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My 2013 5.0 is starting to throw random misfire, misfire within first 1000 revs and 7 and 8 misfire. It was initially a cylinder 7 misfire the past couple of weeks, on and off, with the other codes. Only today did it actually start running rough. Truck has 179xxx on the clock. My first thought is the intake valve wear problem but I have yet to do a cylinder compression and a leak down test. I plan on running my scanner tomorrow to make sure the O2 on that side is working correctly. I don’t think the MAF would cause misfire on part of one bank. Is there anything else that I should really be looking at? It may also be a head gasket on that side as I’m having a coolant odor and some amount of coolant is disappearing as well……
The scanner is a good place to start. With so many things potentially responsible for the misfire checking for things in or near spec could save you a lot of work.
Have you looked under the truck for signs of coolant? When I bought my 2014 5.0 there were 60,000 miles on it and the water pump was junk. Plus a lot of evidence that there had been previous work on the water pump.
A water pump would be preferable to a head gasket!
I have zero visible coolant leaks. I did have the heater hose fitting blow out a while back and dumped coolant everywhere. I thought that was cleaned up but maybe residual odor? The other fittings have been fixed already and the water pump changed. About to hit it with the scan tool.
This truck is crazy. My son has been driving it so all this issue has happened since he has had it. It absolutely drives and runs like normal. I can’t detect any hint of a misfire. O2 sensors are working and within spec. Fuel trims are within 1% of each other between banks and the long term is at +/- 5%.
it just has permanent codes for random misfire and 7 and 8 misfire.
With the more recent 8 misfire and the unexplained coolant loss, I’m leaning towards a head gasket. Pressure check is next
Still going to put air into the cylinder to confirm but based on the color of the oil and the pressure and fuel type odor in the degas bottle, I’m leaning heavily towards a head gasket. Also been noticing a bubbling/gurgling from the heater core after acceleration. That probably should have been my
clue, even after the coolant was topped off it did that… IF it is in fact that, due to mileage, I’m going to pull both heads and check the valves and freshen the gaskets and bolts, timing chain and tensioners and cam sensors. I’ll keep the post updated.
UPDATE:
Tuliped intake valves in the 7 & 8 cylinder. That was the main culprit and there was a small head gasket leak between same cylinders. Head and block checked straight. Got new Melling intake valves so I’m going to lightly lap them all back in and put it back together. Got a new Melling high volume oil pump and new timing parts to go in it. #8 recessed in quite a bit Mostly normal #6 valves seated. #7 becoming recessed and worn
#8 valve that was recessed in the most. Note the razor edge that is not supposed to be like that. Fairly normal wear on this valve as compared to the #8 valve.
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