So I have had Detroit Rocker cams in the car for awhile now and every now and then I would get this code thrown (Random Misfire). Maybe once every few months so it wasnt a cause of concern. I then added a saleen supercharger and I hadnt thrown a code for about 6 months. I now have thrown the random misfire code 3 days in a row. Im thinking it could be a bad coil pack or one of the plugs are bad. What do u guys think. The car only has about 31k on it but with the cams im sure plugs and that get bad a bit quicker. The code is always thrown when I start the car and idle for about 5 minutes.

thanks

 

The cause is typically a vacuum leak in the intake manifold, throttle body or vacuum plumbing, a defective Exhaust Gas Recirculation (EGR) valve that is leaking exhaust into the intake manifold, or even bad gasoline. Less common causes include bad spark plug wires, worn or fouled spark plugs, a weak ignition coil, dirty fuel injectors, low fuel pressure, or weak valve springs. If a misfire is occurring in only one or two cylinders, you will usually find a misfire code for that specific cylinder rather than a random misfire code.

Hope this helps.

 

yea its not stating a specific cylinder but just random. Whats the best way to check for vacum leaks

 

Are you running their Brisk racing one step colder plugs and what is the gap(0.032 I am assuming). Not sure how to check for leaks in the vacuum but if you had a vacuum leak in those areas mentioned, you would most likely feel some sort of hesitation or gradual loss of power at WOT I believe.

If you mention that it's at idle, I would check the spark plug boots, and or the spark plugs themselves.

I forget where I have read it, but I hear the automatic cars have more issues with CAMS than the manual cars for some reason. Wish I was more help.. I forget the details on the subject...

 

It does no bucking at all and no hesitation. Been awhile since Ive had it wideopen but I will try that tomorrow and see what hapens. It really seems to run fine. The plugs are stock and they said I didnt need to change anything as far as plugs are concerned. Now when I get the stage 3 then i know they need to be gapped. And I know that there have some minor problems with auto's and cams but Ill try and tighten up a few things and see what happens

 

hmm.. I don't know... without having an IDS connected to it, it's kinda a shot in the dark (for me at least lulz)

I wouldn't rule out something simple like the spark plug boots or plugs themselves though. I might even go as far as pulling a few to see how they are.

I did that to mine when I suspected a misfire at idle. Turned out to be a dirty *** throttle body. I ended up opening the gap from 0.032 to 0.035, it idles better since then..

 

I will try cleaning that and see. I'll let you know what happens. I waxed the car and thought about taking it to the park for some pics so I will get her wideopen and see what happens

 

uh.. I'd wait to see if there is any hesitation/trouble before you go on those WOT runs.. If there is an issue with the spark plugs or a misfire, I'd be wary of speeding at all.

If you say it runs and drives fine though, it could very well be only at idle and more to do with the CAMs and the tune..

 

I'll do some cleaning and some tightening and go from there tomorrow. I'll see how she acts when I do all that but yea there has been no hesitation or bucking so we will see. And it could be the tune but hard to believe when it was fine for 8 months and then boom. I may have the dealership do a check on the coils and plugs.

 

What's your voltage during those times when codes are thrown?
Could have an alternator issue.

Plug gap or plugs could still be a problem.

BTW, we have no EGR in the 4.6L's.