This is the third time ive got this code in the past couple days, twice on Sunday at a autocross and this afternoon. the conditions were the same both times, i had been stopped for a little while, car in drive, a/c off. car seems to be running just fine. im going to log and try and get it to do it again tomorrow.

any ideas on what this could be. set up in sig.

 

http://www.obd-codes.com/trouble_cod...e-detected.php


if you do you own tuning...via ls1 edit, tuners, elive..etc

you can just disable the code assuming everything else is in order.

 

it does seem to have a little trouble idleing.

id rather not disable a code, it just doesnt seem like a good idea

i logged it yesterday and from idle to about 3000rpm the code is there, above that its gone. what do you all think???

 

if you've had your combo together awhile and never had this problem, i'd check the misfire monitor and see which cyl is contributing, and possibly start pulling plugs. If you didn't have a rough idle and now you do, I'd do this and go from there...

 

Does the car have a aftermarket camshaft in it? If so, thats the reason.

 

nope, completly stock internals, pretty much bolt ons, stall and a procharger

 

i have that same dang P0300 code. i get it if the car idles for a little bit. i never had a problem before i put the TR224 cam in my car. however, i changed so much at the time i have no idea what it could be. i also put on TSP 5.3L heads, LS6 intake, LS6 injectors, motor mounts, gmmg, etc. why would a cam cause this? anyway to prevent it? i am not seeing a noticable miss anywhere and the car runs strong.

 

ttt

on the hptuner log, the spark is a zig zag line, not straight

 

plugs check out ok,
changed both front o2's

any ideas? maybe if i changed the title to sts vs d1sc id get more responses

 

coils?

 

Has this been tuned since the converter?

 

Have you done the most important tuning change after a cam & stall? Meaning change ALL of the misfire tables to 32747 (or whatever that number is). Without doing that first, you are wasting your time IMO. Then you can work on optimizing the tune.

 

nothing has changed since its been tuned last, im still on the stock cam. the convertor has been in there a while, last change was the procharger and it was tuned a little while ago. it is deffiently misfiring, the spark graph on hptuners is erratic, like a zig zag line.

 

Its common to get misfire codes with aftermarket cam.I get the code 300 and was going to simply turn it off but am changing out engine and cam in spring so see what that cam does.
Like you said though you are on stock cam so should not get codes.You should look at individual cylinders with scanner and see if one is really high. Plugs and 02s can cause problems but you said you changed them? That would leave possibly wires or coil pack problem.

 

OK, so anything that makes the engine surge can result in misfire codes. And in the case of cams, or converters, or blowers, it's usually all fake. So bury the damn tables & see if it goes away. It could very well be something real, but I'd start there to make sure. That code will put the PCM into limp mode & you will be fighting with what you think you should see compared to what you are seeing.

 

im planning on swapping coils with a buddy on saturday to see if that fixes it.
im playing with hptuners to see if i can scan individual cylinders, if theres a way you can, let me know.

how do you bury the tables? im still new at hptuners.



thanks to all those helping out, i really appreciate it.

 

Not saying this will fix your problem, but it needs to be done with your mods.

Go into your file, select Eng Diagnostic, select Misfire, and type 32767 into very cell in all the tables, save it & load it up. Reset your code & start the car & see if it runs better. Now if it still misfires, you know you have a problem.

Often if it's a plug wires(s), the SES light will blink when it's running. Borrowing a coil pack would be a good way to isolate it. Might check the wire harness to the cam position sensor too. Hard to get at but sometimes they get pinched when reinstalling parts.

 

The SES flashes if the PCM picks up a misfire. The flashing is to represent higher priority than a constant light. GM does this so that you'll get the car serviced quicker hopefully because a misfire will quickly destroy the cats.. I guess they didn't want to have to warranty cats. (80K 8 year) because of a bad plug or something. Before I started swapping parts I would look at misfire data so you can zero in on the offending cylinder(s). Even a generic scan tool will do that.

 

just got done trying the misfire test wahusker suggested and same results, its misfiring.

attached is a short log of the test, i would really appreciate someone looking at it in hopes they might see something that i have missed

 

I'm thinkin you should take this to the tuning forum. But let me ask, what is your timing set at for idling? And your rpm? I assume at the end where the rpms drop & the timing falls off is where you are having this problem? Not showing any KR, so that isn't the problem......the inj's stay pretty constant....but it starts taking in more air & the short terms look like it's pulling fuel. Hmmmmm, could be a coil pack flaking out. Although the status bits say the coils are reporting good.....can't say I've checked them reading a log tho. Tis interesting for sure. (sorry, no help I know)