Hope someone can help me out here. My car just registered a code P0300 which
my scan tool registered:
"Random Multiple Cylinder Misfire Detected"
The car had done this before about 2 months back then stopped doing it. What
it did was like stutter when I start the car.
Sometimes the problem would last a while then dissapear for a long time but
it happened again today. And this is after the car had already been driven
about 12 over miles so engine was still quite warm. Just went into Costco
bought a few items and about half an hour tried starting my car and in idle
mode it kinda stuttered or sputtered but the engine did not die out though
it sure seemed like it was going to.
Now before I take it to the mechanic I would like to know what you guys
think. The car is a 96' V6 3.8LT Automatic. Last tune up was done around
May of 2003 and I had the plugs and filters changed. Even had an Induction
Service done. Can it be time for another Tune Up or what else could be the
I just don't want to get burned by the mechanic.
Thank you for any response.
What it sounds like to me:
Is a hot soak problem, where excess fuel is in the intake manifold when you
are going to start it up. The fuel pressure regulator diafram being ruptured
or a leaking injector would be a good place to start looking.
It's an easy test also, put on a fuel pressure gauge, cycle on the key a few
times. With a 15 second rest between cycles, to pressurize the fuel system
to the maximum.
Any leakage of more than one or two pounds in an hour or two. You found the
This is a seat of the pants diagnosis: Do not rip off a technician's head
like this is a gospel diagnosis!
I've got a '98 Astro which has been throwing the same code. I was told by the
guy that scanned it that it would most likely be the coil or the ignition
module... my buddy, an actual automotive engineer in Detroit agreed. Well,
they were both wrong and my pursuit continues. At this point I'm thinking fuel
Clint ('89 IROC, '90 RS, '01 Bandit heh, heh, heh)
Second hit on Google after using
Code P0300 as search criterion. Google is your friend, even on engine
Posted by C. Conway on June 24, 03 at 06:06:03:
In Reply to: Re: 98 4.3 random engine misfire code p0300 posted by mike on
June 17, 03 at 14:09:31:
: : Noticed at highway speeds (65-70) when the engine temp gauge is between
150-200, when I let off the accelerator, the truck feels like it is
lurching. At first I thought it was something hanging up in the
transmission. Had it put on an anylizer and the P0300 code came up. I
searched the engine compartment and noticed that the ignition coil had
arcing discoloration by the laminated steel core. I replaced the ignition
coil and it significantly reduced the amount of lurching feeling when driven
under the same circumstances, but did not entirely eliminate it. I am going
to replace the distributor cap, plug wires and plugs this weekend. Anything
else I should check while I'm at it?
: It only take one bad plug wire to ruin the coil. It can also damage the
: Found the problem, #3 spark plug was cracked where the porcelin meets the
body of the plug. I got up real early (3am) Saturday morning and checked for
arcing under the hood. Replaced all the spark plugs and truck runs great
now. Thanks Mike!
well, it's definately the famous Misfire code.....but its either spark
related or FI related. that happened to me once w/ my 98 Sonoma 4.3. The
funny thing was, my code was due to clogged fuel injectors (seems that STP
FI cleaner crapped up my injectors). I put some Lucas FI treatment in, and
never had that problem again.
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