Overnight plunge in gas mileage.
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Overnight plunge in gas mileage.
Here is one that started a while back. I was driving thru deep water and truck died. Threw back multiple codes, mostly misfires and catalyst damaging misfires. This was attributed to faulty wires/coil pack. Got those changed and did new spark plugs (Bosch OE finewire Iridium, 7MM Bosch Plug wires and AB coil pack). Left the shop and truck ran beautifully. Plenty of power, no stumbling at idle, all seemed well. Until fill up time. Before this event I could rely on seeing 220 miles on the trip meter at half tank (mostly highway). After the ignition work I am lucky to see 160 at the half tank mark driving the identical route, this has been going on for several months now, was hoping it would sort itself out (duh). So now I'm left with tons of questions, did the tech leave something undone behind the manifold? Is a plug wire arcing? Could I have clogged a CAT during the misfire event (I had to limp it over 20 miles home after it finally started after puddle jumping). Did the O2 sensor (or 4) go tango uniform during the misfiring? Did I break a valve or piston ring during limp home? I know this must seem like paranoia, but the drop in economy is real, and dramatically lower than before the event. I've poked around in the computers, no codes. Monitored the ECU real time data with nothing appearing out of the ordinary. Any ideas what I could be missing? Anyone else ever see this situation before? Next step is selling and getting LR3, but I love my disco and really want to sort this out. Thanks in advance for the assist.
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O2 probes changed.
So the front O2 probes have been changed with new, while they were out I bore scoped the cats, both looked perfect. First tank of fuel yielded 13 mpg highway, not great but still an improvement. Going to replace the MAF sensor next, don't like the look of it, can't get the thing completely clean. Any other thoughts on this one?