I've been away from home a bit since the head/cam install in Aug (see sig) and now I'm trying to put some miles on her. I'm getting a DTC P300 if I the car idles for @ 5 min. If I clear the code and drive normally, stopping at lights etc... no code. I believe that I'm getting the code because of the aggressiveness of the cam - it's kind of hard to decifer the FSM, doesn't cover mods.
Has anyone else experienced this? Am I off-base with my assumption [ yea, I know A$$-U-ME) but I don't want to destroy the car before the dyno tune in Jan. Thoughts?

it doesn't cover mods, but it will tell us what a P300 means!!!

Quote:
Yeah, I am clue less to that as well

I can check, but that means going out to the garage, and it's kinda chilly, I am tired, and have a cold...

P300 Engine misfire detected, my apologies for the ambiguity in the post

yea, i read the comments from TJWong on your post over at CF (before the database crashed, that is). I agree, the OBDII does cause issues with cam changes.

I just hope you don't have to pass a CARB type test... Get that thing tuned!!!

Thanks, I'm trying. No tuners in the area for C4s/LT1s. Would prefer not to use mail order tune, but hopefully the dyno tune will happen by mid Jan.

you can buy a hyperchip type programmer for that, and I suspect TJ Wong would be willing to lend you a hand on getting the numbers right.

It doesn't have to be spot on, just within a good range.

[size=13:ef0e518ae9][font=Times New Roman:ef0e518ae9]Below are quotes from another forum that answered my original question concerning the cause of my DTC P300:

[color=darkred]"On a '96, you'll need to have the parameters for the misfire rpm changed (or the idle raised to ~850rpm) to avoid setting a misfire code (P0300). I bumped the misfire tables in mine such that the min rpm it looks for misfire is 1500 rpm. Btw, '96 is the *only* C4 that has this issue because it's the *only* C4 that has OBDII. Another poster mentioned "misfire code" in conjunction with his '95. '95s do not have the capability to set this code (not OBD II, no crankshaft position sensor, etc)."[/color:ef0e518ae9]

Why would it register a misfire? Is that caused by the idle loping or spitback at low rpms?

"[color=darkred]Technically either could cause it....a cam with a lope or a poorly running engine. To detect misfire, the PCM looks at the acceleration and deceleration of the crankshaft via the crankshaft position sensor. Every time a cylinder fires, the crank accelerates and between cylinder firing, there's a small deceleration of the crank. When the boundries programmed into the software are exceeded, the PCM cries misfire.

By raising the rpm, you get away from the "lope". Conversely, if you like the lope then change the misfire detection rpm so the PCM doesn't look at the info until the engine is at a higher rpm."[/color:ef0e518ae9][/font:ef0e518ae9][/size:ef0e518ae9]

you may need to replace your alternator :thumbright: