Reoccuring P0300
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Joined: Oct 2009
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Reoccuring P0300
This code states Random Multiple Misfires Detected. I have looked around on the forums and have seen the common problem to be the distributor. I have recently changed the following items. Distributor, cap, rotor, plugs, & wires. Everything is brand new and seemed to fix the majority of the problem I was having with it. A couple days after I replaced all of this the trouble code came back. Usually it is throw when just driving normal down the road. If I clear it, will sometimes come back the next day or possible several days later. I have started to noticed it sputter very little randomly at idle. I am unsure as to why this is occurring and if it influences the code. I am just looking for some advise as to what could be causing this. I am thinking of possibly changing the fuel filter and running some injector cleaner threw the system to see if that may help. Another thing I should note which may or may not be a factor is that the exhaust has a leak in it. The previous owner cut a section of it out to make it easier to remove the trans and replaced it with the wrong size flex pipe. Any advise is greatly appreciated. Thanks
Starting Member
Joined: Mar 2010
Posts: 113
Are your spark plug wires routed properly?
Misrouted wires emit EMI - electromagnetic radiation - same as a nuke, which can cause problems with solid state electronics, and cause false DTC's UH huh.
Ask me how I know been there did that saw it in the vette manual one day after 10 weeks chasin' down a false code per spec diags AHA EUREKA YUP.
Misrouted wires emit EMI - electromagnetic radiation - same as a nuke, which can cause problems with solid state electronics, and cause false DTC's UH huh.
Ask me how I know been there did that saw it in the vette manual one day after 10 weeks chasin' down a false code per spec diags AHA EUREKA YUP.
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New Member
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I have not had the ICM or the coil tested. As for the routing of the wires, I am pretty curtain they are routed correctly. To explain the "sputter" more clearly, the RPMs will fluctuate no more than 100 RPMs at idle. This is the only time there is a problem. While in motion there doesn't seem to be a problem.
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Joined: Mar 2010
Posts: 113
Yo-yo idling loping idle is a vacuum leak yup.
This is the BEST AND ONLY PROPER leak detection method, perfected by yours truly YUP UH HUH BOOKMARK IT.
This is the BEST AND ONLY PROPER leak detection method, perfected by yours truly YUP UH HUH BOOKMARK IT.
Originally Posted by Schrade 
No one got the proper technique for vacuum leak detection...
FIRST (fully warmed up motor); block the pedal, or block the throttle linkage. YOU HAVE TO DO THIS TO GET A STEADY IDLE , around 1,250 rpms, or a little higher. If you don't, you can fish starting fluid, a propane hose, or WD40, or Krylon, or hair spray, or pee, anything, until you need a sweater in Hades, but if the motor is lopin' idle already from a vacuum leak, you ain't gonna' find any vacuum leak, unless it's so big that Little Jack Horner can stick his thumb in it and pull out a pineapple NOPE.
AFTER you get a steady idle, THEN, you can spray starting fluid everywhere - that's the best detector, because it's vapor pressure is very high - a LITTLE at a time, until you get the SURGE. Follow the vacuum lines to the EVAP cannister too. You might even have to follow the EVAP lines from the EVAP cannister to the gas tank too, but that vac leak will show up as a DTC 32 EGR fault, and won't normally show as loping idle, unless the EVAP cannister has been by-passed (been there, saw that uh-huh).
If you get a surge in a tight spot, and can't tell exactly where it is, light a book of matches, blow out the match heads while they're still burnin', and feed the smoke to the tight spot.
Fear not the starting fluid; you cannot put the can down fast enough and light the matches fast enough to catch the starting fluid, because the vapor pressure is so high.
Bookmark this post YUP.
Wrench Wizard OUT!
No one got the proper technique for vacuum leak detection...
FIRST (fully warmed up motor); block the pedal, or block the throttle linkage. YOU HAVE TO DO THIS TO GET A STEADY IDLE , around 1,250 rpms, or a little higher. If you don't, you can fish starting fluid, a propane hose, or WD40, or Krylon, or hair spray, or pee, anything, until you need a sweater in Hades, but if the motor is lopin' idle already from a vacuum leak, you ain't gonna' find any vacuum leak, unless it's so big that Little Jack Horner can stick his thumb in it and pull out a pineapple NOPE.
AFTER you get a steady idle, THEN, you can spray starting fluid everywhere - that's the best detector, because it's vapor pressure is very high - a LITTLE at a time, until you get the SURGE. Follow the vacuum lines to the EVAP cannister too. You might even have to follow the EVAP lines from the EVAP cannister to the gas tank too, but that vac leak will show up as a DTC 32 EGR fault, and won't normally show as loping idle, unless the EVAP cannister has been by-passed (been there, saw that uh-huh).
If you get a surge in a tight spot, and can't tell exactly where it is, light a book of matches, blow out the match heads while they're still burnin', and feed the smoke to the tight spot.
Fear not the starting fluid; you cannot put the can down fast enough and light the matches fast enough to catch the starting fluid, because the vapor pressure is so high.
Bookmark this post YUP.
Wrench Wizard OUT!
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New Member
Joined: Oct 2009
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Well I am missing my vacuum reservoir if that makes a difference. I know people have said it will cause all sorts of things to go haywire but I have not had anything mentioned happen. Not to mention that you can only find them at junk yards. The nipple broke off so i simply just did the old screw in the line trick.
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