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Thread: Chrome V2 Tech Manual

  1. #11
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    Fan Control

    The stock fan system is comprised of 2 indepenent fans. The driver side fan is referred too as the a/c fan and the large dual mode fan on the passenger side is the main fan. The Fan Control Temps table controls when the fans turn on and off under various conditions and when the main fan switches to full speed.

    Unfortunately for the performance minded it seems as though Mitsubishi was more interested in reducing fan noise than outright cooling performance. The fans under stock control do not engage full speed until the coolant has already reached 212. The main thing to remember about these settings is to keep a gap of at least 8-10 degrees between the OFF and ON states of each fan or hysteresis may occur and the fans will be constantly turning on and off, reducing the life span of the fans and related components. It would be a good practice to lower each fan setting by an equal amount to maintain the factory gap between ON and OFF states.



    Included in this section is also the Coolant Temp sensor scaling table (again, very large 161 element table) as well as the sensor fault value. If the sensor dies or becomes unplugged, the ECU will use the temperature value in this cell.

    2014 Exomotive Exocet - #101 "shocker yellow" - 1.8L 5-speed 3.9 torsen FMII powered
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  2. #12
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    Limits

    This section contains all the safeties built into the ECU.

    Rev Limit we're all familiar with. The ECU cuts fuel and spark when RPMs > than the value in the table.

    Fuel cut is nothing more than a function which checks airflow (load) and compares it to RPM and if the airflow exceeds the table for 1000ms (or 1 second), it cuts the fuel. It's a great safety feature should your wastegates become disconnected or if you over boost in high gears.

    The double mod was my way around the 1byte limitation. Now the max engine load is 638 LOAD which I don't ever see anyone hitting.

    While tuning, I usually disable fuel cut by setting the timer to something very long (like 5000ms). After everything is setup, I review the peak airflow from the logs and set the table to be about 10-15 load greater and set the timer for 500ms instead of the stock 1000.

    The Speed Limit Function must be enabled in periphery 0 bit 6 in order to function. It's disabled from the factory. When engaged, it only cuts fuel, not spark.


  3. #13
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    Limits

    This section contains all the safeties built into the ECU.

    Rev Limit we're all familiar with. The ECU cuts fuel and spark when RPMs > than the value in the table.

    Fuel cut is nothing more than a function which checks airflow (load) and compares it to RPM and if the airflow exceeds the table for 1000ms (or 1 second), it cuts the fuel. It's a great safety feature should your wastegates become disconnected or if you over boost in high gears.

    The double mod was my way around the 1byte limitation. Now the max engine load is 638 LOAD which I don't ever see anyone hitting.

    While tuning, I usually disable fuel cut by setting the timer to something very long (like 5000ms). After everything is setup, I review the peak airflow from the logs and set the table to be about 10-15 load greater and set the timer for 500ms instead of the stock 1000.

    The Speed Limit Function must be enabled in periphery 0 bit 6 in order to function. It's disabled from the factory. When engaged, it only cuts fuel, not spark.

    Launch Control

    While this feature is nothing like what you find in modern cars with an accelerator pedal assist, it does incorporate a static rev limiter, spark retard and fuel enrichment all which are driven simply off the TPS and the speedometer. No extra inputs are required.

    This function will only work if Enabled in Periphery 1 (Chrome Mods). Quite simply, the ECU will use a lower revlimiter while the speed is less than 6mph and you're holding the throttle greater than 80%. All 3 of these parameters can be edited of course.



    Antilag and AFR enrichment

    While Launch Control is engaged, the ECU will also retard the ignition advance as far back as possible and enrichen the fuel mixture to as heavy of an air fuel ratio as possible to without drowning out the spark plugs and killing the motor. Just a static rev limiter itself isn't able to build as much boost without these two aids.





    NLTS

    Clutch in Rev Limit (also called No Lift to Shift or NLTS) will only work with BOTH bit 2 and bit 4 Enabled in Periphery 1. Clutch in Rev Limit also requires a wire be hooked from one of the two clutch switches to pin 67 of the ECU. Instructions for this will be included later.

    All this function does is change the rev limiter while the clutch is depressed AND when you have the throttle held to the floor. This function cuts fuel and spark thus making the RPMs drop without the need to lift off the throttle during gear changes.

    Depending on which clutch switch you use, you may have to edit the NLTS Clutch Switch Selector value. I recommend people use the Cruise Control Power Kill switch instead of the Starter Switch as the function is enabled as soon as the clutch pedal is pushed down slightly. The cruise switch is also much much easier to get at under the dash.


