[B3NN3TT]

Okay. I just put in a fresh set of Autolite plats a couple of weeks ago. Since then I've gotten 2 CEL's, the car pings uncontrollably, and my fuel economy has gone down the toilet. So tonight I decide to put my old plugs back in, to see if things stabilize.

Midway through the job, I stop to take a look at the plugs, and notice that they are really quite different. I have attached a photo or 2 to explain. The Autolites have about 1/2" of threaded area around the electrode. The old plugs (Splitfires) are threaded almost all the way up to the nut. So this begs the question: were the Splitfires seated all the way to the nut, and getting MUCH deeper into the combustion chamber than the Autolites? Or do they stop before they reach the end of the thread?

I've not finished puting the Splits back in yet, but they did fine for a good many miles. So I'll be testing them out later.

But that geometry really bothers me. Why are they different? Is that good or bad? Which is better?

 

[JohnnyRed]

wow, that is quite a difference......I'm guessing those might not be for our car. I'm gonna go on a limb here and say that is your problem. Let us know.

 

[pgtatx]

what's the part number on the Autolites you got??

 

[99CouGSweetRide]

Hmm...those are the right ones...AP764. I just installed those at the end of October and my car's been running great. I'm not positive about this, but by looking at that second pic, it kind of looks like your gap is way off. It should be .054. As for that threaded part, I don't even think my Motorcraft plugs had threads that long.

Mike

 

[B3NN3TT]

Gap is correct. I think that's just an illusion in the photo.

Too soon to say if putting the splits back in has fixed anything yet, but I'll keep updates coming.

BTW, I still had my old OLD Motorcrafts sitting on a shelf, and I checked tham. The thread on the Motorcraft is the same as the Autolite.

 

[99CouGSweetRide]

Yea thought I didn't notice a difference in the threads between the motorcraft and autolites. The only thing is to just double check everything I guess...make sure the wires are correct, the gap is perfect...i don't know what else. I know when putting the wires back on the rear plugs I had to press it down really good for it to pop on, cuz it was a little tight back there.

Mike

 

[eurocrisp]

The threads arent the problem. I guarantee they seated properly. I think i read somewhere that the reason that portion of what could be threaded area isnt threaded is so they could be used more efficiently in robot assembly lines, ...or something...

Did you get the CEL's diagnosed?? are you sure you 'snapped' the rubber things on properly?

like mike said, just go back and double check _everything_. i remember I took apart something little grounded something or other on the coilpack that i didnt need to take apart & i almost neglected to put it back.

 

[B3NN3TT]

Okay!

The fuel economy still sucks. HOWEVER - I failed to realize that I changed the plugs out at the beginning of the cold snap, so there's the reason for that right there.

The CEL's turned out to be unrelated - O2 sensor stuff. It has since gone out on its own. (?)

The car still pings kinda bad. I Techronned it last month; perhaps I'll need to do that again. Any other thoughts on the pinging problem? Could this be related to carbon buildup? GM makes a combustion chamber cleaner that you jet into your intake (like Nitrous), that burns all the carbon out of your cylinders and frees up the rings if they are frozen. I'm tempted to try that stuff...

 

[BrantlyJ]

for the plugs. As youy can see the seatis in the same place as both plugs. Once it hits that seat regardless of how much thread there is it won't go any farther.

Your pinging could very well be carbon buildup. What happens is if you get enough carbon it will actually get so hot it glows red. AS the piston goes up compressing the fuel it goes off like a diesel.

I don't know how much that GM stuff is but it's probably made buy Seafoam. And you can get that for $4-5 a can. Or you could use water. Just get a spray bottle and squirt some in while the engine is running. Be prepared to buy a new cat though. I did this on my old Cavalier and it had so much carbon that it actually broke off in chunks went through the headers and proceded to plug my cat. The mechanic that replaced it said that when he took it off about a half cup of carbon flakes fell out. Luckily the cat was in warranty.

 

[JohnnyRed]

Did you say spray water in your intake??? I would be scared to death doing this. Please explain how this is safe.

 

[BrantlyJ]

well your not dumping a gallon of water in there at a time. Like I said use a spray bottle and spray it in. What happens is the water turns to steam which in turn softens the carbon and it falls off. I do it all the time on my motorcycle and it works great.

 

[B3NN3TT]

Yep, I've heard of that done a lot. If you mist in water in small quantities, it effectively steam-cleans your cylinders and piston heads, ring lands, valves, the lot. Really! I'll prolly do that, but I figured the seafoam or whatever would do a better job.