Cylinder 3 & 4 Misfire on Cold Start
#1
10-29-2023, 02:08 AM
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Cylinder 3 & 4 Misfire on Cold Start
Howdy
I’ve got a 2004 Disco 2 with a little over 100k miles. I’ve had several problems with overheating in the past and have had the head gasket replaced twice. I’ve taken her off road often in the past and have had problems with mud in the radiator and other components - I’ve since tried to stay out of deep sludge for the most part.
Over the last month or so I’ve been driving myself crazy trying to diagnose misfires on cylinders 3 and 4 on cold start. Sometimes I’ll go a day without issues but they continually resurface. Service engine light starts blinking on cold start and then goes solid. Truck drives well after.
So far I’ve replaced the plugs, wires, and coils. Thought I’d solved the problems but the misfires have persisted. My next thoughts are to replace the injectors and the crankshaft sensors as I’ve heard those are common culprits. Any advice on these jobs would be appreciated.
Two months back I blew a radiator hose on the freeway and nearly overheated (only noticed from engine temp gauge). My fear is a problem with the head gasket or a potential piston but I’d imagine the truck would run poorly under such circumstances. No coolant loss or white smoke/coolant in the exhaust. Steady temperatures throughout.
I’m also pulling random misfire codes and a few manufacturer control codes, namely the p1300. Any thoughts appreciated.
Cheers.
I’ve got a 2004 Disco 2 with a little over 100k miles. I’ve had several problems with overheating in the past and have had the head gasket replaced twice. I’ve taken her off road often in the past and have had problems with mud in the radiator and other components - I’ve since tried to stay out of deep sludge for the most part.
Over the last month or so I’ve been driving myself crazy trying to diagnose misfires on cylinders 3 and 4 on cold start. Sometimes I’ll go a day without issues but they continually resurface. Service engine light starts blinking on cold start and then goes solid. Truck drives well after.
So far I’ve replaced the plugs, wires, and coils. Thought I’d solved the problems but the misfires have persisted. My next thoughts are to replace the injectors and the crankshaft sensors as I’ve heard those are common culprits. Any advice on these jobs would be appreciated.
Two months back I blew a radiator hose on the freeway and nearly overheated (only noticed from engine temp gauge). My fear is a problem with the head gasket or a potential piston but I’d imagine the truck would run poorly under such circumstances. No coolant loss or white smoke/coolant in the exhaust. Steady temperatures throughout.
I’m also pulling random misfire codes and a few manufacturer control codes, namely the p1300. Any thoughts appreciated.
Cheers.
#2
10-29-2023, 09:30 AM
Mudding
Join Date: Jul 2021
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Have you done a compression test? Once compression drops below a certain psi it will trigger a missfire. In my experience it will do a random missfire cel along with the guilty cylinder cel.
The compression readings increase as the engine warms.
I'd try checking compression.
I compressor looks good do a smoke test next to check for vacuum leaks.
At that point I'd start looking for bad plug wire connection and swapping parts between cylinders (wires and or injectors) to see if the offending part can be found in it's new location.
The compression readings increase as the engine warms.
I'd try checking compression.
I compressor looks good do a smoke test next to check for vacuum leaks.
At that point I'd start looking for bad plug wire connection and swapping parts between cylinders (wires and or injectors) to see if the offending part can be found in it's new location.
#3
10-29-2023, 07:48 PM
Camel Trophy
Have you done a compression test? Once compression drops below a certain psi it will trigger a missfire. In my experience it will do a random missfire cel along with the guilty cylinder cel.
The compression readings increase as the engine warms.
I'd try checking compression.
I compressor looks good do a smoke test next to check for vacuum leaks.
At that point I'd start looking for bad plug wire connection and swapping parts between cylinders (wires and or injectors) to see if the offending part can be found in it's new location.
The compression readings increase as the engine warms.
I'd try checking compression.
I compressor looks good do a smoke test next to check for vacuum leaks.
At that point I'd start looking for bad plug wire connection and swapping parts between cylinders (wires and or injectors) to see if the offending part can be found in it's new location.
#4
11-15-2023, 02:57 PM
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Update
Have you done a compression test? Once compression drops below a certain psi it will trigger a missfire. In my experience it will do a random missfire cel along with the guilty cylinder cel.
The compression readings increase as the engine warms.
I'd try checking compression.
I compressor looks good do a smoke test next to check for vacuum leaks.
At that point I'd start looking for bad plug wire connection and swapping parts between cylinders (wires and or injectors) to see if the offending part can be found in it's new location.
The compression readings increase as the engine warms.
I'd try checking compression.
I compressor looks good do a smoke test next to check for vacuum leaks.
At that point I'd start looking for bad plug wire connection and swapping parts between cylinders (wires and or injectors) to see if the offending part can be found in it's new location.
Ive since had the compression checked and values aren’t perfect but within the acceptable range. A local shop directed me towards a faulty ECU. They said their lab scope was tracking no voltage to the injectors on startup. That component has been replaced but the misfires persist.
As mentioned earlier the coils, wires, and plugs have all been replaced. The injectors have been swapped and the misfires did not follow the injectors.
#6
11-19-2023, 03:05 PM
Camel Trophy
Appreciate the advice.
Ive since had the compression checked and values aren’t perfect but within the acceptable range. A local shop directed me towards a faulty ECU. They said their lab scope was tracking no voltage to the injectors on startup. That component has been replaced but the misfires persist.
As mentioned earlier the coils, wires, and plugs have all been replaced. The injectors have been swapped and the misfires did not follow the injectors.
Ive since had the compression checked and values aren’t perfect but within the acceptable range. A local shop directed me towards a faulty ECU. They said their lab scope was tracking no voltage to the injectors on startup. That component has been replaced but the misfires persist.
As mentioned earlier the coils, wires, and plugs have all been replaced. The injectors have been swapped and the misfires did not follow the injectors.
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