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Author Topic: Car not running on all 4  (Read 2716 times)

oz-fire

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Car not running on all 4
« on: November 15, 2014, 04:33:21 AM »
I have an N/A Capri project car, that I'm slowly restoring. My problem is that it appears to be running on only three cylinders. Today I replaced the suspect spark plug and lead, however no change. There is plenty of spark to the plug. Any suggestions , where do I look next   
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blueamber

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Re: Car not running on all 4
« Reply #1 on: November 15, 2014, 08:48:22 AM »
What makes you suspect a certain plug? Is it wetter or colored differently from the others?

Best is to perform a compression test.  You can borrow a tester from places like Autozone.

If OK compression then an injector may be malfunctioning.  Keep at it!
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oz-fire

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Re: Car not running on all 4
« Reply #2 on: November 16, 2014, 01:17:19 AM »
When I remove the lead from plug 4 and it makes no difference to the running engine , however when I remove a lead from plugs 1 to 3 the engine revs drop
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blueamber

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Re: Car not running on all 4
« Reply #3 on: November 16, 2014, 09:58:50 AM »
In that case compression test is definitely the next step.  My last Capri with 0 compression had a burnt exhaust valve on #3.  That was my first engine tear-down to head removal, spent lots of hours and about $400 in head work and new valve, new gaskets, new torque wrench, and 12 point socket for head bolt removal...
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mitch1204

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    • 1991 Mercury Capri NA Auto/ 1994 Mercury Capri NA
Re: Car not running on all 4
« Reply #4 on: November 22, 2014, 01:31:14 PM »
Yeah, the machine shop said a couple of my exhaust valves were burnt but he was able to grind and save. It must be a common problem or results of an underlying problem. My head only cost $175 but he's an old friend of mine.

#4 is your suspect. Go to Advance or AutoZone and borrow a compression tester. With 94k my cylinders were all around 141. You'll notice a big difference on #4 from the rest.

The only other thought is to make sure #4 is firing. The easiest way is to hook a timing light to that cylinder or you can pull the plug and ground it. A cracked distributor cap can arc out a particular cylinder. Sometimes you remove the cap and watch inside it as someone cranks the motor. You'll see a blue arc as it carbon tracks. In the dark helps but you can see it in daylight. Hopefully that's your cheaper problem.
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