Code P0300

Tiny
CGHAWKINS
  • MEMBER
  • 2001 MITSUBISHI MONTERO
  • 3.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 113,000 MILES
DTC p0300 random misfire.
Wednesday, May 23rd, 2018 AT 4:30 PM

6 Replies

Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
I would start with some new spark plugs and see if the misfire goes away.
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Wednesday, May 23rd, 2018 AT 5:58 PM
Tiny
CGHAWKINS
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  • 5 POSTS
The car was brought to me with code p0300. Had low voltage at alternator so I repaired that. I run across ignition problems frequently caused by low voltage. Thought that fixed it. Test drove and p0301 popped up. Swapped coils code repeated. Checked for spark through wire. It fires. Changed spark plug. No oil leak in spark plug hole. Test drove and p0300 pops up every test drive now. Information I have gathered tells me random misfire is caused by maligned readings from cam and crank sensors. Timing belt is okay, marks are lined up at both cam and crank sprockets.
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Wednesday, May 23rd, 2018 AT 7:35 PM
Tiny
CGHAWKINS
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  • 5 POSTS
Sorry after changing the plug code p0301 popped up once again with p0300. So I put the old plug back in. I have test drove three cycles since and only p0300 pops up.
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Wednesday, May 23rd, 2018 AT 7:46 PM
Tiny
PATENTED_REPAIR_PRO
  • MECHANIC
  • 1,853 POSTS
I would start with some new spark plugs and see if the misfire goes away.
If not, you might want to consider getting a look at the number of misfires on each cylinder to find out which are causing the P0300 using a scan tool with that function. Perhaps taking a test drive to an AutoZone or Advance auto and have them scan it for the counts.
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Thursday, May 24th, 2018 AT 7:23 AM
Tiny
CGHAWKINS
  • MEMBER
  • 5 POSTS
Well this thing runs fine at idle in or out of gear. Thanks for your input.
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Thursday, May 24th, 2018 AT 8:49 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,256 POSTS
You need to use OEM plugs anything else and the car will misfire also. I would try a different MAP because they can be off a little causing a lean mixture and misfire. Also, I have seen the strainer plug up on the fuel pump causing low fuel delivery. Here are diagrams so you can see what I am talking about.

Check out the diagrams (below). Please let us know what happens.

Cheers, Ken
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Thursday, May 24th, 2018 AT 5:01 PM

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