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    Knock Check Engine Light

    This feature only works with bit 6 enabled in periphery 1. Quite simply, all it will do is illuminate the CEL when knock count exceeds the value in the table. Great safety feature when you're driving and can't take your eyes off the road.

    The default knock sum is 5 but you can edit this value to be anything you'd like.



    Knock

    After a few months of staring at letters and numbers (and a few fights with the girl over obsessing with the computer screen), and thanks to Merlins EVO tuning guide, I think I finally have a good grasp on how the ECU calculates KnockSum and uses the Octane value. There are many similarities between the code logic in our cars and the EVOs, but ours is a bit more primitive.

    We start off with the KnockBase which is the the ground filter for tuning out frequencies. When a signal spike from the knock sensor exceeds this Base filter, it's regarded as knock. This filter level is derived from the knock sensor RAW value (signals from the knock sensor itself) then is passed thru 2 amplifiers which are called the single and triple gain amplifiers. What these amplifiers do is they filter out background noise and amplify low level signals. The ECU has an analog to digital converter (ADC) which takes these signals and multiplies them by something called the Knock Multiplier value with the single/triple gain adders applied.

    This multiplier is used to multiply the difference between the filtered knock and the long term average knock. The result is divided by the long term average knock.

    Knock_Muliplier * (KnockBase - Average_LT_Knock)/Average_LT_Knock

    Basically all this does is it gives the code the ability to learn the engine noises during various RPMs. The 3/S has 2 multipliers. One for low load and one for high load conditions. For some reason, they made both these multiplier values the same in the code... I labeled these as "Knock Sensitivity" in the ECUFlash XML.

    The code uses RPM to switch between the single and triple gain adders. I labeled these as "Background Noise Switch Points" in the XML.

    The KnockBase is updated by taking the old value * 7 then adds the latest knock free noise level and divides all that by 8. So it takes 8 ignition events to fully update the KnockBase.




    *Ignition Retard*

    The ECU has a safety feature coded where it will reduce timing advance when knock is detected. It does this by taking the current timing value and divided it by 90 then subtracts 231 from the result and stores this for later. Knocksum is then added to this value.

    So, here's the formula the ECU uses to reducing ignition timing:

    knocksum*90/256

    In other words, every knock count takes about .32 degrees of timing away from advancement!



    *Fuel Enrichment*

    The ECU also has a safety feature coded where it will enrichen the fuel mixture when a knocksum > 6 is detected. It takes your current AFR value from your fuel table, divides it by 160. There also appears to be a table look up which I *think* is just a maximum enrichment based on coolant temp (all the values are the same and the AFR value translated from hex the values is 8.7). All this means is the farthest the ECU will enrichen your mixture is an AFR of 8.7.

    Let me give an example:

    Lets say in your High Octane fuel table, you have the value of 11.8 in the cell the ECU is currently looking up and you have a knock count of 12.

    (12-6)*160/256 = 3 (rounded down)

    The AFR values in the table comes from this equasion: 14.7*128/x
    So in this case AFR of 11.8 in the table converts to 159.

    Add 4 to that and we have 161.

    Converting 161 back to AFR is 11.6. This this 11.6 is your new AFR number.

    Keep in mind, a knock sum of 12 will bring down the octane number which will interpolate between your High & Low Octane Tables. These 2 functions are completely separate from the Octane function which simply interpolates between the High and Low octane tables.



    *Octane*

    Another area of our code which is a bit primitive to the EVO are the conditions which the ECU uses this value:

    Coolant temp > 178 degF
    Load > 70 (temperature and barometric compensated)
    RPMs must be between 1812rpms and 7500rpms

    Those of you who wish to run a higher redline might want to extend the high value! The max you can set it to is only 7900 though... This is the 1 byte limitation.

    Just like the DSM and EVO, a knock count of < 3 adds to the Octane value and a knock count > 5 takes away from it. Give me some more time to figure out what the hex values mean and I can tell you how quickly and how much it adds or takes away from this value.

  6. #15
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    Turbo

    The biggest problem with every single boost controller ever manufactured is that all the response characteristics of the turbo & engine change so radically with small changes in environmental conditions and/or driving style. It's difficult to get them stable and still responsive under all conditions... Mitsu's answer to this was to have a BCS that functioned off RPM and Engine Load (airflow). The ECU has absolutely no idea (nor does it care) what the pressure is inside the manifold. It targets a desired horse power and adjust the turbos to match.

