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Thread: Nothing makes sense. No consistency in the tune $8D mask

  1. #1
    Fuel Injected!
    Join Date
    Nov 2016
    Posts
    38

    Nothing makes sense. No consistency in the tune $8D mask

    My tune is consistently inconsistent. It does whatever it wants to do. I tested it. I set my 1600-5600rpm VE map all cells to 96 and sent it to the ECU then drove it. it made absolutely no difference in the drivability and AFR's did their usual thing, no change. I even tried changing injector size. My idle with 32lb injectors was 17-18 AFR so input in fuel injector flow 22lb/hr aka stock for L98 engine. it instantly put my AFR's in 11's, then I drove it made no difference driving. Then I set injector flow to 27lb my idle AFR was perfect at 14.7, drove it and made no difference driving AFR's were still rich and lean in all the places I'm trying to fix. So WTF is going on here seriously! Another issue is the Open Loop when cold. I need to find a way to tune it, turn it off sooner at lower coolant temps or eliminate it all together. my car runs in the 10's AFR in open loop. It's about 50-60*F in Pheonix AZ right now and as soon as the car gets going the coolant temps go down a bit and it seems to be enough to put it back into open loop and starts running way too rich. Unless someone has a suggestion on how to keep the engine temps consistent and warm. I'm already using a 195*F thermostat. Last thing, Cell trace. It works when it feels like it. Today it worked and then I stopped at the gas station to get fuel and turned the car off left the computer on tunerpro running, restarted the car and cell trace wouldn't work anymore.

  2. #2
    Administrator
    Join Date
    May 2011
    Location
    Lakes Region, NH
    Age
    47
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    2,763
    If you decide the ecm is in charge you have no hope of getting this to work. You are in charge, the ecm is doing exactly what you've told it to do, even if don't know exactly what you're saying yet.

    Changing injector constant will change the fuel delivery "everywhere." If the engine is not tuned properly before you change the constant there is slim chance the constant alone will fix all the issues. You need to address the specific portions of your calibration that are not correct for your engine. If your engine is far from stock then this process takes time and will likely require many steps to complete.

    I cannot help with cell trace as I have never used it. I log data, stop vehicle, review data, determine what needs to be changed then make the changes.

    Closed loop enable and disable temperature are in most definition files. But the engine shouldn't get cold enough to disable closed loop. What temp does it cool to according to scantool? Have you confirmed temp is close to accurate?

    If cooling is valid there are a few easy checks. Do you have a heater core attached? If so, are you using a fitting with a restriction in the manifold? Excess flow could allow unintended cooling. Also ensure T-stat is closing fully and that you do not use the old trick of drilling a 3/16" or 1/8" hole through it. 1/16" is more than enough to bleed out air without excess cooling.

  3. #3
    Fuel Injected!
    Join Date
    Nov 2016
    Posts
    38
    Thanks, sorry I didn't reply sooner. So a lot has changed. I found out my thermostat was junk. it was a $15 Mr. gasket high flow gimmick product, it doesn't close all the way leaking cold water to the engine and not allowing the engine to stay warm when driving. So I replaced with a $4 thermostat that works great! Go figure. The next issue I found that the car will not cooperate unless I use a jumper wire on the ALDL diagnostic port from A to B as if I was pulling codes. I have to do this each time I start the car. If I don't the IAC is noisy, idle is high, engine runs rich the speedometer won't work and cell trace in tunerpro won't work. If I jump terminals A to B in about thirty seconds everything is working properly. I also got a code 51 So after that I ended up setting injector constants to 27lb injectors even though it actually has 32lb in the engine. The reason was if I set it for 32lb there isn't enough room to tune as my cell values would need to be above 99 to inject enough fuel at WOT. But with 27lb injector constant my VE cell values are in the low 90's at WOT. I was able to tune in OPEN LOOP only by going to scalars and adjusting 'Closed Loop enable, min temp' to the max value effectively disabling closed loop and running only in open loop.

  4. #4
    Fuel Injected!
    Join Date
    Nov 2016
    Posts
    38
    So I made it to dyno day and everything was running great, however the next time I drove it in Closed Loop it was way too lean! It was off the scale of my AEM UEGO wideband and undriveable. As of right now I can only drive it in Open Loop and it runs like a champ in Open Loop. Later that day my alternator quit and was replaced and then my plastic brake booster cracked causing a vacuum leak and no power brakes. I have a metal one on order. This stuff may not have anything to do with my tuning issues but I though I should mention it.

  5. #5
    Fuel Injected!
    Join Date
    Jun 2015
    Age
    29
    Posts
    263
    If closed loop is lean, but open loop is OK, suspect your oxygen sensor wiring or the sensor itself, OR you have an exhaust leak upstream of the sensor. O2 sensors do not measure fuel-they only measure oxygen.

    That means if you have an exhaust leak upstream of the sensor, it'll pull in some fresh air-which means the O2 sensor will see oxygen, and it will report lean-because as far as it knows, that oxygen made it through the combustion process and didn't get burned-so all the fuel was burned with leftover O2. LEAN! Except, of course, you're not really lean because the excess oxygen came in through the exhaust leak-not through the combustion chamber.

    False leans on the sensor would result in overfueling and the engine running rich, but reporting lean. This kind of thing can make you pull your hair out-so make sure you have no exhaust leaks up stream of the O2 sensor.

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