Do you recommend these plugs?

[Phlip77]

Hello All,

So I've been cleaning out the closet and tool boxes and I found spark plugs that I purchased previously for my 05 Grand Prix GT. The plugs are NGK TR55GP (Stock number 3403).

I no longer have the car as I've gone to an 05 Grand Prix GXP. Would these plugs be ok for the car? Or would you recommend I sell them and use something more suited for the GXP?

Thanks

[matt5112]

They'll be fine.

The second five only means they were pregapped to .059" before shipping.

Bring that down to 0.040" and you'll be fine.

[Phlip77]

They'll be fine.

The second five only means they were pregapped to .059" before shipping.

Bring that down to 0.040" and you'll be fine.

Thanks Matt, good to know

[91parkave]

Whoa you need NGK tr6 plugs man not tr55 and the gap will be .35

[matt5112]

Rock auto suggests TR5 at 0.040.

Why are you suggesting a colder plug and a smaller gap?

[91parkave]

Rockauto has garbage for specs and catalog errors are abundant. Look on Ls1 tech if you want accurate plug info for LS motors tr6 plugs are colder than stock and come highly recommended for n/a apps

[matt5112]

Why would you use colder plugs on an engine that you haven't changed compression or added boost to?

http://www.ngksparkplugs.com/part_fi...uv/default.asp

NGKs catalog agrees with the RockAuto listing.

LS1 Tech has just as much bad information as it does good information. It is by no means a definitive source.

[91parkave]

No but what of does have is people with LS engines that know a lot more than you or I. I wouldn't be running that plug if it was just some random dudes advice. Look under the ls4 section on tech.

[TLSheff]

I'm no specialist with these motors or LSx motors... but I will settle this as only a GM Parts Guy can. Both the L32 and the LS4 use the same iridium spark plug, a 41-110 (GM# 12621258). The TR55 is a direct replacement for either plug... slightly cooler but a direct replacement. So GAP the plugs down to the right specs for the LS4 and you should be golden.

[Phlip77]

I will def do some more research. Wasn't sure, as I bought these plugs for the 2005 Grand Prix GT at the time. However I wanted some more power to the ground and a little rumble and changed up to a GXP.

[The Guz]

You can use either plug. GM changed the plug use back in 05. I have an 02 Camaro with an LS1 and will be switching to the new plug gap. My dad switched his out on his 02 Camaro with an LS1 to the ew plug gap. The car runs great. Mods on both cars are intake and exhaust.


This should help. Courtesy of NGK on maryland speed's site.

What GAP to use?

Prior to 2005 GM used .055 GAP spark plugs on all LSx motors. Starting in 2005, they switched to .040 GAP (this size) plugs to provide a better idle when things like cheap gas are encountered. Any LS2, LS3, L99, or LS7 will come from the factory with a .040 GAP

This tip is an upgrade over the standard LSx style plugs with better design and performance qualities.

Improved Fuel Efficiency, Lower Emissions, Quicker Starts.

•Fine platinum tip reduces required voltage
•Extremely durable under high heat
•“Trivalent Metal Plating” has superior anti-corrosion and anti-seizing properties
•Faster starts and quicker acceleration
•Better fuel economy and lower emissions
•Best platinum spark plug at an economical cost
Fits most GM LSX (LS1, LS2, LS3, LS6, LS7 etc) applications.

[matt5112]

IIRC, the older factory plugs had pucks that fell off and the gap got much larger, causing misfires.

Replacing them for non puck ground straps was a thing for a while there.