missing after tune up
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Junior User
Joined: Oct 2004
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From: China Spring, TX (Waco)
missing after tune up
Just aquired a '93 Explorer with 208K on the clock. Ran fine with original coil and plug wires on it. Had a new set of Bosch plug wire to put on it so decided to do a tune up. Pulled the plugs and they were worn out (don't know how many miles on them) and looked as if they were running lean. Bought a new set of Autolite 764's which is one heat range cooler than OEM plugs, gapped them to .052" and installed them and the new wires. Now it appears to be missing on one or more cylinders. Idles alittle rough, and you can hear the miss at the tailpipe.
Ran it up and down the street, pulled the plugs and it looked like #2 was not firing. Thought maybe a bad(new) plug. Swapped #2 and #4 and put the original #2 wire back on it. Still missed. Went and bought a new coil, installed it and put the new bosch #2 wire back on it. Still misses. Ran it up and down the street, pulled the plugs and they look all the same.
Besides not fixing what ain't broke, what am I missing. Checked/rechecked plug wire firing order, electrical connections. Is a .052" gap too much for a standard type plug? Heat range too cold?
cds
Ran it up and down the street, pulled the plugs and it looked like #2 was not firing. Thought maybe a bad(new) plug. Swapped #2 and #4 and put the original #2 wire back on it. Still missed. Went and bought a new coil, installed it and put the new bosch #2 wire back on it. Still misses. Ran it up and down the street, pulled the plugs and they look all the same.
Besides not fixing what ain't broke, what am I missing. Checked/rechecked plug wire firing order, electrical connections. Is a .052" gap too much for a standard type plug? Heat range too cold?
cds
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Junior User
Joined: Oct 2004
Posts: 93
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From: China Spring, TX (Waco)
I have the plug wires attached to the coil just like it is marked and terminate at the corresponding cylinder following Ford's numbering convention (same as shown on post above). I also connected a timing light to each plug wire to see if it would trigger a response (strobe) which each one did. I know that doesn't necessarily mean that coil voltage is in fact reaching the plug, but it was the other thing I could think of to check.
Any other thoughts on the pluge or wires?
Any other thoughts on the pluge or wires?
Elder User
Joined: Aug 2001
Posts: 942
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From: South Texas
Take a good look at plug/wire for cylinder 6. The coil fires both 2 and 6 together regardless of which is on the compression stroke. (The mate is on exhaust stroke so no problem) Both paths must be good to get a good spark at each.
Dialtone
Dialtone
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Junior User
Joined: Oct 2004
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From: China Spring, TX (Waco)
After the last test drive, all the plugs looked good. Since all the plugs are out now, I'm going to do a compression check (should have nothing to do with the current problem since everything was fine before the "tune up" and I'm quite sure nothing mechanical has happened since) and then will check the EDIS wiring to make sure a pin connector didn't get bent or something. As Dailtone mentioned, a problem with #2 should mean a problem with #6 as well (like no signal/power to that coil).
Thanks to all for the help. Will keep you posted.
cds
Thanks to all for the help. Will keep you posted.
cds
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Junior User
Joined: Oct 2004
Posts: 93
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From: China Spring, TX (Waco)
Update on miss
Thought I had a problem not getting fire to one or more cylinders based on a discoloration of the number two plug. Put in some new Autolite 765 platinums and it still missed. Started tracing wires on the harnesses to see if I had pulled something loose or broke a wire and sure enough, buried underneath the radiator hose, the #1 fuel injector connector had pulled off. Plugged it back in and it was off to the races (well maybe not that good, but no more miss).
Thanks again for the inputs. This forum is one of the best I used for getting technical help.
carl
'87 ranger
'93 stang
'93 explorer
'94 club wagon
'96 bronco
Thanks again for the inputs. This forum is one of the best I used for getting technical help.
carl
'87 ranger
'93 stang
'93 explorer
'94 club wagon
'96 bronco
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