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I was on my last session last weekend at COTA and noticed the car sounding different than before. The exhaust sounded like it was rattling a little loose, and it sounded rougher than normal. On the way home a CEL popped up on the dash but the car is not in limp mode. Code P0430 - which is "Catalyst System Efficiency Below Threshold Bank 2"
I cleared the code (and it returned after a short drive), put the car up in the air and double checked all clamps, and checked for exhaust leaks and all is well. The car is completely stock but the track conditions were pretty brutal (really bumpy, 94 degrees, and humid) so it was pretty hard on the car.
When I started it up this morning, I could instantly hear something was off. It sounds almost WRX-ish with a bassy pulse. I drove it around the block and noticed the rough exhaust sound and there isn't a noticeable 4k rpms transition with the valves either although I know for certain they're connected.
Here's a short video on the exhaust noise at idle. You can hear the pulses which aren't normal from what I remember.
My questions are:
1.) Has anyone broken a catalyst/header before on these cars? I'm thinking maybe the core is broken internally if possible.
2.) Are the headers/cats covered under emissions warranty?
3.) Could this be a sign of a terminal engine issue with the .1 engine? I've heard of the car popping a CEL and going into limp home mode when that usually happens, but not sure about this one. Typically I hear the WRX noise out of an exhaust, it's a sign of low compression in a cylinder, or bad coil pack. The car feels pretty normal and doesn't smoke fortunately.
I have an appointment Thursday with the dealer here in town to see what's going on. Hopefully it's something that's covered under emissions or the 10/120k warranty, or worst case an excuse for a Dundon header setup
I'll follow up with the diagnosis and fix in case any others experience this.
Sounds like a broken exhaust valve. You do have an 8/80k emissions warranty on cats, but each annual service is a required service so if those were not done they could technically deny it.
Thanks guys. I checked both exhaust valves, and was able to move the actuators freely. I then videoed each one and they're both moving when I press the button on/off so I'm afraid my issues may be more upstream.
Update: Drove it around today to see if messing with the actuators fixed the issue. It definitely did not. I tried to roll on the throttle to see if I felt a loss of power (I did), but as I was winding it up to 9k, I got code P0304 (Cylinder #4 Misfire) and the car went into Reduced Power Mode. I'm parking it until its appointment Thursday, but the misfire CEL makes me think something is wrong with the motor itself. Maybe I'm "lucky" and have a G series motor in my future, or maybe it's just a causation from a bad catalytic converter. I'll update this as I find out more.
On the bright side, maybe it’s just a spark plug or coil pack- both can be short lived on these cars. But if you’re hoping for a new motor, maybe that wouldn’t be the bright side
On the bright side, maybe it’s just a spark plug or coil pack- both can be short lived on these cars. But if you’re hoping for a new motor, maybe that wouldn’t be the bright side
Hey I'm happy either way as long as I can get it back 100% asap. It's too fun of a car to let sit broken.
Originally Posted by usctrojanGT3
Maybe it's bad gas?
I was running about 50/50 unleaded 101 and 93 at the track since it was so swampy outside as an extra precautionary measure. I wouldn't think it would cause the rough exhaust sound throughout the rev range, but anything is possible. Maybe I did more harm than good...
Originally Posted by Alan C.
Had that once and it was a plug/coil pac. Replaced and the problem went away.
That's comforting to hear. It's only a little over 2k miles away from needing plugs anyway. Only thing is I've had a coil pack die on my M3 and it was a lot more obvious and underpowered. Hope you're right though. I'll take a bad plug/coil pack over bad cats or an engine any day.
It's been 3, going on 4 weeks now. According to the dealer they've replaced the #4 coil pack, secondary air pump, cleaned the ports, pulled the exhaust manifolds off, checked the cats and now determined one of the catalytic converters are bad. The concern is that catalyst material has found their way into the ports, thus damaging the combustion chambers/valves.
They've been in contact with PMNA and now the next step is to drop the motor, inspect the heads, ports, etc.
Is it weird that I feel like they're sort of stringing along PMNA for labor/time costs instead of just replacing it with a G series motor? I mean it did have misfires early on but it just seems like they're exhausting every possibility emissions-wise before they'll inevitably replace the motor. Worst case they disassemble/reassemble it and I still have a motor that's not 100%.
I dunno. Seems like other .1 GT3 owners didn't have to go through all of this hemm & hawing to get a new motor and be done with it. Starting to 2nd guess this purchase when my heavily tracked M3 never gave me this much trouble in its 160k miles.
Update: Got word from my dealer that a new engine was approved and it should show up in the next week or two. The theory was that catalyst bits scored the cylinder walls of cylinder 4, but my gut tells me it was still the finger follower/rocker arm issue as the root cause. Can't wait to get back into this thing! Hopefully other owners won't encounter this but if they do maybe this thread will help.
In the meantime I got to take a peek at the engine bay while the motor is out (reposted from another thread):
05-26-2019, 02:01 PM
Code P0430 & Rough exhaust sound. Anyone break a catalytic converter before?
