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Unread 12-24-2007, 08:35 AM   #1
gpJeep
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1999 WJ 
 
Join Date: Aug 2005
Location: north
Posts: 220
testing 4 liter 6 cylinder coil rail

Firstly ---after replacing the camshaft sensor the no code senario became

I have a misfire on cylinder 6 ---p0306 so the camshaft sensor was bad ie multiple partial problems on ignition system !!

plug #6 looks very good but --------- dark colored
other plugs are ok and slight grey- jeep runs on 5 cylinders roughly

no codes for the injectors

I have found that testing the coil rail the resistance should be 15k ohms for the plug side

as I understand it one coil should on the plug side activate 2 plugs - once on ignition , once in the exhaust

There is also on the primary side a plug with 4 pins on the rail - input

I assume one of these plug pins is ground for all the coils the other three pins activate each of the 3 coils as required by the switching transistor or camshaft sensor ?

right so far?

what value should show up on the 4 pin primary side of the coil rail?
ie ground to each coil bank ?


were is the best place to buy a coil rail - dealer , parts place ebay ?

gotta check the compression on cylinder #6


thanks

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Last edited by gpJeep; 12-24-2007 at 11:11 AM..
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Unread 12-24-2007, 09:03 AM   #2
mendelmax
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Join Date: May 2006
Location: Poland, Katowice
Posts: 1,748
As you said, each of 3 coils supply two spark plugs. If it would be coil, it would affect two cylinders, not only one.

Have you checked compression?
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Unread 12-24-2007, 10:20 AM   #3
gpJeep
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1999 WJ 
 
Join Date: Aug 2005
Location: north
Posts: 220
true ----

but I have found other people who have had a single cylinder misfire with a bad coil rail on the internet

go figure ?


Drzekujie ! wesolych swiat

anyone have the specs for the resistance on the primary side?

http://en.allexperts.com/q/Jeep-785/...d-cherokee.htm

Quote:
Fourth one back, starting from the front of the engine. Be sure to check the coil extensions on the end of the rail (the part that attaches to the spark plug) -- they have a tendency to arc to the cylinder head instead of the plug! Too much of that, and the coil rail fails.

is that the funny clicking sound behind the dash board on jeeps that have bad power loss conditions -- ie coil rail firing to ground rather than thru plug ? or rather thru 1 of the 2 plugs ?

result a single cylinder misfire on a bad coil insolator resulting in a bad coil rail eventually

need to test

1 coil rail all resistances as well as crossed ciruit at the mount post to the #6 cyinder test the #6 insolator

Coil pack team cylinder 1 and 6 --- 4.0L 6-CYL. RC12ECC 0.89 mm (.035 in.) or champion 4412 truck plug (very sexy looking)

PRIMARY RESISTANCE
21-27°C (70-80°F)
0.71 - 0.88 Ohms


2 compression test #6 cylinder Carbon on valve ?


Cylinder Compression Pressure
Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.8:1
Pressure Range . . . . . . . . . . . . . 827 to 1,034 kPa
(120 to 150 psi)
Max. Variation Between Cylinders . . . . . 206 kPa
(30 psi)




I also assume that the cranshaft sensor - also replaced is telling me that the crankshaft is not turning enough after the camshaft sensor indicates that current was put to cylinder 6 .... and it therfore misfires
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Last edited by gpJeep; 12-24-2007 at 03:47 PM..
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Unread 12-25-2007, 02:40 PM   #4
gpJeep
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1999 WJ 
 
Join Date: Aug 2005
Location: north
Posts: 220
ok after removing the coil rail this is the results of the test




so on the input side I have
(coil rail to the left 4 input pins on the right) all in the 200 ohm range

pin 1 2.2
pin 2 2.2
pin 3 1.5
pin 4 common ?

on the output side all in the 2000 ohm range about 13.9 - 14.1

does this mean the coil rail is ok ?
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Unread 11-15-2011, 03:43 PM   #5
Fearnsj
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Join Date: May 2006
Location: TN
Posts: 6
Same problem! Grrr

Hello,

I'm having the exact same problem, 0306, checked Ohms across the primary, and secondary but have slightly different results.

Across the primary side all pins have a resistance of 1 ohm across pins 1, 3, and 4 (to each other), and then 1.9 ohms across pin 2 to 1, 3, and 4.

On the secondary side, I have an Out of Limit or O.L. across all of the secondary's to each other which strikes me as odd. Shouldn't the outputs between 1-6, 3-4, & 2-5 have some resistance since they are dual fire?

Anyways, I have changed the plugs, changed the fuel injector which helped alot, now I just have a misfire at idle (instead of all the time), and sometimes it will show up under acceleration, and I have looked at the boot for plug #6 (which didn't show any arcing (that I could see).

Can anyone point me in the right direction? Any help would be greatly appreciated!

Thanks for your time,

Joe

Quote:
Originally Posted by gpJeep View Post
ok after removing the coil rail this is the results of the test




so on the input side I have
(coil rail to the left 4 input pins on the right) all in the 200 ohm range

pin 1 2.2
pin 2 2.2
pin 3 1.5
pin 4 common ?

on the output side all in the 2000 ohm range about 13.9 - 14.1

does this mean the coil rail is ok ?
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