Misfire or Load Limiter?
Misfire or Load Limiter?
Haven't driven the car awhile until just lately. When I stepped on it, I get heavy misfire when the turbo gets into boost.
Checking the logs, I see a steady 2-byte load of 159.375 at 100% TPS and never more or less. AFR is fine and knock count is zero.
Ordinarily I'd look at the plugs first, but that unwavering 159.375 looks suspiciously like a load limiter of some type as opposed to misfire. Now, I've been tweaking things like ISC steps and such, but I haven't touched the limits. I've rechecked everything, and it all looks square - all limits with disabling values. Reflashing with slightly earlier programs had no effect. I checked for boost leaks not long ago, but I'll redo it.
So, is it the plugs, massive boost leak, or is there a ghost in the machine (ECU)? Hedge your bets.
Checking the logs, I see a steady 2-byte load of 159.375 at 100% TPS and never more or less. AFR is fine and knock count is zero.
Ordinarily I'd look at the plugs first, but that unwavering 159.375 looks suspiciously like a load limiter of some type as opposed to misfire. Now, I've been tweaking things like ISC steps and such, but I haven't touched the limits. I've rechecked everything, and it all looks square - all limits with disabling values. Reflashing with slightly earlier programs had no effect. I checked for boost leaks not long ago, but I'll redo it.
So, is it the plugs, massive boost leak, or is there a ghost in the machine (ECU)? Hedge your bets.
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Are you suggesting a glitch in the program? I've tried several known good ones, all with the same result. This problem just seemed to pop up out of nowhere. I can't imagine what would have triggered it.
I'm suggesting that you are only logging 1-byte airflow, like the issue with your load log originally.
The limit for 1-byte airflow is somewhere around 1600Hz. If you want to log above that, then you need to log 2-byte airflow. In order to do that, you need the correct addresses for your ROM setup in the MUT requests that you are logging with EvoScan (or whatever logging tool your are using).
I believe EvoScan is setup to look at 2 particular MUT requests for 2-byte airflow (I forgot if it's 2+3 or 4+5), but you need to ensure that the correct variables are in your MUT table if you want to log 2-byte airflow.
The limit for 1-byte airflow is somewhere around 1600Hz. If you want to log above that, then you need to log 2-byte airflow. In order to do that, you need the correct addresses for your ROM setup in the MUT requests that you are logging with EvoScan (or whatever logging tool your are using).
I believe EvoScan is setup to look at 2 particular MUT requests for 2-byte airflow (I forgot if it's 2+3 or 4+5), but you need to ensure that the correct variables are in your MUT table if you want to log 2-byte airflow.
Last edited by l2r99gst; Apr 15, 2009 at 12:25 PM.
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