Last weekend I installed a set of HKS 272's into my '03 VIII and took it for a quick log run. Found a lot of knock coming up, so I lowered timing and added fuel to bring it back to safe levels (the most I was getting was 1-2 counts). Fast forward a week and this is what I've been getting: Day 1 on the new reflash was great...no knock and no problems. After a couple days I noticed my cel light start flashing (knock cel mod) at the typical transition point from vacuum to boost like it used to do. Now today the cel light has been going nuts at that transition point and will flash the cel light every time I go into boost. On top of it all I'm now getting a p0300 code every time I drive the car. Most people say it doesn't affect performance, but for some reason on mine it does...my AFR's changed completely from what they should be and go extremely lean every time this code is set. If I clear it, it stays off for a little while and the car runs normal with the proper fuel/timing. Nothing like being at 20psi with a 13.3afr to make you all warm and fuzzy inside.

What can I do to get rid of this problem?

 

Try gapping the spark plugs to .022-.026. Also what helped for me was the Sun Auto HyperForce. Pretty much eliminated the P0300. Just my .02

 

Yeah, I'm going to try a new set of plugs tomorrow before I drive 2 hours to a car show and see how it does. I'm going to give the standard NGK BPR8ES plugs a shot instead this time, the Iridium plugs are just too expensive to justify a new set every 2-3 months.

 

I just pulled out the old plugs and they still look brand new with a gap of .028. I cleaned them off a little and gapped down to .024 to see if it makes a difference and reflashed again...I'm going to do a solid datalog on my 2 hour drive and see if I notice anything weird. According to the freeze frame from the code it was being thrown around 2500 rpm and between 20-30% load. Also the timing number listed was 43 degrees of advance (which is not in my map, only 38 at that point). There is a map that's sort of unknown what it's for (or at least I don't know what it's for, it's listed as some type of boost timing advance but only has advances in very low load sections) that I lowered all the timing numbers in, so maybe that'll make a difference too.

 

It sounds like you need to properly tune your fuel / ignition map to get rid of your P0300. At least some of the P0300 issues are directly related to the tune. You should examine the freeze frame data that goes along with the dtc to find out the conditions when the code was set. If your 13.3 @ 20psi, your issue is likely with your fuel map.

However, there are alledgedly cars that have correct ignition / fueling and still throwing P0300's. P0300's can also be linked to mechanical failure or wear (ex. injector, plugs, wires, coils), boost leaks, etc.

 

That's the issue...the freeze frame data points to low load/low rpm, usually around 2500-3000rpm and 45-65% load. My fuel map at 20psi usually keeps the car at a nice safe 11.3-5 AFR until the p0300 code shows up...then it jumps to 13.3afr.

There is a table (probably incorrectly labeled too) called boost enhancement adv/ret that shows additional timing advance that gets added to the low load areas (probably for something related to the EGR system). Yesterday I took all those numbers listed in the table and cut them in half and so far it's worked well. For anyone who tends to get that annoying stutter hesitation from coming off the throttle and then back into it, try lowering these numbers because it removed the stutter from mine completely and I haven't seen the p0300 code yet and there are none pending either.

 

I was getting plauged by the P0300. Just at idleing situations then it hit me when I installed my cams be bumped idle timing consideably. I was also seeing knock in the areas you were explaining

I pulled out some timing in those cells and havent had a P0300 since (6 months). Im figuring the knock was coming on because of the big jump from where I had the timing to the rest of the map

 

That's pretty much what I was thinking too, the timing jump was just way too much and it probably did have a miss every once and a while. That's why I checked out my logs after seeing the freeze frame data that showed anywhere between 41-43 timing advance...no where on my timing map is there that much, only 38 at the most. After adjusting that "boost enhancement" table it dropped timing closer to normal and made the car run so much smoother now too. And so far so good, no p0300 as of yet.

 

Keep your fingers crossed. The ignition advance is need to keep from getting missfire during a slower burning CO2 rich charge at cruise. Hopefully the smaller gap might of helped.

Larger duration overlap mightdilute things and cause missfire too. Do a search for ignition maps for VIII PO 0300 fix ( I think bigric mentioned the exact cells in a post) if your problem comes back.

 

Thats sounds like the issue I have. What did you do to fix it? Was it the table? Is there a similar table in evo IX?

 

So far reducing the timing listed in that map (boost enhancement adv/ret 2) has worked wonderfully. Ever since I cut the timing in half on that map I haven't seen the p0300 and it seems to have smoothed out my part throttle/low load jerkiness that was pretty typical in the past.

Now if only there was a way to get rid of my knock as I cross into boost, it always does it on low load just as I slowly creep up to 0 in/hg.

 

slo did this fix the p0300 even during transition. I go into limp mode about 10 times a day. I have heard that it is everything from tranny harmonics to timming issues but noone has had an actual fix just cover ups. I think that this is the closest to a fix i have seen in a year. I hope that this will work for me to. I throw the code during cruise or at transition from neg to positive pressure. Fifth gear sees it constantly. Less on cold days and every 7-10 sec. on hot ones and is almost undrivable on the highway. If I release my foot from the gas it pops my bov and stops the shuddering until the next time (10 secs later). I have seen this issue since I had my cams gears and cams installed. I can not wait to get back from vacation and try this out!!!!

 

Keep me in the loop please. If you have a IX please let me know the name of the table I need to modify.

 

Ok, so far this is what I've noticed during logs and from looking at the freeze frame data when the code throws. I wanted to see if this really would be a "fix" or if it was just a once and a while issue so I reloaded my old map again to start from scratch and try individual changes at a time. Typically I was seeing the code come up after seeing the knock light staying on for a full 2 cycles (mine is set to 4 seconds of flashing, so after 8-10 seconds) and the knock would somehow trigger a misfire (sounded like a 3 cylinder burp) which would set the code. After the code came on, the car would run fine on all 4 cylinders except for leaning out like before and taking longer time to spool up. First I tried just to reduce the timing in the "boost timing adv/ret" map by half. It worked fairly well for about 3 days and the cel came back, once again as I crossed over from vacuum to boost around the 3000-3500 mark. Back to datalogging again, I noticed anywhere between 4-7 counts of knock starting near 80% load and extending usually to near 120%. I retarded the timing from that point forward and so far I've been going strong with no codes and none pending. Before I changed the "adv/ret" timing I was getting knock onset at 50% load, sometimes even earlier. I'm not sure what this map does, but I'm betting it's something to deal with timing for EGR. There is no reason why these motors need 46-48* timing advance at low load cruising, and with a larger cam set I'm willing to bet the EGR mixture gets changed quite a bit and starts the misfire, and therefore probably needs less timing advance to ignite the mixture.
Best thing I can say is so far it's worked for me, give it a shot and try it...if it doesn't cure your issues there's really no harm done. I'm also wondering if throwing this code disables lean spool, but I don't have any evidence to go along with it just yet.

 

mt057 I forgot to mention one other thing...make sure you're map is updated to the 94170015 version instead of the original 94170008 version...the updated version has some fix in the knock maps that helps with the p0300 problem.