5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

Better ground wire?

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Old 06-20-2005, 07:04 AM
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HungLow5.0
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Default Better ground wire?

When I rev my engine over 2,000 rpm and push the clutch in so it goes back down to idle, it stops around 1,000 rpms for a few seconds than goes to my idle at 700. When it hits my idle, my volt meter goes way down. I was talking to one of my friends about this and he said he had the same problem and he just put another ground wire from the block to the chassis. Would this fix this? if not, how can i fix it? Thanks
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Old 06-20-2005, 09:36 AM
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Quik
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Default RE: Better ground wire?

The "ten pin" connectors are these salt and pepper shaker looking things found at the back of 5.0L engines -between the intake manifold and firewall. These connectors are notorious for developing poor connections and causing strange EEC quirks, like idle fluctuations, check engine lights, and unexplainable diagnostic codes to be triggered. On many Mustangs there may be a dealer installed extension harnesses, making it appear as if there are a total of four of these connectors.

Every owner of a 5.0L EEC-IV controlled engine has probably experienced, or one day will, the dreaded "idle surge". Ford terms it the rolling idle, but either way its annoying as hell to watch the idle stick at 1500, then drop to 700, then float to 1000 and so on. Or perhaps you've just got strange and annoying EEC gremlins and you're at wits end. Well we've got one other thing to check out before you roll your car off a clif, the ten pin connectors.

Always start by checking the basics: vacuum leaks, throttle position sensor voltage, resetting idle, and pulling codes.

Once all these ideas are checked out and crossed off the list, check the ten-pin connectors on the main harness. These connectors are notorious for developing loose contacts. Ford even issued a TSB on some model years, and dealers installed an "extension harness", thinking perhaps the original harness was too short causing the large connectors to pull apart. The fix below is simple enough to perform, and should be done as a preventative measure even if you dont have surging problems.

It may be a long shot in solving your problems but its not a bad idea, and another thing to check off your troubleshooting list.


1. Disconnect the negative battery cable! To open the connectors squeeze the four side clips and pull apart. Do not pry the clips apart as with other connectors. The inner workings reveals ten male and female connectors.





2. Using a nail or sharp punch spread the male connectors open just slightly. This will ensure a complete contact. If you open up the ends too much use needle nose plier to sneeze the "leafs" back together.



Before reassembly take some spray electrical contact cleaner and clean the male and female connectors. FM
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Old 06-21-2005, 03:26 PM
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HungLow5.0
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Default RE: Better ground wire?

thanks, i'll give it a shot
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Old 06-21-2005, 04:26 PM
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Default RE: Better ground wire?

yep, hopefully that helps you out
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