[Diy_efi] P0300 Random/Multiple Cylinder Missfire Detected

[Perry Harrington]

Or it could just be standard GM goodness.

We've got a 98 astro 4.3 that misfires all the time.  I just plugged
the scanner into it today and read out a miss on cyl 3.  I started
it up and the miss is gone.

The other day it wouldn't make it out of the parking lot.

Heh, my 94 pickup started randomly missing and wouldn't run.  I
replaced the plugs (the wires and cap have about 8k miles on them)
and it didn't help.  Rebuilt the fuel pressure regulator and it
seemed to help a bit.  Pulled out the idle motor and checked for
deposits, clean.  Then I replaced the coolant temp sensor and it
started running fine.  The damn sensor was reading 32Meg when in
the engine and normal when out.  The sensor was causing it to
run pig rich.  I even disconnected ONE of the injectors and it
ran almost normal.  The computer should have detected the fault
and limped, but it just screwed up.  Good thing I had a sensor lying
around...

I can't say that I'm impressed by the GM goodness.

--Perry

On Wed, Jun 26, 2002 at 09:18:10PM -0400, Mazda Ebrahimi wrote:
> Have you tried adjusting or at least checking your plug gaps?
> Might be worth a shot reducing the gap...
> 
> -----Original Message-----
> From: diy_efi-admin at diy-efi.org [mailto:diy_efi-admin at diy-efi.org] On
> Behalf Of Matthew McCain
> Sent: Wednesday, June 26, 2002 8:17 PM
> To: diy_efi at diy-efi.org
> Subject: [Diy_efi] P0300 Random/Multiple Cylinder Missfire Detected
> 
> Hello,
>         I have a 2001 Chevy Blazer that has 30K miles on it.  I can feel
> it
> missing slightly when going up hills. Only when the TCC is engaged, I
> know
> you will feel more of a miss then.  When I go up steep hills on the
> interstate the MIL will start to flash indicating a missfire is going
> on.
> Then sometimes it will stay on constantly.  It is under warenty with GM,
> They can not find a problem with it other than a P0300 code.  They gave
> the
> ECM a firmware update, and it seemed to help for a while.  I have read
> on
> the net that for some reason the wires on a blazer need to be changed
> every
> 30K miles to eliminate the problem.  I have inspected the wires and they
> look good.  I know sometimes you can't tell by looking at them.  It
> idles
> ok, and accelerates ok.  Any suggestions?  Thoughts?
> 
> Thanks,
> Matt
> 
> 
> 
> 
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-- 
Perry Harrington			Data Acquisition & Instrumentation, Inc	
perry at dainst dot com					 http://www.dainst.com/		 

Those who would give up essential liberty to purchase a little temporary safety
deserve neither liberty or safety. Nor, are they likely to end up with either.
                             -- Benjamin Franklin

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