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95 Explorer plugs

My explorer just started to run a bit rough on idle. It has 110,00 burns no oil and is mint condition.

I bought some cheap copper core plugs and changed just one plug to see how bad the old ones looked. Wow the old ones had a gap that was huge, like over .9 they call for .54. I started the car with just one new plug in and it idled great!

I'm thinking just how much better it would run with all six changed.

Insted of putting the cheap plugs in I decided to try AC #14 (the zone said my truck could use #5 or 14, 14 is hotter I guess)

Anyway I gapped the rapid fires at .54 and put them in along with new plug wires.

I start it up expecting super smooth idle, no way it idles like it did before I changed the plugs.

I looked up the rapid fire specs and they say to gap at .60 on my car. I gapped them at .54 as the manual says.

Could that narrow gap make it idle rough?

I tried to locate which plug was misfiring by pulling plugs off the distributor. It was really hard to tell as it does not run that bad on 5 cylinders.

So why is it idling rough?

  1. One of the plugs is misfiring
  2. One of the new plug wires is bad
  3. The rapid fire plug are all misgapped.

The plugs that came in my truck are Motorcraft Platinum 42PG.

At first I purchased a 6 Autolite 765 copper cores. I put one autolite in cylinder #6 and it idled super smooth. But that was with the old plug wires.

I noticed the distrubutor cap has plugs on left side numbered

3 4 2 6 1left side 5 Right side of cap

Notice how they have #6 in the middle of 4 and 5 vs the left side where they are in order. This may be just the way the cap is made. but I'm thinking did I switch the wires?

Any help is appreciated. I don't want to pull off all the plugs if I don't have to, I have bloody knuckles from the first time :)

Reply to
Robert Jones
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Assuming that you do not have a diagnostic tachometer or a timing light with which to look for a misfire, you might try lightly squirting a very small amount of water onto the exhaust manifolds at each exhaust port. A misfiring cylinder will be indicated by the water vaporizing more slowly than on a firing cyl.

And just my own (arguably worthless) > My explorer just started to run a bit rough on idle. It has 110,00

--snip for space--

Reply to
Marky

Are the wires still original? If so, they might have been fragile enough for one of them to get damaged when you changed the plugs. Happened to me a while ago, and the vehicle was only two years old at the time. I don't replace a part unless I know for sure it's bad, but if your wires are 9 years old, it may not be such a bad idea, especially if you don't have a scope to identify the misfiring cylinder. Other than substituting a 'known good' wire, I don't know of a simple way to diagnose them.

IK

Reply to
IK

The wires were all new.

I am going to change all the plugs again bust some knuckles on the way :(

Thanks for the input.

How much are scopes that could help diagnose it?

Reply to
Robert Jones

Scopes are way out of the price range for anyone that does not do electrical/automotive diagnostic work as a profession. A hand-held graphing meter, such as Snap-On's Vantage, runs about $2300 (vaselene not included). A true oscilloscope can be much more.

FWIW, a simple multimeter (anywhere from $10 at kmart for a cheapie analog to several hundred for a good digital) can check the plug wires. A good rule of thumb is that resistance of a plug wire should never exceed 5 kohm per foot, and much less is preferred. A voltmeter should *never* be used to check for voltage on a plug wire while cranking/running the engine, as secondary ignition voltage is quite high, nearly 80,000 volts in the case of some DIS systems. It's hard to get seriously injured/killed from getting zapped, but this hurts pretty good and the meter will get fried. After disabling the fuel pump or FI system (pull some fuses), remove a wire from a plug, insert an extra plug, and hold it against a good ground while cranking the engine. A blue spark should jump between the electrodes. This method, used on each plug wire, will virtually eliminate the ign system as the culprit to a misfire condition.

All po> The wires were all new.

Reply to
Marky

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