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Thread: High Idle RPM

  1. #1
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    High Idle RPM

    I got an Ostrich 2 last week, and have been reading the forums like crazy. I have been able to successfully use the new MPTune and have the car running via the Ostrich. I am using the T_LM_22_MTX_S-III calibration. I scaled the injectors for 42# and the Map sensor to a 3-bar. My car has an extensively ported 4323287 head with 1mm oversized valves, a 2-piece manifold, +40 injectors (running 40PSI at idle, 50PSI with 11 PSI of boost). I fixed my spark blowout problem by installing a set of Champion RN9YC gapped to .025"

    The car starts fine, and idles at around 1000 RPM when cold, with a nice 14.5 AFR. Once the car warms up though, it idles at 1300. When decelerating the AFR hangs around 10.2 and 2000 RPM until I hit a dead stop. The car is also hard to start from a dead stop. The AFR drops to 16.5 until it gets rolling - after it's moving, everything is fine. AFR at WOT is 10.3 (I scaled the cal to use #52 injectors and the WOT AFR dropped to 13, everything else stayed the same).

    Also, the car pulls steady to 6000RPM but it lacks power between shifts. On a different cal I was able to chirp the tires hitting 3rd at 5200RPM, but with this I can barely get a chirp shifting into 2nd.

    Any ideas what I need to change to bring my idle speed down? I have ordered an FTDI cable which will hopefully be here this Wednesday. Until it arrives, the only thing I can monitor is my wideband.

    Thanks for any help - coming from the world of mechanical distributors and 4-bbl carbs, this computer controlled turbo stuff is quite foreign to me.

  2. #2
    Supporting Member II Turbo Mopar Contributor tryingbe's Avatar
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    Re: High Idle RPM


  3. #3
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    Re: High Idle RPM

    Thanks for the tip - I'll document my tuning here in case anyone else needs it (but mainly so I have a reference point).

    I started with the T_LM_22_MTX_A171_Stock cal, then :
    • I scaled it for 42# injectors and a 3-bar MAP.
    • I set the AFR tables as follows:
      • No throttle I interpolated from 18@0PSI to 14.7@60PSI
      • Part throttle 14.7 from 0 to 3, 13.5 from 4 to 13, and 13 from 14PSI to 60PSI
      • Full throttle varies from 14.7 to 13 from 0 to 13PSI and 11.5 from 14PSI to 60PSI
      • Intake air @60C, max RPM 6000, 55PSI for both settings, and .740_Regular fuel (I run Sunoco 93)

    • MAPTBL (FuelPartThrottle) I set to match the overlay
    • WOTTBL (FuelFullThrottle) I set to match the overlay
    • PEFTBL (PumpingEfficiency FromRpm):
      • 2409 RPM, 89.804%
      • 3309 RPM, 88.235%
      • 4015 RPM, 93.333%
      • 4658 RPM, 92.941%
      • 5911 RPM, 81.176%

    • POSSLP (PumpShotCalculation, TPS, Enrichment FromTemp) I scaled the table in the Y-axis by 125%, left the X-asix alone


    The car starts great, cold idle AFR was 12, as soon as it warmed up it idled at 14.5 AFR, 850 RPM. When coasting in neutral, idle was only 1200 RPM. The car pulls hard, chirps into 2nd when shifting over 3000 RPM. It also does not lean out (or bog) when taking off from a stand-still. This is the best it has ran since I got the new motor going. Thanks for everyone's help so far.

    The only issue I had was a bad stumble (felt like I hit the rev-limiter) at 4500 WOT in 1st. I'll not do any more hard driving until I get my logging setup. But I think I am at a very good starting point.

  4. #4
    Buy my stuff!!!!!!!!!!! :O) Turbo Mopar Vendor turbovanman²'s Avatar
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    Re: High Idle RPM

    Quote Originally Posted by MoparStephen View Post

    The only issue I had was a bad stumble (felt like I hit the rev-limiter) at 4500 WOT in 1st. I'll not do any more hard driving until I get my logging setup. But I think I am at a very good starting point.
    Your going to need to adjust your PE table as the stock PE table at that rpm drops down big time as the stock head can't flow, you'll need to flatten it out and/or could be your boost cutout is set too low, we just disable it and max out all the limiters.
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    Re: High Idle RPM

    Quote Originally Posted by turbovanman² View Post
    Your going to need to adjust your PE table as the stock PE table at that rpm drops down big time as the stock head can't flow, you'll need to flatten it out and/or could be your boost cutout is set too low, we just disable it and max out all the limiters.
    I'll mess with the PE table as soon as I get my FTDI cable in. I did bump it up, but I pretty much kept the same curve. With the port work, large cam, and 3" exhaust, I am certainly flowing well above a stock setup.

    I did not mess with the boost cutout. The car did not cut out in 2nd or 3rd, it only did this in 1st. It felt like my prior spark blowout issue, but I seriously doubt that is the case now. I have a brand new coil, slightly larger than stock, all new plug wires, new cap, rotor, etc. I am currently running a manual boost valve set to 11PSI. After I get the motor properly broken in, I plan on running 14.5. I plan on switching over to computer controlled boost as the manual boost comes on too hard - once it snaps past 7PSI, I get no traction in 1st or 2nd gear. It's fun, but not good for controlling the car or making good times.

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    Re: High Idle RPM

    Quote Originally Posted by MoparStephen View Post
    I'll mess with the PE table as soon as I get my FTDI cable in. I did bump it up, but I pretty much kept the same curve. With the port work, large cam, and 3" exhaust, I am certainly flowing well above a stock setup.

