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Thread: Need info on what "TPS Out Of Range", QDM Fault, and INJ Fault is?

  1. #1
    Fuel Injected! twiztidditzwit's Avatar
    Join Date
    Oct 2020

    Need info on what "TPS Out Of Range", QDM Fault, and INJ Fault is?

    I have a 95 3.4l V6 that I've been tweaking. I am getting TPS Out Of Range: "YES" when accelerating but it switches back to "NO" when I am under TPS range and speed. It's hard to say what triggers it, but almost always will show "YES" when accelerating and at cruising speeds. I also Have QDM#3 showing a fault and INJ Fault = "YES" ALWAYS. I have yet to see the INJ fault bit and QDM#3 fault bit read "NO" Since I got the vehicle. I have DataCat for logging and I use TunerPro to modify my bin. I am currently experiencing lack of power and falls on it's face after it shifts (auto). I am also seeing LTFT be lean at upper rpm and load conditions, and rich when low load and rpm. I am fairly competent of my understanding of basic engine operation and what the ecu does its best to adjust and control, however, putting all of the information I am seeing into a logical diagnostic process is what I am only marginally capable of doing. I will be replacing timing chain and upper and lower intake and exhaust manifold gaskets within the next week or so. I would greatly appreciate any and all advice from the pros out there! Much thanks in advance! cheers
    1995 Chevy Camaro 3.4L V6 L32 "Carmen"

  2. #2
    Fuel Injected!
    Join Date
    Jul 2019
    Orange, CA
    You need to have a little understanding of what those items are actually talking about. For one, even though I am completely unfamiliar with your application, I am going to assume that "TPS Out of Range" is not an actual DTC but is rather a status message in your logging program. Rather than meaning "The Throttle Position Sensor is reporting a value that it should not," I believe this is actually saying, "The current position of the throttle position sensor is not allowing this other function to activate." To try to put this more simply, it's not just "TPS Out of Range," it's "TPS Out of Range [therefore enabling/disabling a specific function]." Again, I do not know your application at all, so I don't know what that would actually be. Torque Converter Lockup? CCP purge cycle? EGR? Heck if I know. But if it's not a DTC, then it's likely just a normal status message and can be safely ignored.

    Similarly, you need to understand that the QDMs are not error messages. They are used for internal diagnostics, and unless you fully understand what they are, they will likely lead you astray. The PCM in your '95 Camaro V6 was not unique to the '95 Camaro V6. It was also used in many other vehicles, not all of which were V6. Thus, if you're getting an injector error on one of the QDMs, I would likely posit that it's throwing that error due to the injectors for the V8 being missing. I can say this because, for example, on my '94 Corvette the QDM throws an error for the Transmission Performance LED. This is because the '94 Corvette does not have any such LED. It is normal, which is why that error is not actually enabled in the BIN. But the QDM will show all 'errors', even if they're completely inapplicable to your particular application.

    So yeah. I'm willing to bet that all of the "errors" you found are in fact totally normal and completely unrelated to the actual problem you're hunting down.

    As for solving your problem...well, I've never dealt with a '95 Camaro V6, so I can't give you any specific help there. Perhaps using Trimalyzer to analyze closed-loop datalogs and provide suggestions on how to adjust your VE tables? That's how it's done on our V8s, so I'm sure it'll work for a V6 too.
    1990 Corvette (Manual)
    1994 Corvette (Automatic)
    1995 Corvette (Manual)

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