Can any of you gurus help me out, I finally have my beast running somewhat smoothly, with the exception of one error code, the notorious P0300 - random/multiple cylinder misfire. From what I can gather, sounds like it happens pretty often with FI (from things like bouncing off the rev limiter). The car runs like a champ above 2K RPM, AF looks great, boost is good, no belt slipping. The only observable problem seems to be at idle, and not in drive (that's fine), but in park. When I put it in park, the idle fluctuates between 1200-1300 RPM and feels really shaky, there may even be some knock.

I'm suspecting either the tune, my plugs, or my injectors. Is it humanly possible for plugs to foul after ~6 months of use?

The only things that are new in the car are 600cc injectors (formerly rated at 650cc), 2.87 pulley, reflash, UTEC retune, and the GTM pulley mod.

P.S. if it looks like a typical case, I have a diagnostic scanner, I'll just clear the codes when they pop up.

 

Completely forgot about the MAF, good call, thanks. My plugs are NGK one step colder. Based on my zeitronix readout, AF at WOT looks like it's ~11.3 or so (may dip slightly below that, it happens so fast), AF at cruise (typically about 40 MPH for me, ~1600 RPM) is about 14.5-14.7. One thing to keep in mind is that I'm running 12 psi of boost at 6800 RPM, have a lot of backpressure.

EDIT: I think my tuner raised the idle significantly because of my belt tension, with my old setup (3.12 pulley, gates belt), the park idle was much lower (~950 RPM).

 

P0300 is normal especially on cold start and colder plugs.... I get them every now and then but only on cold start...

 

Thanks, I knew some of you guys had them occasionally. Emissions should be fun!

 

I get the opposite. Every now and then on hot starts.

 

Where do u live? As long as you don't have a code at the time of emissions you should be fine.

 

I'm in your neck of the woods. I can clear the code before the inspection, I don't know how the hell I'm gonna pass though, man my exhaust is bad, it's like that stench on an airplane when they fire up the engines and the cabin smells like burned kerosene for two minutes. May have to throw my stock cats back on, I have plenty of time though, no worries.

 

Where abouts? NOVA? If so u should come out to some of the meets/HH's. Go check out National G Club.

Had my emissions done in August 07 (w/out the turbo). All them do is plug into the port and start the car up.

 

I may have a couple of P0300 with hot start but I always get them when I'm starting the car.. especially when the car doesn't start right away in one click. Since the TestPipe install I haven't had any CEL...

 

I also get one misfire code evey now and then. On average about every two months apart I'd say... I just reset the code and I'm good for several weeks.

Good luck.

 

I get them from time to time now that my motor is built and I have RC 750's. From everything I have found it's not a big deal.

 

Wow, didn't realize it was so widespread!

6spG, I'm not really a car club guy, with the exception of driver. Getting too old and bitter.