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Thread: Injectors, Regulators, and MPTune.

  1. #1
    Garrett booster
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    Injectors, Regulators, and MPTune.

    Hey everybody. I’m running a Smec 2.5 turbo with T2 turbo, intercooler, and boostbutton stage 2 cal. I picked up 65pph injectors for a reasonable price (less than +40s actually). Ever since I installed those injectors, the Spirit bogs off the line a bit and has trouble starting during a cold morning. At wide open throttle, everything stays comfy between 12-13 air/fuel.

    Right now I have the fuel pressure set to 28psi. Is that a reasonable setting, or should I set higher or lower?

    I appreciate any thoughts :-)

  2. #2
    Hybrid booster
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    Re: Injectors, Regulators, and MPTune.

    Did you check your wideband to see if it's running rich low?

  3. #3
    Garrett booster
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    Re: Injectors, Regulators, and MPTune.

    Ya everything seems good on the air/fuel gauge. I guess I’m a little worried about the spray pattern with a large injector and low fuel pressure.

  4. #4
    Garrett booster Turbo Mopar Contributor
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    Re: Injectors, Regulators, and MPTune.

    I don't consider myself any kind of expert, but I'll take a stab at helping. (Assuming that you are already in a position to tune your own cal).

    First general advice is reel it back. Get things ironed out on your minimum boost and go up from there. Most advice I've seen would suggest that 12-13 AFR is lean. I'm trying to shoot for 11.5AFR @WOT myself.

    Do you have a link to the injectors you bought? Their 65lb/hr rating is likely at 43.5psi where the MP +40s were supposed to be 52lb/hr@55psi. Some have found their +40s flowing more than that. If your new injectors are in fact rated at 43.5 you can use an online calculator to figure out what they flow at 55psi. In MPTune you can create that as an injector size, use that to scale your cal and bump your fuel pressure to 55psi (static) and see how the car runs.

    Did they come with any "latency"/"dead time" data? These are likely different than the stock values in the cal. If they came with the data or if you can locate it, you can use those values to edit the cal's FuelBatteryOffset table. This could have been a factor for your rich idle.

    Have you read through the old BoostButton wiki? Info on creating a base cal https://pcm.neons.org/doku.php?id=base_cal_setup
    Last edited by Dan H; 10-08-2020 at 01:11 PM.

  5. #5
    Garrett booster
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    Re: Injectors, Regulators, and MPTune.

    Quote Originally Posted by Dan H View Post
    I don't consider myself any kind of expert, but I'll take a stab at helping. (Assuming that you are already in a position to tune your own cal).

    First general advice is reel it back. Get things ironed out on your minimum boost and go up from there. Most advice I've seen would suggest that 12-13 AFR is lean. I'm trying to shoot for 11.5AFR @WOT myself.

    Do you have a link to the injectors you bought? Their 65lb/hr rating is likely at 43.5psi where the MP +40s were supposed to be 52lb/hr@55psi. Some have found their +40s flowing more than that. If your new injectors are in fact rated at 43.5 you can use an online calculator to figure out what they flow at 55psi. In MPTune you can create that as an injector size, use that to scale your cal and bump your fuel pressure to 55psi (static) and see how the car runs.

    Did they come with any "latency"/"dead time" data? These are likely different than the stock values in the cal. If they came with the data or if you can locate it, you can use those values to edit the cal's FuelBatteryOffset table. This could have been a factor for your rich idle.

    Have you read through the old BoostButton wiki? Info on creating a base cal https://pcm.neons.org/doku.php?id=base_cal_setup
    Hey Dan,
    Yes I've read through the BB wiki and enjoyed it very much! There are a few things that are going over my head tho. BUT, I am learning :-)

    Here is the link to the injectors: https://www.fwdperformance.com/Store...ProductID=1403

    The only reason I started at 28psi is because Donovan's site it describes how to run big injectors with a regulator by dialing back the fuel pressure. But is that just the old school way of doing it? I'll reflash my chip to run on 55PSI and see what happens.

  6. #6
    Garrett booster Turbo Mopar Contributor
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    Re: Injectors, Regulators, and MPTune.