    The Boost control signal is a constant 16 HZ with varying duty cycle dependent on RPM. Boost solenoid is energized when the ECU pulls the white lead of the solenoid to ground. Logging this Waste Gate Duty Cycle (WGDC) from MUT request 86 shows:

    RPM - WGDC
    2000 - 100% Constantly energized = BCS open
    3000 - 80%
    4000 - 70%
    5000 - 55%
    6000 - 46%
    7000 - 44%



    The higher the duty cycle, the faster it's cycling the solenoid. At 100% WGDC it's bleeding away as much of the air to the wastegates at it physically can. Unfortunately with stock 6psi wastegates, the stock BCS can't bleed away enough air to raise the boost with upgraded turbos. Instead a 3-port solenoid will need to be used. ***More info this setup coming soon in another thread.***

    The highlighted column in yellow is boost, the orange is WGDC. BTW you are seeing that correct. My stock car is boosting almost 14psi stock and it tapers to 7 by the redline. This has been verified on 2 other 99 VR4s and my 98 VR4. The service manual claims 2G cars only boost 10psi stock and as you can clearly see, that's understated! This was on an 85deg day.

    What's interesting is in colder environmental conditions, the car would only boost about 11-12psi. This is because the ECU would lower the airflow from the turbos to achieve it's target airflow. Ever notice that on colder days your car "feels" like it has more power? That's because it does! Colder air is denser therefore you get more power. Since the stock ECU is targeting a specific airflow, it'll lower the boost to compensate for the denser air so horse power is more consistent in all weather conditions.

    Picking apart the code, it starts here with these 2 base tables for WGDC. Turns out, the ECU uses the Octane value to interpolate between the 2 just like the fuel and timing tables. So if knock is detected, the ECU will lower the boost to compensate. These are the high and low octane Base WGDC tables.



    This is just the start. The ECU also has a correction to compensate for Engine Load. Because of this correction, Air Temp, Barometric Pressure and even what gear you're in are compensated!

    There are 4 tables for this and as it turns out, the active exhaust dash switch is the trigger to toggle between these 2 sets of tables.



    What the ECU does is it takes the actual engine load, compares it to the target, then adds/takes away duty cycle to compensate. How much or little to compensate for derives from this table:



    For tuning purposes (or if you'd just like to eliminate this feature entirely) set all the values in this table to 0.

    In Chrome V2, I removed the active exhaust flag and instead programmed a speedometer based flag. You must enable this function in periphery 1 otherwise the ECU will only use set A of the Target Engine Load tables.



    Note: there is also an adder value for target engine load. This is because of a 1 byte limitation in the tables. So your real target engine load is the lookup from the table PLUS this single cell.

    The WGDC correction algorithm operates on timer and I have found the delay time setting that sets interval between WGDC corrections! The stock value is 10. The scaling appears to be 1 unit = 0.08 sec, so 10 units is about 0.8 seconds. This is how often it updates the correction. Since the stock BCS isn't nearly as responsive as some of the aftermarket solenoids out there, there's really no point in changing this.

    There are a few other tables too. One is a correction for TPS, another for coolant temp and the other is a Minimum Load for Boost Control table.



    The TPS table is self-explainitory. It will cycle down the BCS depending on where your foot is on the gas. In otherwords, you must keep your foot to the floor in order for the ECU to use 100% of your maps.

    The Coolant temp table is functions the same way. Until the motor is completely warmed up, it will scale back the airflow.

    The Min Load table is just when the ECU energizes the BCS. I think they put this into the code to prolong the life of the solenoid so it's disabled during low throttle cruise and not constantly clicking when you don't need boost.

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    Boost Gauge

    The stock Boost Gauge signal is PWM based signal sent across a single wire from the ECU. At 100% the gauge points to the top, 0% it's at the bottom. The ECU calculates the Boost Gauge Duty Cycle (BGDC) from a single 2D table in the ECU.



    The axis is just engine load which is calculated from air flow, then compensated for temperature and then is stored in a location in memory. The look up values you see in the table are where the needle physically points on the gauge itself (-8 = bottom, 14 = top). There's really no rhyme or reason to how mitsu setup the gauge. One would think that 100 engine load = 0psi but the engineers probably knew better. After flash tuning a couple cars with the EVOX map sensor, I've been noticing 0psi is actually closer to 75-80 Load which almost matches the table. Who knows...

    In either case, this data is pretty useless. The gauge really just serves as a fuel mileage calculator if anything...

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    Lean Spool

    I like Merlin's description best of what exactly this does.

