Engine Misfire Code P0300 and P0305
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From: Woodland Hills
Engine Misfire Code P0300 and P0305
Hello,
I have a 2004 with a 3.0 engine. Been having this problem for some time.
At idle only after some time the engine will misfire and check engine light will start flashing. I turn off the engine, restart, all is okay. No engine performance problems at speed, only when I come to a stop, and not all the time.
I just replaced all plugs, old plugs did not show any obvious problem, all equally worn. Plug wires look good as well.
Same problem came back, after about 5 minutes of driving stopped and let it idle, it misfired and check engine light back on.
At idle the tach does not bounce, but the engine does idle a bit rough.
I need to get a smog check, need to figure this out.
181,000 mile on original engine.
I have a 2004 with a 3.0 engine. Been having this problem for some time.
At idle only after some time the engine will misfire and check engine light will start flashing. I turn off the engine, restart, all is okay. No engine performance problems at speed, only when I come to a stop, and not all the time.
I just replaced all plugs, old plugs did not show any obvious problem, all equally worn. Plug wires look good as well.
Same problem came back, after about 5 minutes of driving stopped and let it idle, it misfired and check engine light back on.
At idle the tach does not bounce, but the engine does idle a bit rough.
I need to get a smog check, need to figure this out.
181,000 mile on original engine.
Welcome to the forum
2004 to 2006 Rangers with 3.0l engines had a TSB regarding recessed exhaust valve SEATS
Seems the seats or head were mismatched and seat would move causing lower compression and misfires
You need to do a compression test
TSB
2004 to 2006 Rangers with 3.0l engines had a TSB regarding recessed exhaust valve SEATS
Seems the seats or head were mismatched and seat would move causing lower compression and misfires
You need to do a compression test
TSB
TSB 05-26-3
FORD: 2004-2006 Ranger
ISSUE
Some 2004-2006 Rangers 3.0L-2V "Vulcan"vehicles may exhibit:
- Malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P0300-P0306 and P0316
- Rough running at various RPM
- Rough idle
- Misfire
ACTION
This may be due to an engine exhaust valve seat recession causing a loss of compression. Refer to the following Service Procedure to diagnose exhaust valve seat recession.
SERVICE PROCEDURE
1. Perform a power balance rest to clarify if a cylinder is misfiring. Identify and keep record of any cylinder that has a concern.
2. Perform a manual compression test with the spark plugs removed to locate any cylinder that may have low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.
3. If no low compression is found per shop manual instructions, proceed with normal misfire diagnostics per the Powertrain Controls/Emissions Diagnosis (PC/ED) Manual for the appropriate model year.
4. If low compression is found and it is a cylinder that had a misfire on power balance, perform a leakdown test to determine the source of leakage that may be causing the low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.
5. If low compression is found in a cylinder that did not have a misfire detected then proceed with normal base engine diagnostics per the Workshop Manual, Engine System, General Information, 303-00.6.
If the exhaust valve is identified as the source, replace both cylinder heads with the newly released service cylinder heads. Refer to the appropriate Workshop Manual, Section 301-01A.
FORD: 2004-2006 Ranger
ISSUE
Some 2004-2006 Rangers 3.0L-2V "Vulcan"vehicles may exhibit:
- Malfunction indicator lamp (MIL) on with diagnostic trouble codes (DTCs) P0300-P0306 and P0316
- Rough running at various RPM
- Rough idle
- Misfire
ACTION
This may be due to an engine exhaust valve seat recession causing a loss of compression. Refer to the following Service Procedure to diagnose exhaust valve seat recession.
SERVICE PROCEDURE
1. Perform a power balance rest to clarify if a cylinder is misfiring. Identify and keep record of any cylinder that has a concern.
2. Perform a manual compression test with the spark plugs removed to locate any cylinder that may have low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.
3. If no low compression is found per shop manual instructions, proceed with normal misfire diagnostics per the Powertrain Controls/Emissions Diagnosis (PC/ED) Manual for the appropriate model year.
4. If low compression is found and it is a cylinder that had a misfire on power balance, perform a leakdown test to determine the source of leakage that may be causing the low compression. Refer to the appropriate Workshop Manual, Engine System, General Information, 303-00.
5. If low compression is found in a cylinder that did not have a misfire detected then proceed with normal base engine diagnostics per the Workshop Manual, Engine System, General Information, 303-00.6.
If the exhaust valve is identified as the source, replace both cylinder heads with the newly released service cylinder heads. Refer to the appropriate Workshop Manual, Section 301-01A.
Best to take this issue off the table first, so you don't waste money on non-fixes if it is the problem
Compression is either good or it isn't, can't be an intermittent issue like spark and fuel
Make sure to remove ALL spark plugs first, you need fast crank shaft speed to get highest compression, the higher the compression the bigger the differences will be in a failing cylinder(s)
Then test one cylinder at a time
If you press gas pedal down to the floor first, then crank the engine the fuel injectors will be turned off, it is called "Clear Flooded Engine" mode
Throttle position sensor at WOT(wide open throttle) with engine at 0 RPMs shuts off injectors while cranking engine, all fuel injection computers have this, not a Ford thing
Compression is either good or it isn't, can't be an intermittent issue like spark and fuel
Make sure to remove ALL spark plugs first, you need fast crank shaft speed to get highest compression, the higher the compression the bigger the differences will be in a failing cylinder(s)
Then test one cylinder at a time
If you press gas pedal down to the floor first, then crank the engine the fuel injectors will be turned off, it is called "Clear Flooded Engine" mode
Throttle position sensor at WOT(wide open throttle) with engine at 0 RPMs shuts off injectors while cranking engine, all fuel injection computers have this, not a Ford thing
Last edited by RonD; May 29, 2017 at 11:08 AM.
Thread Starter
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Member
Joined: May 2017
Posts: 15
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From: Woodland Hills
Did the compression check. Dry test. On cylinder 5 and 6 pressure from gauge fell quickly down to 80. Cylinders 1-4 pressure went down, but very slow.
1-130
2-130
3-145
4-155
5-120
6-120
What next, maybe a cylinder leak down test?
1-130
2-130
3-145
4-155
5-120
6-120
What next, maybe a cylinder leak down test?
You could stick some air pressure into the low cylinders and listen at the tail pipe for escaping air, leaking exhaust valve
But the numbers pretty much tell you there is a problem
Wet test could confirm Rings are OK, if numbers don't come up much with oil added then Rings are OK, number will always go up a bit on wet test
Leaking valves aren't effected by adding oil
But the numbers pretty much tell you there is a problem
Wet test could confirm Rings are OK, if numbers don't come up much with oil added then Rings are OK, number will always go up a bit on wet test
Leaking valves aren't effected by adding oil
Thread Starter
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Joined: May 2017
Posts: 15
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From: Woodland Hills
I am still having the problem, only at an idle. I was able to pass the smog check, so I am going to drive it until it dies. I am very sure it is the valve seat issue that is mentioned in this thread.
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