ERUSH97XLT
Well-Known Member
- Joined
- October 9, 2008
- Messages
- 236
- Reaction score
- 1
- City, State
- Omaha, NE
- Year, Model & Trim Level
- 01 XLT, 03 XLT, 13 XLT
Hello,
Cylinder #4 is misfiring again, so my nifty OBD-2 Laptop hookup says. No codes, active or pending. The subsequent rough idle is slightly annoying, but not nearly as bad a last time. Check out my previous thread for more info on my issues with cylinder #4:
http://www.explorerforum.com/forums/showthread.php?t=225969
Here's my process:
If this was a gross air/fuel/ignition issue, all cylinders would be misfiring or running a bit rough. Since my scanner tells me the misfires only occur on cylinder #4, this narrows down a lot (Vacuum leak, MAF, IAC, EGR, DPFE, etc.), right? Unless there is a slight vacuum leak right at #4's intake. . . what do you think?
1. Ignition:
I just replaced the sparkplug again with little results. I'm reluctant to replace the sparkplug wires again because they are so fresh (and a bit more expensive than a sparkplug). The resistance is right (about 5 k-ohm per foot; the #4 wire is about two feet long, so the measured resistance of about 12 k-ohm should be acceptable). Perhaps there is a ground-fault somewhere in the wire that occured so soon? I also checked the primary and secondary resistance at the coil. All is well; the primary resistance measured less than one ohm on all terminals and the the secondary resistance measured equally at about 13.5 k-ohms across coil pairs. Any more ignition thoughts?
2. Fuel
I'm going to run some injector cleaner in with the next fill up. Maybe it's a dirty injector? If this doesn't work, I'll remove this injector and more thoroughly clean or replace it (if necessary). I can't think of any more fuel issues which would affect just one cylinder. Maybe a dirty valve? I seafoamed the intake a few months back, so I doubt much carbon has built up in this short amount of time. Should I seafoam again?
3. Compression
I'm nervous about this. If all else fails, I'm going to do a compression check. I don't want to replace rings or a head gasket.
Any thoughts?
ERUSH
Cylinder #4 is misfiring again, so my nifty OBD-2 Laptop hookup says. No codes, active or pending. The subsequent rough idle is slightly annoying, but not nearly as bad a last time. Check out my previous thread for more info on my issues with cylinder #4:
http://www.explorerforum.com/forums/showthread.php?t=225969
Here's my process:
If this was a gross air/fuel/ignition issue, all cylinders would be misfiring or running a bit rough. Since my scanner tells me the misfires only occur on cylinder #4, this narrows down a lot (Vacuum leak, MAF, IAC, EGR, DPFE, etc.), right? Unless there is a slight vacuum leak right at #4's intake. . . what do you think?
1. Ignition:
I just replaced the sparkplug again with little results. I'm reluctant to replace the sparkplug wires again because they are so fresh (and a bit more expensive than a sparkplug). The resistance is right (about 5 k-ohm per foot; the #4 wire is about two feet long, so the measured resistance of about 12 k-ohm should be acceptable). Perhaps there is a ground-fault somewhere in the wire that occured so soon? I also checked the primary and secondary resistance at the coil. All is well; the primary resistance measured less than one ohm on all terminals and the the secondary resistance measured equally at about 13.5 k-ohms across coil pairs. Any more ignition thoughts?
2. Fuel
I'm going to run some injector cleaner in with the next fill up. Maybe it's a dirty injector? If this doesn't work, I'll remove this injector and more thoroughly clean or replace it (if necessary). I can't think of any more fuel issues which would affect just one cylinder. Maybe a dirty valve? I seafoamed the intake a few months back, so I doubt much carbon has built up in this short amount of time. Should I seafoam again?
3. Compression
I'm nervous about this. If all else fails, I'm going to do a compression check. I don't want to replace rings or a head gasket.
Any thoughts?
ERUSH