    I did not mess with the boost cutout. The car did not cut out in 2nd or 3rd, it only did this in 1st. It felt like my prior spark blowout issue, but I seriously doubt that is the case now. I have a brand new coil, slightly larger than stock, all new plug wires, new cap, rotor, etc. I am currently running a manual boost valve set to 11PSI. After I get the motor properly broken in, I plan on running 14.5. I plan on switching over to computer controlled boost as the manual boost comes on too hard - once it snaps past 7PSI, I get no traction in 1st or 2nd gear. It's fun, but not good for controlling the car or making good times.
    Yeah, the stock PE curve pretty well falls off flat, so generally for a setup like yours, lift it up and then flat line it around 55-7000 then drop it down again.

    I think in the template the boost cutout is 14.7, its not adjusted until you do it, so you could be hitting that in first.
    1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
    1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
    2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
    2004 GSW TDI, 5 speed, fully loaded, modified.

    Aurora ignition wires for sale. Link to info

    Super60 roller cams or custom/billet cams. Link to info

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    Re: High Idle RPM

    Quote Originally Posted by turbovanman² View Post
    Yeah, the stock PE curve pretty well falls off flat, so generally for a setup like yours, lift it up and then flat line it around 55-7000 then drop it down again.

    I think in the template the boost cutout is 14.7, its not adjusted until you do it, so you could be hitting that in first.
    Sorry for all the questions - I am having trouble finding where the boost cutout is in this cal - I went through all the tables in both Boost - Target Lookup and Boost - WG Control. The only thing I found was in the OB, Speed, Rev Limiter - OverboostFuelShutoffEnablePointFromMap, which is set to 13.662 PSI. I really don't think I ever hit above 11PSI with my manual valve, but I would like to set this cal to allow for boost of around 18PSI.
    Last edited by MoparStephen; 07-08-2013 at 10:27 PM. Reason: Added more text

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    Re: High Idle RPM

    yep your in the right table..you will see on the left in the categories the on that say OB, Rev limit etc... its in there, i had the same issue, i figured when rescaled for 3 bar it would raise the overboost, nope... chaced that down for a week before i realized the overboost was still set at like 13 psi... DOH... raised it to 29.4 and walla!! my boost gauge was saying 14-15 psi but i was hitting the overboost, just goes to show how accurate the gauges reall are... bump your OB up and raise up the PE too, those number for your air fuel ratio are way to high... 11.5-12.0 would be a great point to shoot for, provided your not getting any knock..

    go into all the tables in the OB section and bring them up to the 29.4 (3bar) and you will never have to wrry about it again... provided you keep to that 18 psi... but you know how it is, we get curious and want to turn the boost up... i told my self in my daytona that yeah 20 psi will be it... psssh yeah right... 26 psi later!! lol

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    Re: High Idle RPM

    Awesome - thanks for the info. I must keep the boost at 14 It's taken me 6 years to get the car to this point, I am too scared to kill this motor before I get a few thousand miles on it.

  10. #10
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    Re: High Idle RPM

    as long as you have the fuel and the right timeing, turn it up!!! have fun with her!!

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    Re: High Idle RPM

    I should be good on fuel - I have a Wahlbro 255 pump, all new steel lines, and 4 +40s running at 50-55PSI under boost.

    Any idea what the bottom ends on these are good for? I am running an 8-bolt cast crank which has been internally balanced, ARP main studs, T2 forged rods which have been bushed and balanced, ARP rod bolts, and forged Wiseco pistons +.020". Just a few weeks ago I watched a neighbor of mine try to run 30PSI of boost in a Honda Del-Sol, it lasted for 20 seconds then blew 4 holes in the block. It wasn't even his car! He still doesn't have it rebuilt for the guy. This is why I work on my own stuff.

  12. #12
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    Re: High Idle RPM

    I have heard/read that the combo you have should be good for 375hp based on the crank. I would love to hear a more educated number though as that is the exact combo I am going for.

  13. #13
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    Re: High Idle RPM

    Good to know, as 300 was my goal. I want something that will last for 100,000 miles, not just go fast for two or three races.

  14. #14
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    Re: High Idle RPM

    300-350 hp shouldnt be an issue, i ran 26 psi on a stock 2.5L and she was pretty happy... on your build you rods are the weak point now, but shouldnt be a problem at the boost levels you will see, just keep that tune happy and all should be fine..

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    Re: High Idle RPM

    With that bottom end, it will last an easy 500 whp as long as you don't detonate or lean out.

    You see 11 psi but sometimes it can creep so fast that the computer reacts faster than you hence why sometimes you'll hit cutout. I would raise it to 18 psi, gives you room to run 11+ psi without danger of hitting it.
    1989 FWD Turbo Caravan-2.5 TIII, GT35R, auto, a/c, cruise, pwr windows/locks, fully loaded with interior and ran with full exhaust. RETIRED FOR A FEW YEARS! 12.57@104 :O)
    1984 Chev Getaway van, 6.2 Diesel with a remote mounted turbo setup burning WMO-For sale.
    2003 GSW 2.0L TDI, auto, fully loaded, modified, 360K-wife's.
    2004 GSW TDI, 5 speed, fully loaded, modified.

    Aurora ignition wires for sale. Link to info

    Super60 roller cams or custom/billet cams. Link to info

  16. #16
    Supporting Member II Turbo Mopar Contributor tryingbe's Avatar
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    Re: High Idle RPM

    Set the PSI to 7psi, WOT at 2nd or 3rd gear and make sure the A/F is 11.5 throughout the RPM range, if not, adjust the pump efficient table to make it to.

    That's how you tune for the PE table.

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