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Old 07-11-2008, 12:20 AM   #1
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Default Odd problem with COPS

So for some reason randomly when im driving the car will spudder (sounds and feels like its running on 2 cylinders), and the tach jumps down and shows half the actual RPM. It will do this for a sec, then be fine, then do it for another sec, then be fine for hours, then do it some more.

I dunno what it is, my wireing is good..
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Old 07-11-2008, 12:33 AM   #2
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its a miss.
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Old 07-11-2008, 05:30 AM   #3
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I had this problem, turns out that the earth was faulty on one set of COPs.

I measured everything on the harness and it was all fine on the DMM. Turns out that one of the little the little spring loaded sockets in the plug was deformed and not making proper contact with its appropriate pin and the vibrations whilst driving would cause it to disconnect for a brief moment causing the exact symptoms you described.

Mine eventually failed completely whilst overtaking a truck on the motorway at over 100. Whoo that was fun. But it did help me identify the problem. Untill then I thought I had cooked one or more of my COPs buy running them with the stock ECU.
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Old 07-11-2008, 04:38 PM   #4
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Is there any way to make the coil to spark plug connection better? I think that might be my problem too.

Quote:
Originally Posted by Duckie_uk View Post
I had this problem, turns out that the earth was faulty on one set of COPs.

I measured everything on the harness and it was all fine on the DMM. Turns out that one of the little the little spring loaded sockets in the plug was deformed and not making proper contact with its appropriate pin and the vibrations whilst driving would cause it to disconnect for a brief moment causing the exact symptoms you described.

Mine eventually failed completely whilst overtaking a truck on the motorway at over 100. Whoo that was fun. But it did help me identify the problem. Untill then I thought I had cooked one or more of my COPs buy running them with the stock ECU.
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Old 07-11-2008, 04:41 PM   #5
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no one else is having these issues.... what gap plugs?
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Old 07-11-2008, 04:51 PM   #6
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Cardriver, it wasn't the connection between the coil and the plug it was where my homebrew harness plugged into the factory wiring. When I prototyped the install I just poked wires covered in solder into the plugs on the factory wiring this deformed the "female pins" for want of a better word. I spent 2 hours on the side of the road in the pissing rain poking the plugs with a tooth pick to get it working again.

In your case it would be where the ignitor connects to the harness. Try adding an additional GND and +12v see if that helps.

Brain, I was using stock gapped NGK plugs. No probs since sorting out the dodgy connections.
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Old 07-11-2008, 08:28 PM   #7
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I know my harness connections are good, I hard wired them into the car. I am suspecting it may be the connections for one of the coil packs thats causeing it.. ill have to do some checking i guess.

stock gap NGK plugs.
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Old 07-11-2008, 08:39 PM   #8
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Happy hunting. Check the "female pins" for the connectors on each COP. Check the resistance of the primary winding on a COP by running a DMM over the pins. Then measure the resistance again by putting the DMM probes on the wires from each connector. This will tell you how much resistance you are seeing over the connector and whilst you are there wiggle any and all connectors/splices to see if you get "drop outs" in the meter reading. Be sure and test them one at a time beacuse 2 identical resistances in parrallel will be half of the original resistance.
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Old 07-13-2008, 09:38 AM   #9
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Quote:
Originally Posted by Duckie_uk View Post
"female pins" for want of a better word.
female sockets or contacts?
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Old 07-13-2008, 05:10 PM   #10
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I think I fixed it, seems the carpet on the pasenger side was pushing on the wires that connect to the MS causing it to mess up... DUH.
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Old 07-13-2008, 05:37 PM   #11
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It was always gonna be something simple. Glad you found it
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