Weird hesitation/miss problems on 97 (long)

S

stones

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Hi, have a 97 Mark. No serious problems with it over the past but sometimes I had a rough idle when it was cold out, and also it seems to be a little slower than what it should.

So recently I swapped the Bosch plugs the existing owner had put in and went to the NGK TR55GP. It looks like I have leaky valve gaskets as there's quite a bit of oil in most of the plug galleys. I cleaned all of them out. I also ripped one of the boots so I replaced that with a Motorcraft coil (DG512).

Now I have this weird miss at idle and also problems accelerating. It seems to hesitate right around 40.

So far I've ordered new Accel brand coils. I think they were $220 for the 8 and should be here tomorrow. Are those generally a good part to put into Fords?

Were the NGKs a bad idea? I generally do not like Bosch plugs. I've used NGK in other DOHC cars I've had in the past (mostly imports) with no problems.

Thanks
 
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Let us know what happens after you install the new coils. Keep your eye on that existing owner, sometimes they are the problem.
 
In case you didn't know, you can purchase the coil BOOTS separately.... you don't NEED to buy the coil with it!
 
I have never had a good experiennce with anything but the Motorcraft plugs in my Fords in the past fifteen years. When I was hot rodding in the 70s, I used Chapmpions in my GTOs, but the modern Ford engine seems to only like the original equipment Motorcraft plug.

I have had no experience with the Accel coils for the 4.6 and I would like to know how well they work. It appears that the price for the Accels is much less expensive than the OE Motorcraft from Ford.

I would be looking at the plugs, and the grounding of the electrical system for the miss. BTW, anytime you have oil in the combustion chamber, it could be causing a miss as well. Leaking oil is never any good. Determine the source of your oil leak, its over $125 a barrel and will cause other problems for you.
 
So far, so good. I just put the Accel coils in and took it for a spin around the block. It seems to be running better now, it didn't miss or skip at all. I still have to take it out on the interstate. The 8 of them were around $275 from Summit w/ overnight shipping. The coils seem close in design to the Motorcraft ones, but strangely they seemed to fit a lot better in the galleys. I think they are a tiny bit shorter than the OEM ones, so there's less slack at the top.

I did a search on markviii.org the day after I bought the single coil and someone mentioned you can just replace the boot. Oops!

I'll post back with the results.
 
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