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-   -   coil over plugs\ resistance not 5 ohms/5500 (https://www.ford-trucks.com/forums/452768-coil-over-plugs-resistance-not-5-ohms-5500-a.html)

99FORD EXPY. 01-21-2006 04:14 PM

coil over plugs\ resistance not 5 ohms/5500
 
4. 7.5 ohms on primary/sec.5150
3.1.1ohms pri/5120 sec.
2..7 pri/6010 sec.
1.new

8..5 pri/5205 sec.
7..6 pri/5205 sec.
6..7 pri/5199 sec.
5..6 pri/5242 sec.
need help what range is ok , does it have to be 5 ohms on primary/5500 on secondary PLEASE HELP!!!!!!

thanks in advance

gibsonj 01-23-2006 01:07 PM

My memory from the Haynes specs is somewhere around 0.5-0.8 ohms primary and somewhere around 5K ohms secondary.

All the COPS should be fairly consistent in this range. If you find one that is way out (for example, your #4 at 7.5 ohms primary, if I'm reading your data right), would be inconsistent by a fair amount and would probably throw a misfire code.

Have you scanned to see if any codes are stored?

99FORD EXPY. 01-23-2006 06:13 PM


Originally Posted by gibsonj
My memory from the Haynes specs is somewhere around 0.5-0.8 ohms primary and somewhere around 5K ohms secondary.

All the COPS should be fairly consistent in this range. If you find one that is way out (for example, your #4 at 7.5 ohms primary, if I'm reading your data right), would be inconsistent by a fair amount and would probably throw a misfire code.

Have you scanned to see if any codes are stored?


took it to autozone no codes,I guess I'll just have to buy 6 new cops

projectSHO89 01-23-2006 07:20 PM

The only one that is significantly out of whack is #3 (primary side). FWIW, resistance readings on coils are usually not very helpful unless the coil is either open or shorted.

It would be better to start at the beginning....What the heck are you trying to do?

Steve

99FORD EXPY. 01-23-2006 08:03 PM

It rained pretty hard last wensday thursday morning it had a bad miss

service light came on took it to autozone nothing came up
saterday I changed all plugs and replace bad cop boots and 2 bad cops checked
The Haynes book ,states 5k on primary and 5500 on secondary if the numbers don't match it said replace, can the numbers vary or not. If I don't have to replace them that 300 bucks I can use for fuel

gibsonj 01-24-2006 10:19 AM

Really doubtful that multiple COPS would fail at the same time. You said the CEL came on, but when you scanned it at Autozone, no codes were stored. I'm assuming that your CEL light is now off---correct? Did the Autozone folks re-set it for you?

We really need some more information to help pin this down. Is it running rough all the time, just at start up, during acceleration???? A COP failure should likely throw a code. If no misfires are being detected by the PCM, then I would really hesitate before throwing $50 COP replacements at the problem.

99FORD EXPY. 01-24-2006 07:38 PM


Originally Posted by gibsonj
Really doubtful that multiple COPS would fail at the same time. You said the CEL came on, but when you scanned it at Autozone, no codes were stored. I'm assuming that your CEL light is now off---correct? Did the Autozone folks re-set it for you?

We really need some more information to help pin this down. Is it running rough all the time, just at start up, during acceleration???? A COP failure should likely throw a code. If no misfires are being detected by the PCM, then I would really hesitate before throwing $50 COP replacements at the problem.

The 2 that I replaced didn't fail they had high resistance like 8400,9000k
so I replaced them. CEL light is off, didn't reset Its not running rough now
I just want to know how much can the COPS vary before replacing them

projectSHO89 01-25-2006 08:14 AM

I'd give them 20% +/-, but I still wouldn't replace them based on a resistance test found in an aftermarket manual unless the readings were severely off, like open or shorted as I noted previously.

Steve

gibsonj 01-25-2006 08:34 AM

I agree with PROJECTSHO89. I've seen this much variance comparing resistance across multiple COPS in the vehicle. When one fails, its usually pretty obvious when you test it.

I've also seen misfire codes thrown and it turned out to be the boot insulating the secondary spring between the COP and the plug that had failed. A lot cheaper to replace a $3 boot than a $50 COP.

projectSHO89 01-25-2006 03:59 PM

Add a good size tube of dielectric grease while you're at it to prevent future problems.

Steve


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