    Quote Originally Posted by Merlins ECUFlash EVO Tuning Guide
    LEAN SPOOL is a tuning enhancement Mitsubishi employ to reduce the turbo spool time. A gasoline engine will produce hotter exhaust gas and more power at an AFR of 12.5:1 than 10.5:1. It achieves this by running a leaner AFR duing the rapid engine acceleration period than is set-out in the fuel map and in the process produce more torque. All of which results in quicker on-road car.


    You must enable this function in periphery 1 bit 0.

    Lean spool starts at 3000rpms and stops at 6000rpms. These were the default values in memory. It's best to edit these values to match when your turbos first start to spool. The default value in the code is 3000rpms, but on most TD04 turbos, you might want to set this to closer to 2200rpms. I don't see any point in editing the coolant value.

    The Lean Spool Load table is the point above which lean spool will activate. Again, since these values are tuned for the more laggy TD05 turbos, you might want to drop them to something more conservative. My stock 98 sees 1psi at about 75-80 load in 3rd gear WOT.

    The Lean Spool AFR table is how much leaner your AFR will be off the High Octane fuel table. If you want to run .5 AFR leaner, then set the AFR in this table to .5 AFR leaner than the AFR in your fuel table. I wouldn't go past 14.7 in this table unless you enjoy playing with fire.

    The Lean Spool Trailing Time - Rich Side table controls the time of Lean Spool operation through the RPM band. The units you see in the table are how long it will take to return to the normal High Octane fuel map. You'll have to play around with this to see what works best for you. The values populated here are the stock DSM values.

    The Lean Spool Trailing Time - Lean Side table controls the time to go from the High Octane table to the Lean Spool AFR table. Again, these are the stock DSM values.

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    EGR

    Denis has the absolute best write up I've seen about the EGR. Here's a link:

    Far North Racing - Stealth - Programming EGR with the AEM EMS

    Not going to get into too much detail on this as most people just eliminate this system anyway.

    Note: if you feel the need to disable the code (thus disable the pin) use the switch in this section, not in periphery 0.



    The solenoid that operates the EGR is a duty cycle based setup just like the boost controller. Likewise it has a coolant temp interpolation.

    The last table is just an EGR offset to verify the valve is still functioning. If you decide to keep the EGR and run the EVOX map sensor, this table must be updated with the EVOX values:

    750 84
    1000 84
    1250 73
    1500 65
    1750 60
    2000 55
    2500 48
    3000 43
    3500 23

    This thread is now outdated but I'm linking it for the discussion on the EVO sensor. You do not need to perform any of the other ROM changes noted.

    http://www.3sgto.org/f104/disassembl...nsor-8260.html

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    Purge

    Again, another system that most people eliminate. Unfortunately the purge system on the 98/99 flash ECU is NOT compatible with the 91-95 gen cars. The 96/97 guys are fine and don't need to change anything.

    The reason is the OBD2 purge solenoid is a duty cycle operation like the BCS and EGR solenoids. The OBD1 cars have an on/off type solenoid. If you just plugged in your flash ECU and didn't disable this solenoid, you'll notice a rather obnoxious clicking sound at idle. This is because the ECU is triggering it on/off like the OBD2 solenoid.

    You have 2 options for a fix:

    *Since the stock BCS is fairly useless, swap that solenoid in place of the purge and it will function just like on a 98/99 car.

    *Use one of the Chrome Custom Pin Outputs. ***details in a later post***

    If you eliminate this system you must switch bits 15, 14 and 13 off in periphery 2 to avoid a CEL.

  11. #20
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    Active Exhaust

    So it turns out, not only is this still coded in the 99 ROM, the hardware is also still installed on a Flash ECU board!

    In a stock ROM the Active Exhaust (AE) ONLY effects ECU controlled boost and nothing more. I've basically re-writen this entire area of the code to simplify it's function.



    The ecu registers the active exhaust in "sport mode" when pin 75 of the flashable ECU sees ground. This is switched to ground by the AE dash switch in the 91-94 cars. While this switch is missing from the 95+ cars, Adam and I have verified the dash harness is still in place on all VR4s. Installation is quite literally plug and play! ***install write up coming soon***

    Pin 7 on the flash ECU is the output for the Active Exhaust controller. (also ties to ground) If you'd like to keep this function in your 91-94 car, make sure your ECU adapter harness has these pins populated. This is a new function for Chrome V2 so chances are, if you've purchased an adapter harness, it's still blank.

    If you don't have a dash switch, but still want to use the AE function for your own exhaust cut out, I programmed a by-pass into the code so the system will still function without one.

    The system will only function with bit 13 enabled in periphery 1 and when BOTH TPS and RPM conditions are met. If you don't disable the dash switch function in the code, the dash switch must be set to sport mode.

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