Can anyone recommend which spark plugs i should by? I have an 03 GT just hit 75K and plan on replacing plugs with coils in the next month. Current mods being flowmaster cat back. i plan on installing CAI, headers, mid pipe, throttle body and hopefully a custom tune over the next 6-8 months.

 

i put the e3 in mine and they work great

 

I just installed NGK TR55s and so far so good.

 

stock motorcraft, why pay more when you dont need to?

 

^+1, or Champion stk # 3401--basically the same, a single platinum plug--there is nothing you are planning (of for that matter on almost any streetable 4.6 2V) that requires anything else...

 

Cliffy...when I was searching around myself on this same question I read a lot of places saying to run 1 step cooler plugs gapped at .054". They said they can get more timing out of a cooler plug and "the car likes a cooler plug"...at truth?

 

I've always run either Motorcraft Platinums or Bosch Platinum +4's...though most here tell you to avoid the Bosch's... I've never had any problems with them.

Just don't buy bargin bin "Bob's Spark Plugs" and you should be fine.

 

One word.


Motorcraft cant go wrong with OEM's

stay away from the Bosch Platinum +4's ..theyre junk !!! Sorry crysalis but I had very bad experience with them. Plus theyre not made for our cars.

 

It depends on whether or not the stock heat range plugs are running too hot--this can easily be determined by "reading" them after making one or more runs at the throttle setting/range you are targeting. To do it properly you make the run and then shut down the engine, stop and pull the plugs--we did this all the time on drag bikes way back when there was no other way of electronically monitoring anything.

There are colour charts out there that have been around for years, most of them are incorrect for modern EFI engines where the plugs should be a bit lighter tan than most charts show.

As to a cooler plug's offering an opportunity to run a bit more advance, it might; however unless the original plugs were way too hot (nearly white looking) the gain would be quite minimal. If the original plugs were of a proper heats range you would perhaps lose a bit of MPG with no power gain at all.

One other comment, there is no standard for heat range classification of spark plugs, neither a general range or steps between ranges--each maker uses their own scale to rate their plugs, and provide cross references to other maker's plugs. So, just because NGK says that there heat range X is the equivalent to Motorcraft's Y doesn't mean it's an exact match.

This is particularly true when comparing fine-wire and conventional electrode designs where the heat dispersal characteristics of the two designs are quite dissimilar.

 

I've been running autolites since the dawn my drivers liscense, no issues.