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Discussion Starter #1 (Edited)
Hi All,

Our 03 ZTS (2.0l DOHC) popped a battery light last week. I troubleshot the problem down to the alternator, and verified this by having it tested before replacement. After installing and a full charge on the battery I fired it up and checked the voltage at the battery - 14.6V running. The car idled down after a short warm up, and nothing showed on a scan of the DTCs. I hopped in the car and drove it around the block. In the first 400ft I noticed a misfire and a loss of power. I turned it around and pulled it back into the garage. I looked it over, and a timing light verified that I had no spark on #2. I fired it up to chevk DTCs and it sputtered and died. I checked again and found spark on only #1, and verified it a second time after going through the other 3 cylinders. Pulled the plugs - still look great (light brown). Checked all wires - all checked good. Both wires and plugs have less than 1500 miles on them after being replaced when the timing belt tensioner gave up the ghost. I pulled the coil and found a huge crack and goop leaking out. Bought a new coil (Motorcraft) and installed it. I checked the wires to the coil (pigtail was replaced when we had the tensioner problem) and the wires to the alt (pigtail also replaced at same time) and both are good. Fuse 10 is good and verified both directions. Both battery cables checked and verified - all connections cleaned. Checked the 3 wire plug to the coil - 12.6V on the center pin and seems to have a changing output on both wires when cranked over (checked with multimeter so verification was not completely accurate). Fired up the car and it idles perfect. Let the car idle for 10 minutes while I checked the voltage at the battery - 14.6V. Got in and ran it down the block, about the same spot it started to misfire again, back to the garage. Pulled the coil and found a crack under the #2/4 plugs in the urethane on the bottom. That's 2 coils that lasted a total of 20 minutes, and I'm stumped as to the cause. I worked as a mechanic for 7 years, and I've never experienced anything like this. I pounded the forums and the TSBs but found nothing that I haven't already checked.

I decided that I'm not putting another coil on until I find a solution to the problem. I hate the idea of sending it to the scrap yard, but I'll be darned if I'm throwing more money at it until I have something more to go on.

I appreciate any feedback or suggestions you might have, thanks for your time!

Bob
 

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Is the coil mount flexing it and causing it to break? Is the coil somehow getting more voltage than it should?

For curiosities sake, are you sure it's a SOHC? I was under the impression that the 'z' in 'zts' stood for zetec. Maybe I made that up
 

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Discussion Starter #3 (Edited)
Crap, you know you're right. It's a DOHC, and I know when I ordered the coil I ordered one for the SOHC. :bang:

Ok, I'll go see if for some reason they are the same, but that's probably a great place to start....

Thanks for straightening me out, I'll be in the back room attempting to kick my own a**.

Bob
 

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Discussion Starter #4
Ok, I checked the coil I bought and by the grace of God it happens to be the right coil for the DOHC 2.0. Now I'm damn confused, after checking the 3 coil wires I have the following:

Ignition off - center pin 13 ohms from ground, other two infinite resistance. No voltage on any of the 3 wires.

Ignition on - center pin at 12.67VDC, other 2 no voltage. Resistance checks from outer 2 wires to ground show infinite resistance (not grounded).

Ignition start - 12.67VDC on center pin, both wires outer wires show no voltage. Resistance checks between the 2 outer wires and ground show connection to ground alternating on both sides. This is what I expected to find as the ground is being switched on an off to each side of the coil to fire the plugs.

I'm at a loss to explain why the coil fried, as we never saw a battery voltage even when running of anything over 14.6VDC.

Bob
 

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Discussion Starter #6
SOLVED - I went back through the wiring from end to end on the car and found that the harness that goes to the MAF and coil had contacted the EGR tube and melted. This caused 2 of the wires to short to ground, and at least 2 of the wires made contact to each other. The wires that grounded and touched are going to the MAF, so I'm not sure how the coils blew. I cut out and repaired the harness and now life is good. With the wire loom on the wires it's really easy to miss the melted wires and loom, so check well before going through what we did. I also added some protection in the form of header wrap around the EGR tube to keep anything like this from happening again.

Bob
 
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