Okay, I have read post after post on spark plugs and now I think I am just more confused. I started looking at the E3 plug responses and I have decided to stay Far Far away from them. I am however confused about heat ranges and possibly killing my motor because of improper heat. Why is the heat range important? How do I know what the heat range of a particular plug is?
I guess I am looking for the recommendation from corvette owners not spark plug manufacturers as to what I should be looking for ?
I have a 6 speed '03 anniversary edition convertible. The only mods are Vararam cold air, B&B shorty headers, SLP catback and a tune from East Coast, which I am very happy with.
over the past 3 tanks of gas I have lost about 2 mpg town and 4-5 mpg hwy. This car is a daily driver and I drive it 26 miles each way to work 6 days a week and anytime I can on the 7th. The speed limits are 45 and 30 and I set the cruise 7-8 mph over the posted speed. I do have a "spirited" trip a couple of times a week in which I do get triple digits I have not noticed any decline in the "seat of the pants"
I have 64000 and some change and I think the plugs are factory ( it had 12000 when I got it in 2010 ). I have also noticed some "blackening" in my tail pipes. (No codes) The idle is still good but I have noticed a little hesitation when I first pull away from a stop when its cold.(within the first 5 miles after startup. 25-30 degree mornings only)
Is this the norm for factory plugs? Should I have already changed them?
I would appreciate any advice on this subject.
Thanks

 

Probably not the plugs. Did the drop in mileage begin right after the tune?

 

no about 20000 + miles later.

 

Are there any codes?

Best guess with not much more info is:

(1) Too cold of spark plugs or..

(2) It is very possible the front O2's are going bad - this happened to me - and this is possible while NOT getting any codes!

Heat ranges on plugs too hot will run way too hot and can ignite the fuel before its time and cause detonation!

Too cold they will foul-out and run like crap, loose mpg and hesitate, leave black suet in the pipes and exhaust!

Now as a suggestion, the plugs for your set-up should be:

NGK TR-55 gaped at .055

What plugs are you running now?

You should be really good with these, one of the best you can run and not expensive!

Thanks,Matt

 

OP, if confused, why not just replace with new, same plug as is in there now? Plug wires original too? Replace them as well.

Many here run the NGK TR5, or TR55. They are copper plugs and won't last 50k miles. There is an irridium version as well

 

I have given thought to same plugs and may do again. The wires were replaced last year at 44007 when I broke one during header installation. It all started when I heard about E3 plugs and started reading about heat ranges. Thanks for the input. I may try the NGK or go back stock. Is there a performance reason to go copper over iridium/platinum or just longevity ?