2015 5.0 sporadic IDLE, Air/Fuel Ratio Caused by Ghost Cam?

[SwankyStang]

Hey guys, last week out of the blue my coyote began having idle and drivability issues that has me stumped. After it settles down from the initial startup (warm or cold), the car begins bottoming out with rpm's fluctuating between 550-900. Along with that, the air-fuel ratio jumps in the matter of 1-2 seconds between 8.5 - 20 and has stuck several times at 14 or 20 in the middle of driving that's forced me to pull over and restart the car to return it to its fluctuating state. Engine braking still works above 2.2k but below that and the exhaust starts backfiring in the same 1-2sec way off and on. This seemed to have started the day I flashed my car back to the Lund flex fuel tune I use as my daily from the ghost cam I'd been running the previous night. Initially, I thought the tune might have been corrupted and tried flashing the vehicle back to stock but with the same problems. I read on another forum about a potential spark plug or injector issue so switched out the plugs yesterday (they were due for it anyway) and ran injector cleaner with almost an empty tank. Also inspected the MAF sensor and cleaned the intake filter but nothing changed. However, last night as I was trying to reach the cylinder #4 plug with the socket, I leaned on the vacuum hose going from the outlet closest to the oil cap leading to the intake (P# BR3E-6K817-CB-50342) and bent it slightly. This morning as I loosened that line, the car rpm's leveled out and ratios stayed within 5-7 which I'm guessing narrows it down to a vacuum issue? A couple of services advisors from the dealer mentioned a possible valve problem but I'm not willing to pay their $123/hr diagnosis fee if they don't really have an idea. I'll be meeting with their technician tomorrow that specializes in coyote engines and keep you posted but does anyone know of the steps to fix this?


Mods: MBRP off-road Headers w/ H pipe and axelback, K&N CAI, Lund Racing N Guage Tuner

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[SwankyStang]

So for more than a week I haven't been able to read a single code until I accidentally pressed "Read Vehicle" instead of "Read Codes" and lo and behold there's a p0155 for Bank 1 O2 sensor when I went back to look. Not sure if it was a glitch or what but it makes perfect sense for what's been going on. Will post results tomorrow after replacing it...

 

[Kong76]

I gotta ask, What did you use to get to the rear passenger side spark plug? the damn battery firewall is in the way and I gave up.

 

[SwankyStang]

I gotta ask, What did you use to get to the rear passenger side spark plug? the damn battery firewall is in the way and I gave up.

I used a standard 8in extension on the first 7 plugs but when it came to that one I had to run to the hardware store and pick up a 6in bendable socket extension. It ended up twisting up in a knot under torque so then tried dropping the plug socket in first, then the 8in extension, and actually hammer a small dent about 1/4in into the battery bay (unnoticeable with insulation there) so I could attach the socket. After the plug was unscrewed, I took out the extension and used the messed up bendable extension as a way to retrieve the plug socket. In all, that one plug took about an hour whereas the other 7 took a little more than that combined.

 

[SwankyStang]

After 3 different shops telling me things that really made no sense and around 6+ hours of their diagnosing time, I stuck to my gut and went ahead and replaced both O2's with oem Ford. FIXED IT. The ghost cam tuning the engine to run rich had degraded a sensor but had thrown off all techs due to nonfluctuating voltage in the leads and the pcm grounding the circuit. If anyone ever has an O2 code while running a Lund tune, be sure to FLASH THE STOCK TUNE. The Lund tune fights the pcm and won't revert to its hard readings of 14A/F ratio. The good sensor will continue compensating for the bad one causing those massive fluctuations. I was told it could be a mechanical problem with the valves, there was possibly metal in the oil, and even that I would need to reflash my pcm at ford as the tune may have altered some parameters and get a completely new tune! What a Sh** show for a sensor.

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