Part throttle boost (closed loop) tuning for FI

Discussion in 'Engine & Performance Modifications' started by Mr MoPar, Jun 7, 2009.

  1. TALON

    TALON SRTV8

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    I took my car out for some testing this morning, and now I'm quite alarmed.

    Outside temp - 64 degrees
    Engine temp - 181 degrees

    Cruise temps - 1320 degrees

    Full boost - 1392 degrees with a AFR of 10.7 & water/meth spray

    WOT - 1448 degrees with a AFR of 10.9 @ 7 lbs of boost & water/meth spray

    On different runs the AFR ran between 10.7 - 11.2

    I wonder if these higher temps could come from being so close to the cat?

    Ken
     
    Last edited: Jun 16, 2009
  2. Mr MoPar

    Mr MoPar New Member

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    Check and see what your Intake Air Temps are (IAT). Also, is your IAT sensor downstream or upstream of the water/meth injection point?

    What sparkplugs are you running?

    Is your water/meth using a progressive controller or do you have to adjust it at the pump?

    Temps are a little higher than I have seen, but they may be less on a 5.7 like I run. But then again, it could simply be differences in the actual gauge calibration. Your actuall rise is not that much, between 72 and 128 degrees. I am confused between the full boost temps, and WOT. Was the full boost temps in closed loop part throttle?

    The probe location is fine, cat is not going to have an affect.
     
  3. Quick

    Quick Mgmt. - I can't help you

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    We have this really radical concept here where we allow free speach and try to keep the technical discussions based on facts and science :D
     
  4. TALON

    TALON SRTV8

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    Thanks Ken
     
  5. Hemissary

    Hemissary Cogito Ergo Zooom

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    I have not had time to read the entire thread so please forgive me if this has been pointed out;

    Where the EGT probe is placed, the type, and the means by which one reads it can/will result in SIGNIFICANT variations when attempting to compare values from one vehicle to the next.
     
  6. BlownHemi

    BlownHemi It feels good to be blown

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    My aeroforce gauge (reads the ECM calculation not an actual probe) says my cat temp is about 1550 at 75-80 mph cruise speed. IAT sensor is in the intake and runs 190. I have EGT bungs in all cylinders about an 1" or so from the exhaust port courtesy of Kooks but haven't put probes in yet. Thanks George! The cat temp calculation is hardly ever below 1250-1300. I have an offroad setup with no cats. No methanol yet, no intercooler, 6-71 blower, 426. What do you guys think? Is the "calculated" temp off due to other parameters that the ECM doesn't account for?

    Also whats the difference in reading at the port versus down at the collector? I thought reading at the port was more accurate and the proper way. Not saying anyones doing it wrong just asking
     
    Last edited: Jun 16, 2009
  7. Quick

    Quick Mgmt. - I can't help you

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    I think so. The PCM is modeling the cat temps. It's more than likely making a whole bunch of assumptions that everything is stock physically. ..and then it's a model and probably averaged/smoothed whatever. Kind of like commanded afr can be different than actual afr
     
  8. Mr MoPar

    Mr MoPar New Member

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    Okay, your water/meth looks fine from what you describe. The one thing that does look abnormal to me are your spark plugs.

    The number you quoted appears to be the stock plug number. What you should be running, is the NGK LTR61X-11 which is two steps colder than stock. I would strongly suggest changing the plugs.

    Were the plugs you have supplied with the SC or are they the actual stock plugs?

    You can check your IAT temp with either the Diablo Predator dataloging or a Dashhawk or similar (scan gauge) if you have one of those.
     
  9. Quick

    Quick Mgmt. - I can't help you

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    Is what this guy says correct?

    http://www.stevetek.com/R-EGTprobeLocation.html

    He is checking it. But you asked if his IAT sensor is upstream or downstream of the meth. It's upstream (before) the water/meth.
     
  10. Mr MoPar

    Mr MoPar New Member

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    Mike (Lafrad) had commented that the temps he was seeing on the calculated cat temp was close to what he saw on the actual EGT gauge. Hard to say if what you are seeing is correct or not, you are heavily modified.

