CEL........

[Condor1970]

- 800 miles, I get the tick.

- 1,000 miles. First oil change. Mobil 1 5w20 EP. Tick gets worse.

- 3,300 miles. New clutch installed. Now I have tick and rattle on 2,000rpm decel.

- 3,400 miles, switch to PUP 5w30. Tick still there, even louder.

- 3,500 miles, added 100ml Ceratec. Tick heavily subdued, but still there.

- 4, 200 miles. Today...CHECK ENGINE LIGHT!!!

Now what?!?!?!

I really love this car, but it's like the one favorite child in your family that insists on constantly ticking you off.

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[Condor1970]

Hooked up the Memoscan this morning. CEL is off now, but still in memory. P0300 random/multiple cylinder misfire.

I have a feeling it "could" be the gas. I ran 87 octane for a couple weeks, just to see how it would behave for commuting. 87 seems OK for commuting, but nothing else. It feels/sounds a "little" rougher and not as much power when accelerating.
At 1/4 tank, I decided to switch back to 92 octane, so the combined is about 90 octane right now. I revved up to 6,000 rpm yesterday getting onto the highway, and drove in 5th gear for a while to run in the engine at 2,500rpm for a bit. Oil and coolant temps were good, with head temp peaking at 214F. That's when I noticed the CEL.

Even though the CEL light is off, I'll still take it in Monday and let them clear the code under warranty.

 

[Condor1970]

Took it to the dealer. Random misfire, P0300. Probably cheap gas from Costco.

 

[AlphaCoyote]

Did you do a crank relearn after installing the new clutch?

 

[Condor1970]

Did you do a crank relearn after installing the new clutch?

He said it may have had something to do with that, but wasn't sure if that was the cause or not. So he did it again just to make sure. That said, I still buy all my gas from Costco, but I'm sticking to 92 Octane from now on.

"P0300. Inspected Mode 6 Data, found slight misfire counts on multiple cylinders. Performed misfire test, found all normal at this time. Performed Natural Profile Relearn. Found no further issues."

 

[2015V6Fla]

- 800 miles, I get the tick.

- 1,000 miles. First oil change. Mobil 1 5w20 EP. Tick gets worse.

- 3,300 miles. New clutch installed. Now I have tick and rattle on 2,000rpm decel.

- 3,400 miles, switch to PUP 5w30. Tick still there, even louder.

- 3,500 miles, added 100ml Ceratec. Tick heavily subdued, but still there.

- 4, 200 miles. Today...CHECK ENGINE LIGHT!!!

Now what?!?!?!

I really love this car, but it's like the one favorite child in your family that insists on constantly ticking you off.

Take a look at this thread:
https://www.mustang6g.com/forums/threads/first-problem-2016-gt-surging-p0308.112957/

This concerns the P0308 CEL code that's similar to your P0300...

 

[Bob D]

2017 Mustang GT 5.0 the check engine light comes on buy gas and light goes out then in like 15 miles back on?

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