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spark plugs

31K views 32 replies 8 participants last post by  Carguy75 
#1 ·
hi guys im new here to this forum must say you guys really know these cars inside out just picked up 2005 fx45 must say its my favorite car ive owned to date the question i had was whats your guys input on ngk iridiums i've tried searching for opinions here but i cant seem to find anyone saying they really like them or not just woundering if anyone here has them and what their input on them is thanks.
 
#2 ·
Platinums are more than adequate and should be changed at 50K v 100K..you will feel it
Do not recommend iridum for any car...GM Powertrain engineers are ademant about that...too harsh a firing plug
Go a range colder too
 
#3 ·
brnjug said:
Platinums are more than adequate and should be changed at 50K v 100K..you will feel it
Do not recommend iridum for any car...GM Powertrain engineers are ademant about that...too harsh a firing plug
Go a range colder too
So what do you recommend? I'm about 60k miles - I should change my spark plugs out w/ new OEM plugs?
 
#5 ·
Conrad wasnt there an old discussion on the fun of changing the plugs on the 45? This thread has got me thinking about changing mine (86k). I seem to remember there were some issues or difficult procedures, or basically just a PITA.
 
#6 ·
As an aside,iridiums are very hard on cats

Cube and a couple of others have done their own...I think an hour or so effort if you have the tools
Do not remember the "fun" thread of this..if you have the manual CD you should be fine
Colder is just to move a step away from detonation,the spark is strong enough to fire a very cold plug
 
#8 ·
Platinums are more than adequate
I noticed less than clean pulls up my test hill to my redline of 7300 in first and 7K in the other gears...fresh plugs,one step colder and it pulled to redline smoothly.As hard as I drive I want that improvement...
 
#11 ·
W/o checking,NGK come in the car and one step colder is stocked by the dealers...but a lot cheaper elsewhere
 
#12 ·
Found this in another thread:

NGK Platinum Spark Plugs:
Gap (Nominal) : 1.1 mm (0.043 in)
Standard type - PLFR5A-11
Cold type - PLFR6A-11
Hot type - PLFR4A-11

NGK Iridium Spark Plugs:
Standard type - LFR5AIX-11
Cold type - LFR6AIX-11
Hot type - LFR4AIX-11

Denso Iridium Spark Plugs:
Standard type - IKH16
Cold type - IKH20

Surprizingly I found the Iridiums for $3 less than the Platinum. Aren't the Iridiums supposed to be "better"? I'm going to stick with the stardard temp, but do you recommend Iridium or Platinum?
 
#13 ·
Would never try to explain pricing

GM Powertrain built my '98 3.8SC Buick and they were adament about not using iridiums(even though that car did not have cats and was also emissions clean-long story,but informative)
Yes,some believe they are great and better.I heed the engineers advice...they brutalize motors to find performance limits and to calibrate motors..They also preached synthetic oil and no need for overhead cams since they could out perform them with pushrods...it was a PR/sales hype,not performance...the more they preached,the more I listened...racing a turbo car,I knew synthetics were a must,but they said everywhere,trans,gears,rear.

Use them if you want to,there is no need,fresh plugs will gain you more...racers change plugs every race day at least...cheap predictable performance
 
#14 ·
I run the copper NGKs in my '02 Trans Am LS1. I know you have to change them more often than the platinum or iridium but they are cheap, just as good, and I don't mind changing them.

Sounds like you are recommending some platinums for my 45? With the miles I put on it, I don't want to have the change them as much as the coppers require.
 
#15 ·
I changed mine at 50K,now 71K and will probably change again before 100K...so not like copper in frequency
 
#20 ·
I run platinum,one range colder(our ignition is more than adequate enough to handle several ranges colder).I have always used the coldest plug available),but not here since MSD does not make anything for our ignition...part of my usual regimen
I do not know anything about the plug you mentioned from the list above other than it is seemly stock temp
 
#22 ·
Sorry,do not know that plug
I use stock gap unless I am trying to address a problem...wider gap for more bottom punch and narrow for more edge against detonation
 
#24 ·
i run iridiums in my 2001 toyota solara. they definitely made a slight difference in response, but i think they contributed to my cat crapping out early. i don't think i'd put iridiums into the fx. there are better ways to crank more power out of this ride.
 
#25 ·
Iridiums spark plugs are great spark plugs to use in the FX. The newer nissans and infiniti's use them as oem now. Toyota recommend them as well and use them in their newer cars. the iridiums have smaller tips that required less voltage for a good spark than most oem double platinum plugs. i believe that the cats wil be fine after using iridiums plugs, there is no such thing as having too much of a aggressive spark in a combustion chamber. Remember the honda racers and hot rodders who used MSD coils to get a stronger spark? A stronger spark will only give you more power and better mpg. Double platinum plugs will probably last longer due to have platinum on the tip and ground electrode, but platinum plugs are not really a performance plug even compared to copper plugs. they are good for people who do not want to change their plugs for 100k+ miles. If you do not care about changing your plugs every 60K miles or so, iridiums will give you the best performance and economy. I personally use Denso iridium power plugs in my 04 FX45 which have a very small firing tip, and my mpg is great over 16 in the city with stop an go traffic stops. I used to get only about 11-13mpg in those conditions. do not believe myths about damaging cats and too aggressive of a spark plug. Use them and see for your self.
 
#26 ·
And you are digging up a topic from 3 years ago because.... :?
 
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