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Thread: P59 2bar OS question

  1. #1
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    P59 2bar OS question

    For those that may have tried it or have experience, will the map still compensate for boost if the maf is maxed out? I know for a fact that the maf sensor still works with the 2 bar os because that's the way it's running in my truck right now. It's not maxed but I'm building an lq4 to replace the current boosted 5.3. I had to turn the maf back on because in speed density there's no way around lean hot restarts and it kept carrying lean values into power enrichment.

  2. #2
    Advanced Tuner kingtal0n's Avatar
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    I use a 411 ECU 2-bar OS 5.3L Turbo app

    I do not recommend using the MAF in a forced induction application when MAP is available.

    In my ECU there is a map which configures IAT fuel compensation for power enrichment which prevents high IAT From leaning out PE.
    There is also a map which configures A/F ratio enrichment for restarting the engine "heat soak" enrichments.
    If the IAT Is wrongly raising, I recommend relocating it. Before the engine or closer to the intercooler outlet is ideal.
    You can additionally wire a 500Ohm or 1000Ohm variable resistor between IAT and ECU for real-time control of IAT based timing and fuel functions.

    These together should prevent any concern regarding hot refire if you have these options in your tune file available.


    Next, for 2-bar applications in general (I tuned Haltech, AEM, megasquirt, power FC this way in the past) when using around 18 or 20psi of boost max, I prefer to use 2-bar map sensor. The 2-bar will max out at 15~psi of course, but you simply tune the last row for the max boost a/f ratio. Boost will shoot quickly through 15 16 17 18 19psi, the a/f curve will dip briefly but rapidly correct as target boost is obtained.

    This allows the advantage of high resolution fuel map which the 2-bar provides. 3-bar sensors should be used for say 21+ Psi of boost, but their decreased resolution is a trade off.

  3. #3
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    The maf sensor has been working well in my application for over 50000 miles so I'm good with using it. I have a tvs1900 so my iat is in the intake can't relocate it. My sd problem is on a hot restart the iat is obviously heat soaked so the trims pull fuel until the iat is normal again. There is no way around it it's a pitfall of sd. This is a daily driver so there are times when I can't baby it around for 10 minutes until the iat comes back down. I have a 2 bar map in it and it was tuned in sd but the maf had to be enabled to fix the heat soak problem. None of the other tables do a thing I've tried them. Was just curious if someone had maxed a maf while in mixed mode and had the ve table still work in boost. Guess I'll have to be my own guinea pig n hope it doesn't pop the motor

  4. #4
    Advanced Tuner kingtal0n's Avatar
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    Quote Originally Posted by 92rsz View Post
    The maf sensor has been working well in my application for over 50000 miles so I'm good with using it. I have a tvs1900 so my iat is in the intake can't relocate it. My sd problem is on a hot restart the iat is obviously heat soaked so the trims pull fuel until the iat is normal again. There is no way around it it's a pitfall of sd. This is a daily driver so there are times when I can't baby it around for 10 minutes until the iat comes back down. I have a 2 bar map in it and it was tuned in sd but the maf had to be enabled to fix the heat soak problem. None of the other tables do a thing I've tried them. Was just curious if someone had maxed a maf while in mixed mode and had the ve table still work in boost. Guess I'll have to be my own guinea pig n hope it doesn't pop the motor

    I feel like a simple 1000ohm resistor on a switch through the iat would allow you to ditch the maf and avoid heat soaking. It is the simplest solution if your ECU lacks the heat soak table and also doesn't have the IAT adder for power enrichment. I think its very weird that you are missing those tables, seems integral to the 2-bar OS. Can you take a screen shot of your PE window in the software? It should have a IAT vs PE button or something like that.

  5. #5
    Advanced Tuner Atomic's Avatar
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    I think he means the tables are there but he just hasnt had any success getting them to make any difference for hot restarts.

  6. #6
    Advanced Tuner kingtal0n's Avatar
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    Quote Originally Posted by Atomic View Post
    I think he means the tables are there but he just hasnt had any success getting them to make any difference for hot restarts.

    One time, somehow, I accidentally put a 1 into the heat-soak timer enrichment table for "number of seconds since engine restart" and I Didn't notice.
    The number should have been like .016 or something like that, and instead there was a solid 1 in some cells, for between like 240seconds and 550seconds since engine off.

    I would shut the car off, and it would restart perfect until I hit that 240seconds range like when I ran into a wawa for a drink or whatever. I would come back to the car turn the key, the engine would fire up and then it would run so rough and so rich that I would have to rev it and basically hold the throttle nearly wide open just to keep it running. It ran so rich the wideband wouldn't even give me a number. It was so rough I thought the fuel pump was going bad.

    Took me a few days to figure that one out. There are alot of maps in the ECU and some of them can really mess you up if you put a wrong number and don't realize.

    But anyways. What Im saying is- right map, right number, right enrichment. The tools are there. It can run rich enough, I've seen it happen.

    I would open my map but my tuning laptop is still at school because im using it to program microcontrollers in my lab these last couple of months.
    Teaching freshman engineering courses, they are building arduino-controlled cars this semester, ultrasonic sensor for obstacle avoidance and line tracking code. Pics or it didn't happen!

    Some are still in high school.
    Last edited by kingtal0n; 12-10-2021 at 02:56 AM.

  7. #7
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    For whatever reason the p59 has some quirks to it that make it act differently than the p01. I have the hot soak tables mentioned. I never could get them to change the fueling. No matter what I did the trims would always trend lean on a hot restart. If I touched pe it would take those values and pe would then be pig rich. The vehicle is a heavy truck so I can get into pe very easily (20% throttle will do it) with this blower. I'll revisit those tables with bigger numbers to see if they do anything. I appreciate the input.