JVasser

Today my buddy (a 2013 Race Red GT/CS) and I ( 2011 Yellow Blaze Base GT w/Brembo pkg) met up and drove Angeles Crest Hwy.

Awesome drive! He GoPro'd it and its on YouTube I'll have to see if I can link it.

About halfway up the mountain , the CEL starts to flash, then goes out. We stop for pics and to regroup and I lead off. About halfway into that run I notice that the light came on and stayed on. We got back to his place in Riverside and tried to check the code but the scanner said " No DTC codes to read". But the light was on plain as day. I decided to push my luck and came home Ortega Hwy.

Before I left I topped off and when I restarted the car, the light was gone! Coming across Ortega there were a lot of cars and I really didn't get to stretch its legs to much, but it did flash at me again and disappear.

When it was just flashing it was sustained RPM over 3k in 4th gear. To get it out of that window but still be "spirited" enough to get into and out of the corners I snapped it into 5th. Saw 2500 RPM to 4500 - ? RPM. The car was a tick warm, the outside air temp was 98 - 106F today depending on what side of the mountain we were on.

Mods to the car are K&N drop in filter, Pypes 3 in X pipe, resonator delete, universal Magnaflow 3in center in center out mufflers. No tune, nothing else...

It did this a couple of weeks ago but the light stayed on. Took it in for oil change, inspection and service and the rep said it was an intermittent mid fire and an intermittent misfire in number 6...

When I get on it now it smells hot, like cooking metal and something else... Cats going bad?

I'm the third owner of this car and had to repair an absolutely butchered exhaust to get to this point. Did the previous owners screw up my cats too?

JVasser

The video of us today...

2012GT

X pipe / no tune = culprit. Tune the car.

texastboneking

I dont think thays the issue... x pipes dont cause missfires. They cause the rear o2 sensors to set cat codes...

How many miles on the car?

mfc133

If you notice the misfire codes are being thrown for random/different cylinders it's probably an issue with the CKP sensor. Either needs a crank position relearn or the CKP sensor could be faulty. If the misfire always follows one cylinder it could be a bad coil.

2012GT

Yea but he's had shotty stuff done to the exhaust before he owned it. I think he should do a factory stock flash by the dealer and have an SCT tune (by a reputable tuner of course with his mods programmed waiting soon as he pulled out the dealer shop on his tuner). Install and I guarantee his car will be a beast unless there is something wrong with the car. The dealer could possibly check that depending on the dealer and their "mod" friendliness.

2012GT

Or a #8!!!! Jk

Cobrakev

Had same issues in my 13GT. They ended up changing the Crank Position Sensor. Haven't seen the light since.

JVasser

Thanks guys! It just turned 35,000 miles on the way into work this afternoon.

I pulled the codes with a different scanner on my lunch break tonight and got;

P0300 random misfire
P0301 cylinder 1 misfire (first time)
P0306 cylinder 6 misfire ( second time)

The light went away after about the 4th or 5th key cycle, but the codes were still there. I erased everything and will see if it does it again.

What kind of cost am I looking at for a CKP sensor re flash or replacement? I've been kind of eyeing the accel coils for a while now too...

mfc133

You mentioned the previous owner butchered the exhaust install. Might want to check the wiring harness for the CKP sensor was not damaged/is not resting on exhaust.

Technically you're still within your powertrain warranty but you may have limited success with that since you've got aftermarket exhaust.

LagunaBeach

With random misfires it is usually the crank sensor (make sure they do the end-of-line relearn on it after changing) or one of the cats is breaking up inside.

JVasser

Thanks guys... This sounds like it might be the culprit. I let them sell me on the gap insurance AND the extended warranty... But since I messed around with the exhaust it may forgo them both. Hmmm. When I had it in for the oil change and inspection the S.A. Told me it may be related to the aftermarket exhaust... Meh...

The Magna flows have to make some crazy turns to get into and out of the muffler. It's really quiet sometimes, almost quieter than stock. But it's a straight through muffler and 3in so...? I want something a bit louder anyway. I got the X and the muffs from Craigslist out her for $190 (for both) and couldn't pass it up. Ah well, do it once, do it right.

If it pops again and it's the same code I'll go ask for the crank sensor to get checked and serviced.

Thanks again guys!

GrabberBlue5.0

Is the x-pipe off road or is it an x-pipe after the cats?

JVasser

After cats, I took the car in to have it installed and the ball and socket flange leaked beyond repair so they installed a classic flat flange.

Took the car up to a buddy's hous in Big Bear yesterday for the 4th. Didn't hiccup or anything. The guys came out to look at the car and asked to hear it and then asked me to rev it a bit. When I rev'd it the light came on ansd stayed on. It went out tonight after I dropped off my daughter. So Monday ill throw it on the scanner again and see what it says...

FYI, I need a louder free-er flowing exhaust. A dude with a turbo'd 2276 cc Meyer Manx stopped by and that thing sounded like it had way more ***** than my car...