I've been fighting an ever lasting fight against P0300 and evident misfires.

Sequence

6 weeks ago - installed new BPR8ES plugs, 20 miles later misfire
4 weeks ago - installed new BPR7ES plugs, 15 miles later misfire
Last week - installed new OEM plugs, 40 miles later misfire
Monday - installed new BR7ES plugs, 12 miles later misfire.

Everything was gapped at .025 and I'm running stock coils. I have tried a different coil set and still no dice. Should I consider dropping the gap to .024 or smaller?

Mods:
Stock Intake Tube with Green Filter
HKS 272 Cams
Hallman MBC, currently set at lowest boost setting so it's running off WG pressure.
3" DP>Milspec Cat>3"exhaust
BR UICP>Evo X Bov>Pruven FMIC>Nisei LICP

 

When does the code trigger?? Idle?? Highway speed?? What do the ignition/fuel maps look like?? What year car?? If 03-04 what rom is it on??

 

Check the cam sensor.

 

If this is happening on the highway while cruising simply disable the p0300 code. I have done it years ago and never had any issues.

If it is happening at idle or you are throwing other codes it needs to be figured out and not simply disabled.

 

It usually only happens at highway speeds and when it does happen the car runs like poop.

It's an 03 running on a very old Dynoflash map. That in itself speaks volumes, but a tune is a tax return gift for myself. I never thought about the cam sensor, but I will do some searching.

 

At highway speeds your looking at the classic 03-04 P0300

Mitsu's answer was drivetrain harmonics and supposed fix was two ROM updates 0014 then 0015. I'd say if an 0015 ROM does not fix your issue just disable the code routine

 

Gap to 0.020 and try again.
If that doesn't correct then disable the code as others have said (for highway occurances)

 

I'm 110% sure I don't have either of those ROMs. I'll try making the gap on the plugs smaller and see if that helps.

FWIW I'm running an Exedy Twin disk and that ****er makes a TON of noise.

Hopefully a COP will help with some of this.

 

Keep in mind what everyone just said. It isn't necessarily ignition related so spending 400+ on a COP until you're over 550hp is not necessary. Having twin/triple disk clutches doesn't help the issue but neither does throwing money on unnecessary parts. A flash to bring you current will most likely resolve your issue. Contact tscompusa on the forums, he's a well known and respected tuner who may be able to touch up the issue at a minimal price

 

Just curious, but are you the second...3rd... 4th owner of this car? And how many miles are on it?

 

0008 ROM is what they left the factory with. Don't spend money on any other ignition related components man. I would get it on a 0015 ROM and have your fuel and ignition tables tuned correctly, your ignition map prob looks like this:

88888888888888888888888888888888888888888888888888 88888888888888888888888888888888888888888888888888 88888888888888888888888888888888888888888888888888 88888888888888888888888888888888888888888888888888 88888888888888888888888888888888888888888888888888 88888888888888888888888888888888888888888888888888 88888888888888888888888888888888888888888888888888 8888888888888888888888888888888888888888



From there if the issue still remains disable the code routine.

 

I'm the second owner of the car, it has 63K miles on it. Maintenance is up to date. All the major mods were done by the prior owners, an older couple...bought it from them 3 months ago. I personally would not have opted for the Exedy Twin Disk based on the sheer amount of noise it makes.

I'm more concerned with improving basic driveability.

As for the COP, I have a custom one made already, but I want to make sure I fight this gremlin first instead of relying on another part to mask the symptom.

 

For starters get rid of that tune ASAP then use the patch to turn off the P0300 code.

This is an endemic problem with early 8's and has been completely solved for years now. Search the ECUflash forum for all your answers.

There are many reasons why P0300 happens, often sh1tty timing jumps in your mapping, random mech noise, etc.

 

I'm somewhat familiar with the "sea of 8s" tuning methods in the early years of the platform. Yes a tune would alleviate much of problems I'm sure, but it's not something I will invest at least until post xmas.

So I'm hoping to alleviate the issue as much as I can using conventional methods (for an unconventional car). I am removing the Hallman MBC and installing the stock boost lines for safety reason. I for the most part have stayed out of boost as I'm afraid of wrecking my ****.

On the flip side I'vw acquired a plethora of plugs in near new condition!!!

 

So you ask for advice, get an answer and decide to continue doing what has not been working? GL.