Code PO300

thegrays

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So start from the beginning, sent truck into dealership for new cv boots the technician tapped into the ecu seeing that I have tuned the vehicle. Following that they revoked the vehicles extended warranty. I did not know if they tampered with the ecu so I reinstalled the tune. About 2 hours later was doing a highway pull on 93economy 5 star tune then right after the shift from 3rd-4th WOT the cel began to flash and I read my monitor and it read PO300 random/multiple engine misfires bank 1.
I’ve done countless pulls on this tune with no issues but this time right after I picked it up from dealership it threw that code at me. The engine runs great I don’t recognize any abnormal noises than before. It still starts up first crank doesn’t sputter at idle and even during the wot pull it didn’t feel like I experienced a power loss nor did it make any foreign noise. Need some help if this code is false alarm or a real threat. The only engine issue I am and have been experiencing far before the CEL came on was an intermittent idle shake, assuming that it is in fact coming from the engine.
Here are my current mods
S&B CAI
stainless works LTH 1-7/8 with high flow catted mid pipes ( I have a slight leak right before the cat, on the clamp, on the right cylinder bank)
Corsa extreme catback
5 star tunes
 

Nex

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Did the dealership happen to flash your PCM while it was there? Might need a revision on your tune.

How old are your spark plugs?
 

thatJeepguy

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What dealer? Did you return to stock and drive around prior? Did you call 5 star and have them account for it?
 

thatJeepguy

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P0300 is random cylinder misfire. P0301 is cylinder 1 misfire. How many miles on the truck/tune? Spark plugs wear much faster with a tune, I would start there.
Can they really void yr warranty ESP in the system just like that?
 

FordTechOne

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Can they really void yr warranty ESP in the system just like that?
If you have an aftermarket calibration? Of course. Manufacturers only warranty what they build and validate. An aftermarket calibration can induce a multitude of failure modes; and that includes not only the engine but the entire driveline.
 
OP
OP
thegrays

thegrays

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Did the dealership happen to flash your PCM while it was there? Might need a revision on your tune.

How old are your spark plugs?
They did flash the pcm that’s how they figured out it was tampered then revoked it, the monitor was unplugged from the obd11, I re installed the tune again just to make sure then did a pull and the code popped up
 
OP
OP
thegrays

thegrays

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P0300 is random cylinder misfire. P0301 is cylinder 1 misfire. How many miles on the truck/tune? Spark plugs wear much faster with a tune, I would start there.
79k miles on the truck. With tune about 10k miles with it. I assumed it was the spark plugs was going to get the top 8 replaced soon might go with ngk plugs might go with factory.
 
OP
OP
thegrays

thegrays

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P0300 is random cylinder misfire. P0301 is cylinder 1 misfire. How many miles on the truck/tune? Spark plugs wear much faster with a tune, I would start there.
Would like an analysis over the misfire code, also the engine just said low oil pressure at idle shortly after beginning driving this happened right after I attempted to steer. The wheel locked up. Then I turned off the truck first crank it died immediately. Second crank it started up how it normally would’ve.
 
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