From time to time I get the P300 code for multiple misfire. I have had the Sillen Stage 4 SC on my G35 for about 6-8 weeks. I did not have a problem until I installed a coolingmist h2O/meth kit and Kinetix HF cats. The coolingmist went on a couple days after the stage 4 (from stage 3) because I got some ping. The first time I saw the problem was the day I installed the coolingmist kit but I just disabled it. I just installed a new set of plugs and still have the problem so I doubt that is it. The H2O kit is off and I just got another flashing CEL tonight at WOT.

I am about to go re-check all my hoses but besides that I'm stumped. Could a tiny exhaust leak on the cats be causing it? My A/F is ~14.5 at idle and ~10.9 at WOT. I was thinking my fuel pressure may be to high/low but I don't have a gauge. Any other ideas?

Thanks for taking the time to read this and comment.

 

seriously i have that one all the time, who cares??? that lets me know everything is A OK!!

 

You get it all the time?

It makes me nervous but maybe it just comes with being FI. I had the Stillen SC for months with no problem but now that I have the stage 4 kit and water/meth these problems are occurring.

 

i really dont think that i have cleared the codes out and not seen a P0300. i made up my own diagnosis and i say that code means everything will be alright!!

 

Got it again today. This is starting to scare me...

 

I had three inch exhaust with no cats on my car and got that code all the time. I thought it might be the cams. I just put the stock cats and stock exhaust back on and guesss what, no codes.

 

the P0300 is my friend. My dash is lonely without him

 

 

and going FI damn near changes all those possible causes

 

Tim, remember that night I called you and told you that I had the CEL light come on? Well, I took it to Autozone and they said that the code pulled was the P0300 as well. "multiple engine misfire". Do you remember what I said that I was doing that was causing the code to show? I was sitting in my drive way trying to figure out the belt squeal and I was holding my RPMS around 2.5k for a good 10 seconds and then I blipped the throttle up to around 5K for just a second. As soon as I let off the gas and brought the RPMS back to around 2.5k the CEL light came on. I personally think that the Split second box is crap and it is responding a "split second to late" if you know what I mean. It could be that the RPMS are climbing so fast that the SS Box doesn't or can't respond in time to regulate the fuel OR that the RPMs are climbing so fast that the stock ignition setup isn't able to throw the spark quick enough. What do you think?

 

APS guys have this problem and they dont use the SS box.

 

If it isn't the SS Box maybe my OR statement might have something to do with it. What ignition upgrades are available for the G and Z?

 

That's funny I have my aps tt for 18k and got the code once when I need plugs.

 

mine goes and comes...

 

I believe that is basicly bull [ no offence ] I never had a P300 code with the SS box untill I change the fuel system . Look a couple posts up at that list of causes for the P300 code . The SS box is basic and does the job , just like all the other pibbybacks that alter signals to the engine .Like Sentry said , going FI changes just about every thing on the list of causes for the P300 code . Dont try to blame it on the SS box

 

+1

 

I spoke to my friend that works on Turbo cars all day and he believes it is my car running out of spark up high. I never had this problem with Stage 3 so he told me to pull my plugs and re-gap them a little lower to ~32 (I believe the stock gap is 41-44?). I am going to change my oil just in case I got some H2O in there from my water/meth kit and re-gap my plugs tomorrow night to see if that fixes the problem.

Thanks everyone for your comments. My350Z and G35Driver have been soooo much help.

 

Yeah I never thought about it until now. I did not have that problem with stage 2 or 3. If my work tomorrow does not fix the problem I will look into getting a replacement box. I think if I am going to keep my SC I am going to switch to the Unichip. That way I can get headers and a smaller pulley (to get my boost back up to ~7.5psi) and be able to tune it.

 

tim why dont you try the hks twin power dlI II ignition box,its gotten good reviews.it will give you quite a bit more spark energy and you can gap your plugs a little wider.

 

WTH are you to regulate what I write? Did you even read my whole statement above? Obviously not. I did have an OR statement in there. No offense.

Also, I did have it as a question also, not so that you can lay me out because I am throwing ideas and possibilities out there.

I am going to keep my opinion that the SS box is a load of ****. I haven't even had my SC and I am already on my second SS box. So whatever man.