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Discussion Starter #1
I put new motocraft plugs and wires on my 92 SC for a tune up. Now it has a horrible miss under boost pressue above 8 psi. Plugs are gapped to. 054, and for sure all the wires are on tight. The car idles smooth and at 5000 rpm it runs good, its just at higher boost levels it does this. The car ran fine at higher boost levels before the tune up. The only mods to the car are a 10% od pulley on the s/c and a 255 fuel pump.

Any suggestions
 

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I put new motocraft plugs and wires on my 92 SC for a tune up. Now it has a horrible miss under boost pressue above 8 psi. Plugs are gapped to. 054, and for sure all the wires are on tight. The car idles smooth and at 5000 rpm it runs good, its just at higher boost levels it does this. The car ran fine at higher boost levels before the tune up. The only mods to the car are a 10% od pulley on the s/c and a 255 fuel pump.

Any suggestions

As far as i can tell from what I have read at SCCoA, that gap is a little big. that is the MAX factory gap. Under higher boost levels they cannot hold up. I would try to gap them to like .040-.045 and see what happens. Here is a good thread that might helphttp://www.sccoa.com/forums/showthread.php?t=89983&highlight=plug+gap
 

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Discussion Starter #4 (Edited)
The old plugs were gapped to .054 when I put them in and I never had this problem. They were in there for 4 years, so i measured them and some of them had a gap of .061. Could a bad plug or wire cause my problem. My max pressure is 14 psi
 

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Change to your plugs Autolite 764's, and get rid of that 10% pulley. It is harming you more than doing good, because the IAT's are causing the knock sensor to retard the timing. You need to change to a cooler plug, the 764's effectively act like a cooler plug because they don't extend as far into the combustion chamber. If you want to go the next step switch to the Autolite 103 which is effectively 2 ranges colder. There is a FAQ on spark plugs on the SCCoA forums, check there for more data on this subject.
 

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Discussion Starter #6
Thanks for the info, I'll try regapping the plugs first, then I'll try the different plugs and see what happens
 

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I was having the same problem, I placed new plugs in my 93 SC and it was missing at higher RPMs I pulled the plugs and they were all gaped at .045 so I gapped them at .054 like ford says. It now runs a little better but still missing some. If all the plugs are gapped at the same size I was told it would make a big difference.

So then I replaced the coil pack and it solved my issue, coil packs are $125 or $175 for the accel brand I went to the junk yard and found one for $25.

You also might want to take your DIS module off and remove the old thermal grease off it and replace it with a new coat, I use some arctic silver used on computer heat sinks. Good stuff.

I hope I helped,
Jerry V.
 
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