Misfire Cylinder #3
Headnsouth
04-04-2007, 08:16 PM
I need some help on diagnosing this 98 with 170k miles on her. The plugs look great white/light grey in color. Wires were changed within the year so I'm leaning toward an intermittent bad coil pack. Cylinder #1's coil pack was replaced within the year ago. Suggestions, comment, ideas?
Did a comp. check:
I really didn't see the need to squirt oil into the back 3 after I did the front 3. If it was easy I would have done it but if you've ever worked on this engine I'm surprised I even got a compression check done in less than 30 minutes.:iceslolan
I was thinking of the worst case with these kind of miles considering the history of head gasket jobs on this engine. But I feel pretty good with all but cylinder #2 (which still isn't too bad considering the mileage).
Anybody know what the new engine comp # should be?
Comp check info.
Cylinder before/after oil
1-160 3-160 5-165
2-100/135 4-160/165 6-160/170
here's some info from my AutoTap
AutoTap Diagnostic - Version 3.00
Check Engine Light: ON
Time Since Codes Cleared: ---
Distance Since Codes Cleared: ---
Drive Cycles Since Codes Cleared: ---
Confirmed Diagnostic Trouble Codes:
Code: Description:
P0172 Fuel Trim System Rich Bank 1
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0303 Cylinder 3 Misfire Detected
Possible Diagnostic Trouble Codes:
Code: Description:
P0172 Fuel Trim System Rich Bank 1
P0303 Cylinder 3 Misfire Detected
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
--------: EMISSION TEST STATUS :--------
Emission Status: <SELECT DATE>
Vehicle Model Year: <SELECT>
OBD Compliant: Yes
Misfire Monitoring: Complete
Heated Catalyst Monitoring: Not Supported
Comprehensive Component Monitoring: Complete
Catalyst Monitoring: Complete
Fuel System Monitoring: Complete
Evaporative System Monitoring: Complete
Secondary Air System Monitoring: Not Supported
EGR System Monitoring: Complete
Oxygen Sensor Monitoring: Complete
Oxygen Sensor Heater Monitoring: Complete
A/C System Refrigerant Monitoring: Not Supported
--------: FREEZE FRAME DATA :--------
Generated by DTC code: P0303
Fuel System Status Bank 1: CL-1
Calculated Engine Load: 37.3 %
Engine Coolant Temperature: 106 °F
Short Term Fuel Trim Bank 1: -2.3 %
Long Term Fuel Trim Bank 1: -0.8 %
Manifold Absolute Pressure (MAP): 27.8 in Hg
Engine Speed: 2317 RPM
Vehicle Speed: 16 MPH
Mass Air Flow Rate: 7.372 lb/min
Throttle Position Angle: 46.3 %
Did a comp. check:
I really didn't see the need to squirt oil into the back 3 after I did the front 3. If it was easy I would have done it but if you've ever worked on this engine I'm surprised I even got a compression check done in less than 30 minutes.:iceslolan
I was thinking of the worst case with these kind of miles considering the history of head gasket jobs on this engine. But I feel pretty good with all but cylinder #2 (which still isn't too bad considering the mileage).
Anybody know what the new engine comp # should be?
Comp check info.
Cylinder before/after oil
1-160 3-160 5-165
2-100/135 4-160/165 6-160/170
here's some info from my AutoTap
AutoTap Diagnostic - Version 3.00
Check Engine Light: ON
Time Since Codes Cleared: ---
Distance Since Codes Cleared: ---
Drive Cycles Since Codes Cleared: ---
Confirmed Diagnostic Trouble Codes:
Code: Description:
P0172 Fuel Trim System Rich Bank 1
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0303 Cylinder 3 Misfire Detected
Possible Diagnostic Trouble Codes:
Code: Description:
P0172 Fuel Trim System Rich Bank 1
P0303 Cylinder 3 Misfire Detected
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
--------: EMISSION TEST STATUS :--------
Emission Status: <SELECT DATE>
Vehicle Model Year: <SELECT>
OBD Compliant: Yes
Misfire Monitoring: Complete
Heated Catalyst Monitoring: Not Supported
Comprehensive Component Monitoring: Complete
Catalyst Monitoring: Complete
Fuel System Monitoring: Complete
Evaporative System Monitoring: Complete
Secondary Air System Monitoring: Not Supported
EGR System Monitoring: Complete
Oxygen Sensor Monitoring: Complete
Oxygen Sensor Heater Monitoring: Complete
A/C System Refrigerant Monitoring: Not Supported
--------: FREEZE FRAME DATA :--------
Generated by DTC code: P0303
Fuel System Status Bank 1: CL-1
Calculated Engine Load: 37.3 %
Engine Coolant Temperature: 106 °F
Short Term Fuel Trim Bank 1: -2.3 %
Long Term Fuel Trim Bank 1: -0.8 %
Manifold Absolute Pressure (MAP): 27.8 in Hg
Engine Speed: 2317 RPM
Vehicle Speed: 16 MPH
Mass Air Flow Rate: 7.372 lb/min
Throttle Position Angle: 46.3 %
LMP
04-06-2007, 02:25 PM
Well..I traced back your previous posts ...there is an history of misfires...but nothing more alarming. What leads you into that investigation? ANy other operational symptoms?
160-170 is absolutely good, and of course 100-120 is a little low on #2: gasket leak? valve? rings?...if that is all there is, and no other symptoms, I'd be tempted to let go..and wait. If you loose coolant and other symptoms develop, then I'd be afraid of gasket failure...my brother just blew one this morning (Montana 2002), one more on the open list of fatalities.
160-170 is absolutely good, and of course 100-120 is a little low on #2: gasket leak? valve? rings?...if that is all there is, and no other symptoms, I'd be tempted to let go..and wait. If you loose coolant and other symptoms develop, then I'd be afraid of gasket failure...my brother just blew one this morning (Montana 2002), one more on the open list of fatalities.
Headnsouth
04-11-2007, 07:12 AM
No other problems besides the misfire. I put it all back together and went to start it up but the fuel rail seal was leaking so as soon as I get a chance to replace it I'll fire it up and see if the replacement of the coil pack did it. That the only thing I could think of besides a plug wire. We'll see.
I'm hoping I can replace the seal without tearing half the stuff out again.
I'm hoping I can replace the seal without tearing half the stuff out again.
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