Problem with my 1997 Chevy Monte Carlo LS
3.1L V6 engine
Check engine lights flash
OBDII codes = p0300
work done prior = change all sparks plugs and wires
tech = all
question = Why does my check engine light have this code p0300. We
replaced coils and spark plug wire.
JK:
First you need to find out which cylinder(s) is misfiring.
If plugs and wires were replaced, another common cause for misfiring is a
burned / corroded ignition coil. That should have been obvious while
replacing the plug wires.
Another common cause for p0300 on this engine is a sticking injector or
rocker arm problem. Click here for more info.
3.1L V6 engine
Check engine lights flash
OBDII codes = p0300
work done prior = change all sparks plugs and wires
tech = all
question = Why does my check engine light have this code p0300. We
replaced coils and spark plug wire.
JK:
First you need to find out which cylinder(s) is misfiring.
If plugs and wires were replaced, another common cause for misfiring is a
burned / corroded ignition coil. That should have been obvious while
replacing the plug wires.
Another common cause for p0300 on this engine is a sticking injector or
rocker arm problem. Click here for more info.
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Chevy Monte Carlo SES
Problem with my 1995 Monte Carlo Z34.
3.4 DOHC
dash lights = no
Work done to repair this problem = Replaced Idle Air Control Valve.
Question = My 3.4 idles VERY rough and dies cold. When warm the idle is somewhat erratic and
although a little high it is tolerable. I cannot find any vacuum leak which is what I suspect. I
replaced the idle air control valve and am now suspecting the EGR (it is digital). I'm not sure if it
can be cleaned or not...... Any suggestions?
3.4 DOHC
dash lights = no
Work done to repair this problem = Replaced Idle Air Control Valve.
Question = My 3.4 idles VERY rough and dies cold. When warm the idle is somewhat erratic and
although a little high it is tolerable. I cannot find any vacuum leak which is what I suspect. I
replaced the idle air control valve and am now suspecting the EGR (it is digital). I'm not sure if it
can be cleaned or not...... Any suggestions?
GM Tech JK:
This IS a classic sign of a vacuum leak on the Dual Overhead Cam Motor (DOHC).
Especially the lower intake manifold gaskets as they meet the head, the PCV valve pipe
on the drivers side rear of the rear cylinder head, or the brake booster vacuum hose.
Concentrate spraying carb cleaner on these areas when warmed up to see if the idle will
change. Be sure to stay away from any ignition source, as the spray is VERY flammable.
This IS a classic sign of a vacuum leak on the Dual Overhead Cam Motor (DOHC).
Especially the lower intake manifold gaskets as they meet the head, the PCV valve pipe
on the drivers side rear of the rear cylinder head, or the brake booster vacuum hose.
Concentrate spraying carb cleaner on these areas when warmed up to see if the idle will
change. Be sure to stay away from any ignition source, as the spray is VERY flammable.
