it occurred to me the other day that after all the mods, spending thousands of $$$ and 25k miles that i had never even pulled a plug on my car to take a look at it. (i am sure most of you have but i had not)

so last week i started a thread on which plug to use, proper gap and so on. last night i picked up the plugs from the auto store and got to work.

sorry for the long story but here is the part i found interesting. 8 out of 8 of my plugs were gapped incorrectly. again lots of mods, tons of $$, car in and out of a professional shop and a basic of basics was never looked at or discovered.

7 plugs were between .035 - .037 (running a bit lean and on white side)and 1 plug was at .064. (of course this last plug was a bit darker than the rest but still not horrible) so i set all 8 new plugs at .040 and a few minutes later they were in.

now i have never been one to listen to or believe claims of power gains from spark plugs but in my case it is understandable since all my plugs were set wrong. after the change i expected (prayed) that my car would run a little better but i had no idea what a difference it would make. you guys do not know me but i am not a "big mouth" guy but this thing is making more power everywhere!! i really could not believe the difference it made. (anyone who is now saying "you can not be sure unless you put it on the dyno" is 100% correct. however i am telling you i can actually feel a difference)

i even picked up a little surging at around 2,000 rpm. i recently had a cam installed and it was tuned so well that i had no surging at all and now i have a little. i am thinking of returning to the shop for a re tune to eliminate the slight surging but do not want this new found power tuned out.

anyway there is my ridiculous story. i did not mention the brand of plugs so no one thinks i am making some silly claim on behalf of this brand. i can only report what happened to me thinking there may be one other forum member out there that may also benefit from this report.

tks for your time, dal

 

Your claim is not far fetched. Bad plugs or incorrectly gapped plugs do have an impact on power and efficiency. If nothing was disconnected/broken in the process, the surgin could be too lean/too rich a mixture as things inside the chambers have suddenly changed. Disconnect the battery to reset the PCM. Drive the car for a few hundred miles before re-tuning.

Rick

 

I missed your other post. What plugs did you go with?

 

I think I'll go outside and check my sparkplugs . Thanks

 

i went with the NGK TR5 iX. however i must report that these are supposed to come pre set at .040 "ready to install" and 8 out of 8 of these were not gapped correctly either. they also were gapped between .035 - .037 and required slight re gapping prior to install.

since this is what my old plugs were gapped at i thought my guage may be wrong. so i used two diffent guages to check gap on all plugs (old and new) just to make certain all gaps were correct. one of those cheap sliding guages and one set of fealer guages. (not sure if i am saying or spelling that correctly)

 

That's very interesting because we do over look stuff like that trying to add big horsepower and wonder why our vettes are not making full horsepower like other vettes with the same mods, this maybe part of the problem.

 

in all fairness, i have to say if i had just taken out my old plugs, cleaned them, re gapped them and put them back, i probably would have still felt an improvement. however for $55.00 and no additional labor why not put in a fresh set and get every ounce you can get?

 

The plug with the larger gap, that didn't happen to be in hole 7 or 8 did it???

Randy

 

I too just replaced plugs and wires on my 08, with 8000 miles on the ODO. I found two of the stock plugs, gapped at .055 & .058. The others were all over .040. My idle is much smoother, and part throttle response is improved. I used TR6ix, which are one step cooler, with MSD superconductor wires.

 

hi Randy,

sorry i am not savvy or literate on just giving a hole no. so i will have to describe locatiion. if sitting in car it is the one on passenger side front of car. (furthest from the fire wall).

tks, dal

 

hey Randy,

i have a question for you since i see you are a supporting tuner..
what do you make of the slight surging now at around 2,000 rpms? (and it is slight) do i have to get car retuned or will it "learn" to compensate or fix itself for lack of a better term.

tks, doug

 

ALWAYS check gap and ceramic on any new plugs, even if they are supposed to be "set".......

SR

 

Yep, both of mine with the larger gap were in 7 & 8..?????

 

That would be hole number 2.

7 and 8 are known problems in the LS engines and I was curious if the shop did the spark plug gap "wrong" for a reason. It sounds like it was completely random.

Randy

 

Did they look worn more or like they were done that way.

Randy

 

I kind of thought that, 7&8 usually run a little lean don't they? The electrodes didn't look bad, just the gap was wide..

 

IT can be a million different things. Try unplugging the battery like suggested and start the learn process over. If that doesn't fix it, bring it to your tunner.

Randy
PS I'm not the tunner here at the shop, I do sales, some fab and welding work, plus clean the bathroom

 

 

Plugs off the shelf are never gapped as advertised, I seriously doubt the nice folks in BG check the gaps on plugs from the supplier.

That reminds me.... I need to go check my plug gaps

 

The LS engine is pretty forgiving on plug gap. It will tollerate a LOT of varience. Given the fact that you have modifications to the engine, makes plug gap a little more significant.

Glad you have it all worked out.

BC