if its where u are using the throttle and if it is u need more transient fuel in that area, i always smooth my VE as its dialled in for as close to steady state as can be for a street tune and if it has any lean/rich spots i watch throttle movement for that point and adjust the transients to compensate for it and u should find it fixes it up pretty good, can take a while tho as u have to juggle the VE, VVE, MAF with the transient fueling

    for the EOIT set the boundary to all 520 and the rpm all zero, the ect to 90 and leave the others, that should get u good and maby just a tweak to dial it in see what ur fuel error is at idle and lower the the 90 to 85 see if its richer or not if it is then all good if not try the other way back to 95 see what it does and then once done fix up the fuel error and its good to go, then if u want u can delay it more as rpm rise in the boundary table but just dont go too far as u can get reversion back out the intake at some cruise rpm's so 1500-2500 i usually setup for best cruise

  4. #4
    Thanks. impact factor- smaller numbers richen- that's probably what had me messed up. I was enlarging the numbers. is adjusting both impact and evap necessary? do either carry more weight? I did as you suggested and used map and intake valve temp to find percent of error and apply to each table, but which table takes precedent? injection timing- I looked at some factory boosted autos and saw they have 520 across, but they have values in the short pulse adder. mine does not after 0.8ms. should it? and does min pw come into play? I think mine is set at 0.8. what is a normal delay for upper rpms beyond 520? I'm going to work on this today if I don't have to work.

  5. #5
    I just saw something else- on transients the accel/decal ratio- on factory boosted apps this # is a lot lower than in this truck ecm. being turbo'd should I look into this (0.4 to 0.9 compared to 1.2).

  6. #6
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    I had to fix my rich after reflash before trying to tackle Transients.That said I still havent got transients right. It worked perfect for a short time after flash and then started going lean at tip in again. This is why I think I need to work on IVT differences like 07GTS talks about. My evap didnt really need adjusting for tip out so I'm leaving that alone for now. He's got a good point about using the EQ error in the scanner, thats what I used to find the lean tip ins as far as MAP goes. Make sure your DFCO and CFCO are disabled.
    Take this advice with a critical eye, I'm still learning.

  7. #7
    Had to work yuck. Could you log IVT and percent off and make changes to table then interpolate? How did you fix rich after flash?

  8. #8
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    I just setup the scanner to log EQ ratio err math , IVT and MAP with the axis labels in the Transients Gas table. I'm trying Percent and Max to start but might need to change to Average.

    Rich after reflash is a pain. That's a bigger topic than I can say here and I don't think you log for it.

    Whatever you do, DONT ZERO THE TABLE!! You will go lean after reflash which is worse.

    You need to add Injector Tip Temp to your PID list and watch that temp. Based out temp will be somewhere in the neighborhood of 118-122*F. After you reflash for any reason, changes or not, it will go way up and affect your Lambda. You will need to adjust this by adding or subtraction the values in the Offset vs. Inj Temp table. ENGINE>FUEL>GENERAL>INJECTOR CONTROL. I added .007813 several times to the upper temp until reflash was stable at .98-1.00 Lambda. I used my WB and just observed the display as the Ins Tip Temp PID came down, then added more or less .007813 as needed, reflashed, repeat......

    Like I said, I'm new too so take my advice at your own risk.

  9. #9
    Advanced Tuner ttz06vette's Avatar
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    I believe higher numbers are richer for impact factor. That?s what worked for me anyway. Thats why the numbers are higher for lower temps. More fuel sticks to the walls during warmup and cooler temps so you need a richer transient. Once hot more fuel atomizes into combustion.

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    I think that is set by the Warm Up tables, but what do I know? When I was tuning this I was at normal operating temps. I figured I would work on warm ups later if I needed to. I don't usually drive my car cold anyways.

  11. #11
    Advanced Tuner ttz06vette's Avatar
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    Quote Originally Posted by marksrig View Post
    I think that is set by the Warm Up tables, but what do I know? When I was tuning this I was at normal operating temps. I figured I would work on warm ups later if I needed to. I don't usually drive my car cold anyways.
    But think about it...the numbers are higher during these temps not the other way.

  12. #12
    Makes sense larger # makes it richer, like I said I had myself pretty confused yesterday. On the warm up I just logged at startup and let it go until operating temps. Then went back and found IVT and percent error and applied that to table all pretty much at 70 kpa then interpolated north and south of that. Did that couple times cold to hot. Worked out good.

  13. #13
    Ok so I just got done with ECT for boundary. 520 all the way across as 70 ECT gave the richest condition. I'm going to rework the injector worksheet.

  14. #14
    will you check out this injector boundary worksheet and let me know what you think?

  15. #15
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    Quote Originally Posted by ttz06vette View Post
    But think about it...the numbers are higher during these temps not the other way.
    So you're right I wasn't even in SD. No wonder things weren't adding up. Thanks

  16. #16
    Bad news it didn't like the 70 ECT. Went lean and couldn't seem to bring it back so I left the boundary and put ECT back to factory 110. IDK got to do what it wants I guess. May try transients tomorrow.

  17. #17
    Advanced Tuner jsllc's Avatar
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    So when engine is cold you have to inject the fuel in earlier. 110 is even too early. Also if you need 17ms to inject fuel then 550 is as far as you want to go.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm

  18. #18
    I did all testing at operating temp 190ish at idle. After making changes I would wait for commanded to reach lambda stop then start recording to get recent afr. Went from 110 90 85 80 70 75 and 60. 70 was richest. But after flash it was lean. And stayed lean. I may have done something wrong. Any advice? I'll try again tomorrow

  19. #19
    Oh the 550 is for the upper rpms yeah, I'm running 52lb injectors. Prob not helping PW. Tried running decaps but didn't have good data and couldn't control them down low. Actually smelled fuel in the oil yikes!

  20. #20
    Advanced Tuner jsllc's Avatar
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    Need your tune to see but best guess you have an injector tip temp issue.
    2012 ZL1 - Maggie Heartbeat, Port & Polish Heads, Custom Cam, Custom rotating assembly, steel sleeved LS9, No NOS and No water meth. 16psi
    810rwhp and 820rwtq 91 Octane 6400 rpm
    948rwhp and 951rwtq 105 Octane 6400 rpm
    999rwhp and 997rwtq on 60% Ethanol 6400 rpm