I installed a Comp Cam with a 112 LSA. The Duration is only 206/212, but the lift is a little steep at 565/572. I got P0300 DTC after the cam install which is RANDOM MISFIRES. I cleard the code soon after I put the cam in, but it came back a few days later. I figured the first time the MIL came "ON" was an abberation because the SES lite stayed "OFF" for quite a while until it recently came back "ON". I'm guessing the 112 LSA has more to do with the P0300 DTC than either the Duration or Lift. Is there an easy fix for this random misfire problem the the PCM is "SEEING" due to the new camshaft?

 

Welcolm to to club! If my car does a lot of idleing with out some steady cruising in between I will occasionally get this code, although I haven't done it a lot of people have had this desencatised(spelling?) by edit.

 

I had the same problem for a week. I just solved it today. Does ur car pop? I mean do u hear the missfire from the exhaust? Did u change the spark plugs when u changed the cam? If u did what did u gap the spark plugs at?

My problem was that i gapped the spark plugs at .035 and i got alot of missfire and the same code. Today i changed the plugs and gapped them at .052 and the car is running perfect with no missfire. I hope this helps.

 

99% of folks will get a PO300 after a cam install. Completely normal. It needs to be tuned out with edit.

 

That is the truth about the 112 rather than the dur. That is the smallest dur however that I have ever heard of throwing a p0300 even though on 1 112. But if it is on a 112 it should be expected.

Jeremy Formato

 

Its expected and using ls1edit you can make the misfire detection just a little less picky by changing ( at least I did ) all the misfire values that are 32767 to 32000 and no more codes.

 

yup, just change all the values or turn the code off. Large cams will need the mid range misfire values changed to in auto cars or you will have lockup problems.

Jordan

 

Just to add to this. I have changed all the tables at idle, low rpm per cyl, etc.. to 32000 from 32767. I still get the P0300 random missfire. Usually happens when I let the car idle for a long time. Car runs fine at least I think it does. Should I just turn of the P0300 random missfire code? I hate to do that, but in order for this dang SES light to go off I might have to do that.
I know if there is ever a missfire there are codes that are set per cylinder. P0301, P0302, etc...
Any input?

 

You could try and adjust the mid engine speed tables also. I had to do this on my car to get rid of all the problems.

Hope this helps
Jordan