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-   -   code po300 help (https://www.saturnforum.com/forum/general-tech-help-13/code-po300-help-9514/)

john doe 06-13-2014 05:02 AM

raining this morning and once again the misfire (or misfires) is back . so the icu replacement did not help .
nothing like throwing money away .

getting frustrated with this car .

john doe 06-13-2014 10:30 AM

just checked the codes again . now its a cyl 2 misfire again . out of sheer curiosity and frustration i swapped the coils from left to right just to see if the problem follows the coil .
now its running good again .so again only time will tell .its drying up out there too so that itself could be a factor .

with all this surrounding cyl 2 i am beginning to wonder if it could be a injector?

uncljohn 06-14-2014 07:27 AM


Originally Posted by john doe (Post 44031)
with all this surrounding cyl 2 i am beginning to wonder if it could be a injector?

Well? Why not, I guess.
I recently went through something similar on one of the cars I have. It is one that has a 1975 engine in it and in 2001 I converted it to a full fuel injection system. The engine management package was a factory direct conversion representing a 1994 Jeep engine control and while the results were mixed initially it id turn out to be a mechanically sound move. And it ran quite well up to about a year ago when it started to have what turned out to be a lean mixture back fire;
And it drove me nuts. I was able to obtain what is a very extremely heavy duty scan tool, a Snap On unit that was current for the years of the cars I am interested in using one on, the OBD-1 Logic for this car and the Pre-OBD-1 variation that my 94 Saturn has and the only error code this thing was able to pull was a map sensor overpressure code which was the direct result of the back fire, not the cause of it.
Being Frustrated to the nth degree it finally dawned on me to use some fuel injection cleaner to see if something was dirty. A product that in general I do not think is overly beneficial. But the first application lessened the incidence of backfiring. The second application eliminated it.
It ain't going to hurt to try I guess and see what happens. Use a good one though. The STP line of heavy duty injection cleaner has worked for me. And I am sure there are others.
Give at least one tank of gas using the stuff and see what happens. I went through two bottles of the stuff and I am glad I did.

john doe 06-14-2014 02:50 PM

i did try a bottle of fuel injection cleaner and it ran good for about 2 weeks afterwards .maybe time to try again .

uncljohn 06-15-2014 08:09 AM


Originally Posted by john doe (Post 44047)
i did try a bottle of fuel injection cleaner and it ran good for about 2 weeks afterwards .maybe time to try again .

That is a positive reaction. Then try it again. And purchase one of the better brands and get two bottles of them. There is some raspy fuel being manufactured now and as I have been in the hobby for longer then the age of my oldest children I have not seen a problem until the last 4 or 5 years and it will plug injectors among other things.
I do not drive my Saturn as often as I should and it suffers from sitting now. It is some that needs to be learned when it comes to maintaining something like that. A car that represents a hobby rather than a need for transportation.
"Specially something that is as complex as my Saturn is in comparison to my other collector cars. I have gone through 2 bottles of a premium brand fuel injector cleaner now and my previously mentioned AMC car with a hotrodded I-6 engine ran like a Swiss watch for the first time in 2 years. No more lean back fires and will travel the freeway speeds out here plus something with the A/C going as if it was a new car rather than something that is 34 years old. (Except for it's collection of rattles) Like I say, having a scan tool for these cars is the first order of trouble shooting. It may not tell you what you want to here but it tells you what is going on.
You are hearing a miss-fire and the scan tool says there is a code for a miss-fire, not what is causing it.
So it is not lying to you. And it tells you what cylinder it is.
My outdated Snap On scan tool which represents the state of the art technology for the early use of OBD-1 is far superior to the aprx $300.00 Scan tools I could buy over the counter and would have if the manufacture had not stated categorically that it would not work on my Saturn, which was one of the two reasons I was looking for one. The other being my retrofitted AMC car. And it turned out that car represented newer technology than the Saturn was. I was lucky enough to run across the situation where a prfessional mechanic friend had not bothered to up dat (at a grand a year or so) his professional tool and bought a new one and stuffed this one in a drawer. So he gave it to me.
I love it! It works (after repairs) on my 94 Saturn with it's weird pre-OBD-1 logic level computer and my AMC conversion and thinks it is a 94 Jeep Cherokee.
And if it ever acts up I will buy an autoparts store Scan tool for my 2007 Chrysler I bought new. Even spending that kind of money one use of it will pay for the expense of purchasing it. It is a good tool to have in our shade tree mechanic's tool box. Another one is a fuel pressure gauge which I never needed for working on carbureted cars but is indispensable on things with fuel injection.
Good Luck.

john doe 11-13-2014 07:45 AM

still getting a cyl 2 misfire now and again . i recently bought a new idle air control valve and it idles good now .
threw 2 cyl 2 misfire codes this week .
things i have tried

new plugs(a/c delco)
new wires
new ignition control unit(the one under the coils)
swapped coils to see if it follows coil(it did not)
plug and unplug engine management computer(silver box behind battery)just to clean the connecters
clean and reinstall plug number 2

i read somewhere that this could also be caused by a bad intake manifold gasket ,this true??
i am no saturn expert by far .been a ford guy mostly so saturn quirks are new to me .


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