P0300 Random/Multiple Cylinder Misfire Detected
 

P0300-Random/Multiple Cylinder Misfire Detected. Anybody have any ideas for possible causes? I have been tuning the VE and PE in SD for about a month,re-enabeled the MAF and this code popped up. I have no ideas, mods are in the sig.

Crank re-learn, fouled plugs (rich) :confused:

Werd, i'll try a crank re-learn. Can this be done with Hp-Tuners, if so how? I was planning on pulling my plugs tommorrow. Thanks for the tips, anybody else?

i replaced my plugs and wires and stopped getting misifire codes completely.

I had this code before...I have a ram air hood and I noticed it popped up every great once in a while when it was raining or snowing. Can you look at your misfire counts on each individual cylinder, that would narrow it down a lot.

Dave

Do you have a new cam? I had to desensitize the knock sensors after I went to 918's and higher lift cam as it set the same code.

Being too rich at WOT (open loop) can cause it too.

I have done the re-learn. So far no codes yet. I'll keep you guys posted as to what happens in the next few days. I'm gonna go back and check the tune once it gets sunny again. James B.- could you clarify the difference between open and closed loop? Thanks a lot for all the ideas.

PE or power enrich which is where you are when you are at WOT is open loop. So when you floor it you are in open loop.

Exactly. If it was rich at Wide Open throttle it would not be obvious because you get no LTrim or Strim when the PCM is in open loop. Open loop is where the PCM uses only VE to calculate fuel delivery instead of oxygen sensor feedback. (The PCM is in open loop when you first start up also while it waits for the O2 sensors to come up to temp.)