    Quote Originally Posted by Fenderbass View Post

    The only reason I started at 28psi is because Donovan's site it describes how to run big injectors with a regulator by dialing back the fuel pressure. But is that just the old school way of doing it? I'll reflash my chip to run on 55PSI and see what happens.
    Yeah, generally that would be the old way before we had such easy access to modifying the cal.

    You should be able to set your base pressure at 43.5psi static, create the injector size of 65pph in MPTune, then scale the cal.

    If you have (or can find) the latency values for those injectors edit the FuelBatteryOffset table with them. If not, I would try copying that table from the S60 cal.

    If you have already scaled your current cal multiple times, you're probably better off starting fresh.

  7. #7
    Garrett booster Turbo Mopar Contributor
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    Re: Injectors, Regulators, and MPTune.

    What size injector was your current Cal set up for?

  8. #8
    Garrett booster
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    Re: Injectors, Regulators, and MPTune.

    Cal is setup for 65pph and I just upped the fuel pressure from 28psi to roughly 43.5psi on the regulator (and updated the AFR on MPTune). HUGE difference on drivability!!! No bogging!!! I haven’t done a complete cold start yet, but I’m sure this recent burn will make a big difference.

    Thank you, dan.

    I didn’t change anything under the Injector (Bar option). Should I adjust that too?

  9. #9
    Garrett booster Turbo Mopar Contributor
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    Re: Injectors, Regulators, and MPTune.

    Glad it's going in the right direction.

    I'm not sure exactly which spot you mean the bar option? Under scaling or in the AFR setting chart?

  10. #10
    Boost, it's what's for dinner... Turbo Mopar Staff Aries_Turbo's Avatar
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    Re: Injectors, Regulators, and MPTune.

    want me to do a base cal for your setup?

    let me know exactly what you have and i can make something that is close.

    you will have to tune in pumping efficiency and advancefrommapwarmpart and advancefrommapwarmfull.

    most everything else will fall in line.

    Brian

    - - - Updated - - -

    also, i will teach you what i know......

    Quote Originally Posted by turbovanman
    This one is easy, I have myself to blame, I rush things, don't pay attention to gauges when I should, change to much stuff at once then expect miracles, the list is endless.

  11. #11
    Supporting Member Turbo Mopar Contributor
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    Re: Injectors, Regulators, and MPTune.

    Quote Originally Posted by Aries_Turbo View Post
    want me to do a base cal for your setup?

    let me know exactly what you have and i can make something that is close.

    you will have to tune in pumping efficiency and advancefrommapwarmpart and advancefrommapwarmfull.

    most everything else will fall in line.

    Brian

    - - - Updated - - -

    also, i will teach you what i know......
    Awesome... please include me in the conversation. The tune Brian created for me is 95+% what I needed. A/F are near perfect. Currently only running to 12psi as the car only been on the road for 2 months.
    Brian, the only serious issue I have is wheel spin at WOT from 2nd to 3rd. I was thinking I need to replace the Stage 5 4 puck clutch back to stock to eliminate the wheel spin.
    Regards,
    Miles

    DD '87 Sundance T1, SLH with rear disks
    '87 CSX #432 2.5 CB TII, SLH

  12. #12
    Garrett booster
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    Re: Injectors, Regulators, and MPTune.

    Quote Originally Posted by Aries_Turbo View Post
    want me to do a base cal for your setup?

    let me know exactly what you have and i can make something that is close.

    you will have to tune in pumping efficiency and advancefrommapwarmpart and advancefrommapwarmfull.

    most everything else will fall in line.

    Brian

    - - - Updated - - -

    also, i will teach you what i know......
    pm sent!

  13. #13
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: Injectors, Regulators, and MPTune.

    Quote Originally Posted by chromguy View Post
    Awesome... please include me in the conversation. The tune Brian created for me is 95+% what I needed. A/F are near perfect. Currently only running to 12psi as the car only been on the road for 2 months.
    Brian, the only serious issue I have is wheel spin at WOT from 2nd to 3rd. I was thinking I need to replace the Stage 5 4 puck clutch back to stock to eliminate the wheel spin.
    How are the struts? My old shadow would spin the tires into 3rd every time until I put some decent struts in it.

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