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Check Engine-cylinder 3/4 Misfire


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9 replies to this topic

#1 PhilB

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Posted 29 February 2004 - 07:54 PM

Okay, I'm stumped...I think.

97 Leg. OB

I replaced headgaskets back over the summer and everything has been good for the most part except: The car had it's moments of kicking on the Check Engine light a few months after the repair. I went to autozone and rented an ODB Scanner and read the codes: cylinders 3/4 misfire. Funny, when the light came on, I was doing 80 and the car didn't seem to skip a beat. Anyway, I reset the code and it kicked on about 30 miles later. I got out, pushed the spark plug boots a little tighter (1 actually seemed to slightly click) and got back in. reset the code and it's been A-OKAY for about 4-5 months. Just recently, the code kicked in again-same thing with cyl. 3/4. I drove it for a couple days until I could get another scanner and, behold, the computer cleared itself! No more code..................for about 20miles. Check Engine, AGAIN, at highway speed and no skip. I drove home, applied some antiseize and reseated all the boots again from plug to coil. Unplugged battery, reset code and VOILA. Clear. Now, I haven't driven it much since but I'm on the edge waiting to see my old friend CHECK ENGINE sometime in the future. Any ideas about the cause? I know I can try new plug wires, plugs, etc. because it may just be some random short but I'm trying not to acquaint mr. VISA with a repair bill this month...and I'd like to know what's behind it rather than stabbing at replacing 1 part at a time..anybody have similar issues?

somebody buy my OB
p

#2 theotherskip

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Posted 29 February 2004 - 08:05 PM

how many miles on the car and how many on the plugs and wires? this is typically a sign that they are starting to age...

#3 PhilB

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Posted 29 February 2004 - 08:10 PM

Sorry I forgot to include car has 147000 miles.
Head gasket job was at 138k,
Plugs have about 5-7k
wires are probably stock original.

p

#4 99obw

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Posted 29 February 2004 - 08:13 PM

I would start by replacing the wires. I replace them every 120k miles or every two plug changes. They are hard to reliably test so periodic replacement is the easiest. I use OEM parts.

#5 theotherskip

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Posted 29 February 2004 - 08:29 PM

yup. you can probably skate by for a little longer, but they are probably on their way out (the wires, that is). are you using the oem plugs? not using them can cause many problems with missed spark, too...

#6 Commuter

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Posted 29 February 2004 - 09:31 PM

If you want to test further, try swapping wires.

Cyl 3 and 4 fire off the same half of the coil pack.

I'd swap wires 3 and 1. And 4 and 2.

If you get a 1/2 cyl misfire, then you know it's the wires.

If it stays with 3/4... it could still be wires, but might be the coil pack. They sometimes develop a small crack that can do things like this from what I've heard.

I have a 97 OB as well. Original coil pack (I think). But I changed the wires to Magnecor a few years back. If you have never changed the wires, you are due. OEM wires are fine.

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#7 1 Lucky Texan

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Posted 01 March 2004 - 12:53 AM

Are the injectors for 3/4 at the end of the fuel circuit? Could be the regulator on the end of the rail is weak. I think swapping the wires is the best idea to really know where to go next.

#8 legacy2.5

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Posted 09 March 2004 - 02:24 PM

I would check the wires first, I had the same problem and my #4 wire was shorting out by the boot on the plug end, which in turn took out my coil pack.

#9 tfarm

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Posted 22 March 2005 - 09:20 AM

Interesting thread. I'm having a similar problem with my '97 OB Legacy wagon, 2.5L. Engine has 132K, just changed the Tbelt, ignition coil, plugs and wires at 128K but the CEL is back on and sometimes flashes. It had a real rough idle and I used Seafoam (last night) which seemed to have cleared it up bit I've only un it 20 miles. I reset the CEL by pulling the battery negative. The light came right back on flashing at first then solid.

I'm tired of spending money on this engine light. Any other cheap suggestions?



I would check the wires first, I had the same problem and my #4 wire was shorting out by the boot on the plug end, which in turn took out my coil pack.



#10 99obw

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Posted 22 March 2005 - 09:30 AM

I would try a compression test based on my recent experience with high-mileage 2.5's that have never had the valves adjusted.

I would pull the codes to see which cylinder is misfiring and see if the compression is lower in that cylinder.

If that doesn't work I would try swapping the injector from a cylinder that is working to the one in question.




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