Contour Enthusiasts Group Archives Forums General Troubleshooting Duratec hesitation

Greetings,

I'm a long time browser of this very informative site. Looking for some help on a problem I've developed.
I recently changed the plugs in my 99 SE (102,000) to the Autolite pp's (.050). I immediately developed a hesitation at low rpm before the secondaries opened. I researched and blamed the wires so I installed the Ford 9 mm. After each install i reset the pcm, doing this used to get rid of my problem for a day or two. Now, this doesn;t help and the stumble/hesitation has moved to almost any rpm or gear.
The fuel filter has less than 10,000 on it, the air filter was cleaned with the plug wires being changed, and the amount of fuel in the tank has no effect on the severe hesitation. I read in some earlier post about the possibillity of "Bad Plugs" my car never even hiccuped before I changed the plugs, any insight or possible solutions would be greatly appreciated, Thanks

If this is the only thing you worked on, my first guess would be a gap in the connection. All the wires are seated and in the correct tower on the coil pack? Only other way to find this out without removing everything is to get voltage readings from the secondary and see which one(s)is drawing more voltage. Scope comes in handy for this. I guess you got the right heat range of plug and torqued them down to spec...

Originally posted by pctour:

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I recently changed the plugs in my 99 SE (102,000) to the Autolite pp's (.050).

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Check the underside of your hood to be sure, but on my 98SE the gap is supposed to be between .052 and .056, with .054 being ideal. Unless something changed between 98 and 99, I'd say your gap is too narrow.

Try pulling the plugs and regapping to .054.

Pull plugs and regap just as others have said. Too narrow.

I've gapped mine at .54 and my idle is a smooth as silk. No hesitation whatsoever.

Originally posted by todras:

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Pull plugs and regap just as others have said. Too narrow.

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.02" under specs is not going to cause that to happen.

I've had mine gapped at .050 for 14k miles & they are even a step colder.

Yes it is possible you got a batch (or even a couple) bad plugs.

Take them back and have the store swap them under warranty. They should have no problem since they get full credit from the manufacturer (regardless of what some may say) & you are not asking for cash back.
Just tell them exactly what happened. You were replacing your plugs for routine maintenance and immediately after you noticed the misfire and it has become worse.

Thanks for the responses, this is where I stand. Wanting to eliminate or confirm the plugs I purchased the baseline Autolite 764 for the cost, gapped at .054, reset pcm, purrs like a kitten with absolutley no stumble/hesitation. I know our engines require the platinums and will return the others for a swap and try again. On a side note a relative of mine swears that the plugs purchased from a auto parts chain like discount auto are of less quality than those say from NAPA or the dealer, is there any truth to this that anyone knows of? Thanks again

Don't know if there is truth to that or not, but I did want to remind you about the Autolite rebate that ends at the end of the month.

For more info, go to their website.

- Zack

- Check the (bad?) plugs with an Ohmeter. They should be real close; if any read infinity or have very high resistance compared to the others, they are bad.
- Also, sometimes there can be cracks in the ceramic with can cause the plug to short. This happens a lot when they are dropped on the pavement.
- I'd say a given plug is the exact same quality whether sold at KMart or Napa.
- To be on the safe side, remove plugs from aluminum heads only when (overnight) cool. I know, the heads are probably hardened, but I've seen a few plug holes stripped in my life to take any chances. No need to worry about iron heads.

my car has the same problem as this, 3 months ago i changed the plugs and all. but it ran fine then. for the past 3 weeks its been a pain in my ass. it wont rev up like it used to in gear. at first i thought it was the tranny. but im sure its the engine. some times i get a thud that comes from the intake. i asked terry. he said it might be a sticking ISC valve. im gonna clean that as soon as i find it. but i put some water remover in my gas tank and that helped a bit. but the problem still exist, im going to change my fuel filter which is what terry recommended after i told him the water remover helped alittle bit. but now it seems the problem is to to what it was 3 days ago.