Car running rough at take-off and acceleration!

9

93LINCMK8

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A couple of weeks ago I'm leaving the dealership and as I step on the gas to go I hear a loud noise and the car starts to run really rough. I pull off to a side street and look under the hood to find that the #3 spark plug blew clean out of the head. WTF?!! A "mechanic" said I could drive it a very short distance like that, but I should disconnect the injector so it doesn't dump fuel into the cylinder. It wouldn't go, it kept cutting out. So I had it towed home where I started to attempt to tap the hole to put a thread repair kit in but the socket wouldn't fit in the hole so I had a mechanic do it. Not the same one that told me I could drive it, although he said that it shouldn't have done any damage since I drove it way less than one mile.

Since it destroyed the connector on the plug wire I bought a new set at AutoZone, along with Bosch Platinum spark plugs. I changed them before I took the car to the mechanic. He told me then that those plugs and wires were junk and to get Autolite, NGK or Denso plugs and wires from the dealer. I told him I was broke so what I got, I got.

He fixed the threads and put it back together. I picked it up and it ran rough. He didn't realize that the injector was unplugged. He plugged it in it ran smooth. Shortly later it started to run rough at take-off and acceleration and down shifting. Seems like only at lower RPM's, but fairly smooth at hard acceleration. Could it be the plugs and wires or a vaccum leak or what. The mechanic swares it's the wires and plugs. It wasn't running like that before the plug blew out of the head! My oh my what ever could it be?
 
My first suspect would be plugs. The mechanic that recommended Autolite, NGK or Denso plugs and wires from the dealer wasn't BSing you.

First test would be to see if you have any codes and start there. The miss could be ignition, fuel or mechanical. It's quite possible a small amount of debris may have been in the cylinder but let's hope not.
 
Thanks for the advice fellas but I got it fixed. When I went to take the wires back to AutoZone I explained the problem to another guy and he told me that the problem was that the 93 MK VIII doesn't put out enough juice to handle platinum plugs. He told me to go to the original equipment Motorcraft plugs. That was it. She runs like a champ now, except for the tranny's wierd shifting problem I mentioned a while back. I haven't got that figured out yet.
 
I have been running platinum plugs for 20k miles in my 98 no problem. Bosch plugs are crap though for our motors.
 
The guy told me that my coil packs only put out 48,000 volts and the platinums need like 100,000. ?? Maybe the 98's have a different ignition system?
 
Yes, the '97-'98 uses a different ignition system from the '93-'96s.

I've never seen the voltage claims before but I suppose it could have merit.
 
93LINCMK8 said:
The guy told me that my coil packs only put out 48,000 volts and the platinums need like 100,000. ?? Maybe the 98's have a different ignition system?
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If you really want to use platinums, you could purchase the Screamin Demon coil packs ($100) from Bill at Supercoupe. Simple swap, and they put out 100,000 volts.
 
Emm I only use platinums... best idle and plug life. Crown Vic uses the same AP764 Autolite plugs... no need to upgrade anything they are OEM equipment.
 
maxmk8 said:
Emm I only use platinums... best idle and plug life. Crown Vic uses the same AP764 Autolite plugs... no need to upgrade anything they are OEM equipment.
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So that service guy's statement that platinums require 100,000 volts is bunk?
 
I don't know what he is talking about or how much the stock Coils put out... but they were designed for platinums which is a fact. And the cars idle just fine when the stock parts are used.
 
the plugs that come in the marks from the factory are single platinums. they even have different plugs on the left and the right side of the motor. im not sure how true this is but ford said that one side fires from the center out and the other side fires from the out side in. shortley after the EDIS set up came out they had a TSB saying that was bs and to use the same plugs on both sides of the motor. the diffrence in the plugs is one had platinum on the ground and the others had the platinum on the center electrode.

the local speed shop here has one of about 10 or 12 spark plug testers in the states and i have seem the diffrence in platinum and copper plugs. i will never run platinums again thay have a super weak spark next to the copper plugs.

on the coils i highley dought that the scpeamin demon coils put out 100k volts as my MSD coils only out out 40k volts. to get much more than that yo would need a MSD type box.
 
7 sek mark said:
on the coils i highley dought that the scpeamin demon coils put out 100k volts as my MSD coils only out out 40k volts. to get much more than that yo would need a MSD type box.
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FWIW the screaming demon coil packs are advertised as "too hot" for stock plug wires. they also say they allow the spark plug gap to be as wide as 0.065".
 
driller said:
FWIW the screaming demon coil packs are advertised as "too hot" for stock plug wires. they also say they allow the spark plug gap to be as wide as 0.065".
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Ughhh...forgot about that, though I myself am running Nology wires, so I'm okay.

I adjusted my 2 steps colder copper plugs to 0.065" gap when I put in the Screamin Demons and the engine runs fantastic.
 
i think my MSD coils call for either .065 or .070 im running MSD wires. i just cant see spending $300+ for a set of plug wires they cant be that good. i was running .055 on my stock coils and wires. to big of a gap on stock coils put a big strain on coils and burn them up but i never had any problems. i did notice a little seat-o-the-pants gain with the MSD coils and wires but it mainley made it start quicker and easer.
 
Well, since I changed the plugs back to Motorcraft OEM, the alternator and battery went to %$#@. I replaced them and it ran OK for a while and now it is back to missing during acceleration. I tried to read the codes but the scanner won't blink, "something needs to be corrected before it can be tested". The scanner book says to look up "no codes" in my service manual, of course, the Haynes manual doesn't tell you %$#@ as usual. What the hell could be possessing my car?!!
 
For one I would use your Haynes book for Kindling material and go on to the Internet and get a copy of the real service manual. I see no connection with you running Motorcraft plugs and wires to messing up a battery and alternator. If you have an Autozone or Advance Auto parts store nearby they can scan for you, and probably give you a print out of any faults that you can report back here with so we can help you. Just as a side note I have seen many an old school back yard mechanic pull the positive wire from a running car as a way to check alternator condition with the notion that if the car still runs it is OK . This practice totally fries out the alternator diodes, so be ware of ever doing this "old school " trick.
 
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I've heard of that too but I'm not inclined to try it. I had Pep Boys check the battery and the alternator and both were bad. I bought a new alternator and borrowed the battery from my buddies old truck, the battery is new. It still misses during acceleration and you can feel it run rough at highway cruising. New Motorcraft plugs, gapped at .054 as per the book, new Duralast wires, new alternator and new battery. WTF!!!
Would the wrong battery make it run rough? It's really only for starting and keeping juice to the alternator, right? It shouldn't make the car run crappy, that is if it is a GOOD battery. Maybe the coil packs are taking a dump on me! How would I test for that?
 
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93LINCMK8 said:
Would the wrong battery make it run rough? It's really only for starting and keeping juice to the alternator, right? It shouldn't make the car run crappy, that is if it is a GOOD battery. Maybe the coil packs are taking a dump on me! How would I test for that?
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As long as the battery is 12 volts, it will be fine for driving.

My next suspicion would be the coil packs, though I'm not sure how to test them.
 
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