    As far as probe location, obviously located right at the port is more accurate, on a stock manifold vehicle, most locate it just below the exhaust manifold flange above the cat due to ease of installation.

    Is your IAT temp (190) at cruise or under full boost?

    Are you seeing any knock retard under boost?

    If you are the person I spoke to on the phone, disregard this question, but if not, are you doing anything to cool the rotors on the blower? If I did talk to you, give me a call sometime and update me on your project

    I would agree with the link you posted, actual engine testing is done at the port on each cylinder with an EGT and an AFR probe.

    Yes, his meth spray location is fine. I always prefer to spray downstream of the IAT, this is in line with the manufacturer I use recommendations as well.

    The reason is that when spray comes on, your IAT (if downstream) would see a sudden drop in temp. The ECU will respond with some additional fuel, but it will also add more timing which you do not want under boost.
     
  11. Quick

    Quick Mgmt. - I can't help you

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    So Ken, I think the answer is: that is the IAT reading that you want to check. It's after the aftercooler and before the meth. That's the temperature you want to keep under control. If you are taking your IAT after the meth then you are "tuning for the meth" which everybody seems to advise against. 1) it's not easy and mostly 2) if you run out of meth or it malfunctions you could be toast. Better to use the meth to provide an extra margin of safety/cooling rather than use the meth to squeeze some more power out of it by tuning for it.
     
  12. Mr MoPar

    Mr MoPar New Member

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    The IAT temp will give me an indication of how well his intercooler is functioning, if he is HOT after the intercooler, he may want to upgrade his spray nozzle size and run additional spray. If he can go to 100% spray at 5 psi without blowing out the spark now, then he has room to increase the amount of spray which will provide additional cooling.

    But first he needs to change out those stock plugs.
     
  13. TALON

    TALON SRTV8

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    The NGK spark plugs that I'm running are NOT the OEM plugs. I was told they are 1 heat range colder. The OEM plug is a, NGK PLZTR5A-13

    Ken
     
    Last edited: Jun 16, 2009
  14. Mr MoPar

    Mr MoPar New Member

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    I did not have the stock number with me, that is why I was asking, but I would still change to the two step colder plug, it will help lower temps a little, just a suggestion.
     
  15. TALON

    TALON SRTV8

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    Thanks Tim for the suggestion. New plugs are on there way, every little bit helps.

    Do you suggest keeping the spark plug gap at 35 with the new colder plugs?

    Ken
     
  16. Mr MoPar

    Mr MoPar New Member

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    At lower levels of boost, I have always gapped at .040, and .035 at higher levels of boost. High levels of boost tend to blow out the flame on a larger gap. If you are doing okay at .035, I would leave it there, may also allow you to run more spray.

    Like I mentioned, if you can tolerate 100% spray at 5 psi, then you should be able to move up to the next larger spray nozzle and run a bit more spray which will help cool things down.
     
  17. TALON

    TALON SRTV8

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    I have another larger spray nozzle, I think I'll give it a try.

    Ken
     
  18. Mr MoPar

    Mr MoPar New Member

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    They generally have a pretty big jump in size, divide the old by the new ML rating and go by the percentage, should help in setting it. For example, if has a 50% larger capacity, then 50% pump out put at 5psi should be close to the smaller nozzle set at 100% pump output at 5 psi. But keep in mind, that the flow rate is not going to be exactly linear, as pressure increases flow volume will increase in a non linear curve up to the point where you hit the limit of the orifice size, then as pressure increases, the flow rate increase will not rise as much.

    So what ever the percentage is, start at about 10% more and work your way up from there.
     
  19. TALON

    TALON SRTV8

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    Two step colder plugs aren't available for the 6.1L, that I could find. I tried NGK, Bosch, Champion, and Autolite.

    Ken
     
  20. SRT8U

    SRT8U Supporting Vendor

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    What plugs are you running now Ken?