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Thread: Missing misfire counters and fuel trims always 0

  1. #1
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    Missing misfire counters and fuel trims always 0

    I have a 2007 Dodge Caliber R/T race car that I've supercharged and campaign in the 24 Hours of Lemons racing series. The car was tuned with HP Tuners and up until last week was running quite well.

    The car developed a serious misfire that we cannot track down. We were getting some crank sensor codes, but those have gone away. We now just get cylinder 1 misfire code and no other codes. We've swapped injectors, coils, plugs, etc. Our next step is to check fuel pump pressure and look for a vacuum leak.

    During troubleshooting, I discovered that the fuel trims are always 0 and that I cannot find the misfire counters. I'm not sure if the car always had 0 fuel trims and no misfire counters, or if it was a side effect of the engine tune, or a recent development? Does anyone else know what could cause this or how to fix it?

    Thanks!!!

    Screenshot 2024-04-30 at 1.10.39 PM.jpg
    Last edited by ErrorMargin; 1 Week Ago at 08:14 AM.

  2. #2
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    Here is a log and my engine tune.

    test run April 28.hpl

    Caliber Tune SC April 28 2024.hpt

  3. #3
    Senior Tuner edcmat-l1's Avatar
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    You have an O2 sensor code. Might be why it won't go into closed loop.

    I don't have an answer for your misfire counters. do you know how to add a channel? They won't automatically show up in your channel, or pid list. You have to add them.

    As for the misfire on cylinder 1, you need to do a compression and leak down test. Because it's supercharged it's more likely to hurt a piston.

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  4. #4
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    Quote Originally Posted by edcmat-l1 View Post
    You have an O2 sensor code. Might be why it won't go into closed loop.

    I don't have an answer for your misfire counters. do you know how to add a channel? They won't automatically show up in your channel, or pid list. You have to add them.

    As for the misfire on cylinder 1, you need to do a compression and leak down test. Because it's supercharged it's more likely to hurt a piston.
    We've had the downstream CAT 02 sensor disconnected for a few years with no issues (there is no cat).

    In the next few days we will inspect all engine harness connectors, check fuel pressure, compression, look for vacuum leaks and look at the waveforms on the coils, injectors and sensors with an oscilloscope.

    How do I add a channel?

  5. #5
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    right click : )

  6. #6
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    Quote Originally Posted by LilSick View Post
    right click : )
    Ok, I see that and did that. There were no misfire counters in the list.

    It only had a "Monitor Status: Misfire (SAE)" but when I added that it displayed "Not Enabled"

    How do I enable it?

    Again, I'm pretty sure my car should have misfire counters because I've seen it on other Dodge Calibers.

  7. #7
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    I thought you had Sean Church tune that car?

  8. #8
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    Quote Originally Posted by ErrorMargin View Post
    The car was tuned with HP Tuners and up until last week was running quite well.

    The car developed a serious misfire that we cannot track down.
    It turned out to be a bad ECU....

    Here are the symptoms I had:

    P0300 Random Misfire
    P0301 Cylinder 1 Misfire
    P0304 Cylinder 4 Misfire
    Rough running
    Very low power
    Flashing check engine light
    Using my Autel OBD scanner, the computer was showing 31.54 inHg at idle (obviously implausible), but my analog vacuum/boost gauge showed 14 inHg

    Here is what I tried to find the issue:

    Swapped coils
    Swapped spark plugs
    Swapped injectors
    Swapped MAP sensor
    Swapped crank sensor
    Looked for vacuum leaks
    Checked engine bay ground points
    Compression Test (185 to 191 psi on all cylinders)
    Tested coil and injector harnesses for continuity to ECU, no cross talk, etc.
    Fuel pump pressure test (58 PSI, this is in spec)
    Visually inspected engine harness and all connectors for damage and corrosion
    Thoroughly cleaned all engine harness connectors with electrical contact cleaner

    None of that worked.

    We did not know what else to try, so we bought a remanufactured ECU from ARES Technologies. I put the ECU in the car, flashed it with our tune using HP Tuners and it solved the problem.

    I drove the car for an hour yesterday. It ran great and no CEL! Just in time too...I race at Thunderhill in a few weeks.

    Still no misfire tables. I am open to suggestions on how to enable them.
    Last edited by ErrorMargin; 1 Week Ago at 08:29 PM.

  9. #9
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    Quote Originally Posted by LilSick View Post
    I thought you had Sean Church tune that car?
    Yes, he did. I have over 15 hours on the track with his tune in the car and could not be more satisfied.

    He did a great job, the car runs strong and does not overheat.

    I highly recommend Shawn Church.

    Attachment 146085