Hi all,
Yet another misfire thread, but this one has me stumped as the car idles fine and starts fine even on the coldest of mornings. My e53 3.0 with 100k miles misfires under load at wot. Particularly on a hill, but sometimes on even ground also.
I have changed the plugs and swapped around the coil packs and initially it was only cylinder 6 misfire. At that point I could not even get it up to highway speed without misfiring.
I cleaned the MAF sensor and threw some techron fuel injector cleaner in the tank and that made it better for a while, as in I could now reach highway speeds. I did not realize being on an incline makes such a difference triggering it, so I just drove around town and on level freeways around the house and everything seemed to be fine. Fast forward another couple of weeks and as soon as I hit an incline on the highway it would misfire.
New MAF sensor, new DISA valve, new oil separator and return hoses. New intake boot. Cleaned ICV, Throttle Body, air distribution piece with new o-rings. Took it for a test drive and took it up to redline and it did not misfire. I was so happy!
But as soon as I came up on an incline on the highway and opened the throttle, it misfired again. As soon as I exited the freeway and hit a stop light the misfire stopped and the "Service Engine Soon" light went off (usually I'd have to shut it off and restart it for the light to go away and the cycle to restart). This time my basic code reader detected a misfire on cylinder 4.
What should my next step be? The only thing that seemed to make it better was the bottle of Techron and cleaning the MAF initially because that improved it enough to bring it up to highway speeds again, but not enough improvement to stop it from misfiring under load on an incline. Now that I replaced the MAF with a new one, my guess is it was the Techron that was responsible for that initial improvement. Not sure if I'm overestimating the difference the Techron might have made. The car runs and drives great otherwise.
Am I missing something here? Thanks in advance for any suggestions.
03-24-2015, 11:25 AM
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