My Orginial spark plugs at 85k
12-31-18, 04:50 AM
#16
12-31-18, 05:41 AM
#17
At 62,000 miles (100,000 kilometers) Iridium spark plugs will not show enough gap difference that can even be measured without sophisticated measuring equipment. You said your spark plug gap grew by 28% (0.043 ÷ 0.06 = 0.7167 & 1.0 - 0.7167 = 28.33 or 28%) from factory specifications, which is simply not believable. At twice the mileage (e.g. 120,000 miles) I doubt there would be a 5% gap difference, or a gap of 0.045 vs. 0.043, which is well within factory new specifications of ±0.003.
Maybe Lexus uses better quality iridium spark plugs than what Porsche uses. My 2006 997 Carerra needed replacement at 57k miles. They were so worn caused all kinds of instrument lights to pop on. Dealer took nearly 3 days to find it was the plugs causing all the turmoil.
12-31-18, 06:24 AM
#19
Instructor
I dismiss butt dyno results for anything as innocuous as plug changes. Without a before and after dyno plot, such a person is just another guy with an opinion.
Computer controlled, fuel injected cars will see no degradation in economy. They can't. The computer would through a code if it were misfiring. Plug gap is set so that the compression will not blow out the spark. Today's high energy ignition systems can through a strong spark across a significantly wider gap than spec. To imply otherwise is to not fully understand the relationship between the components.
Computer controlled, fuel injected cars will see no degradation in economy. They can't. The computer would through a code if it were misfiring. Plug gap is set so that the compression will not blow out the spark. Today's high energy ignition systems can through a strong spark across a significantly wider gap than spec. To imply otherwise is to not fully understand the relationship between the components.
12-31-18, 07:52 AM
#20
Instructor
At 62,000 miles (100,000 kilometers) Iridium spark plugs will not show enough gap difference that can even be measured without sophisticated measuring equipment. You said your spark plug gap grew by 28% (0.043 ÷ 0.06 = 0.7167 & 1.0 - 0.7167 = 28.33 or 28%) from factory specifications, which is simply not believable. At twice the mileage (e.g. 120,000 miles) I doubt there would be a 5% gap difference, or a gap of 0.045 vs. 0.043, which is well within factory new specifications of ±0.003.
I dismiss butt dyno results for anything as innocuous as plug changes. Without a before and after dyno plot, such a person is just another guy with an opinion.
Computer controlled, fuel injected cars will see no degradation in economy. They can't. The computer would through a code if it were misfiring. Plug gap is set so that the compression will not blow out the spark. Today's high energy ignition systems can through a strong spark across a significantly wider gap than spec. To imply otherwise is to not fully understand the relationship between the components.
Computer controlled, fuel injected cars will see no degradation in economy. They can't. The computer would through a code if it were misfiring. Plug gap is set so that the compression will not blow out the spark. Today's high energy ignition systems can through a strong spark across a significantly wider gap than spec. To imply otherwise is to not fully understand the relationship between the components.
I've seen first hand improvement in fuel economy and measured gap difference myself from used plugs, so that is what I will go with, not just believe some Joe on the internet. I'm not asking you to believe me either, merely sharing MY experience.
Last edited by er34; 12-31-18 at 08:10 AM.
12-31-18, 08:45 AM
#21
Love those Denso plugs. We just did the 60K service; 60K is nothing for those plugs.
Having said this, I will say the engine feels a little better.
A little stronger at off-idle and low end.
I know these are contradictory statements, but that's my experience.
This is a great car.
Having said this, I will say the engine feels a little better.
A little stronger at off-idle and low end.
I know these are contradictory statements, but that's my experience.
This is a great car.
12-31-18, 09:10 AM
#22
Instructor
Plug gap affects timing. It may not have necessarily reached a point of misfiring to throw a code, but that doesn't mean an increased gap wouldn't begin delaying the spark and in turn affecting the combustion efficiency negatively. It's a gradual degradation.You can deny it all you want, but for the cost of a set of new Iridium plugs(<$100 for 6) - this to me is a no brainer maintenance just like doing regular oil changes.
I've seen first hand improvement in fuel economy and measured gap difference myself from used plugs, so that is what I will go with, not just believe some Joe on the internet. I'm not asking you to believe me either, merely sharing MY experience.
I've seen first hand improvement in fuel economy and measured gap difference myself from used plugs, so that is what I will go with, not just believe some Joe on the internet. I'm not asking you to believe me either, merely sharing MY experience.
The following users liked this post:
highrev6 (12-31-18)
12-31-18, 11:14 AM
#24
After axleback, downpipe, chargepipe, and Bootmod flash and hitting 400+ ponies, spark parks needed to be replaced on the 535iX. Was getting misfiring, rough idling, more turbo lag than usual, and eventual CEL, Replaced with cold tip spark plugs @ 90K. My GS is at 26K and without any power mods on it, I doubt I'll need to replace them before 150 or 200k. Time will tell.
12-31-18, 11:34 AM
#25
After axleback, downpipe, chargepipe, and Bootmod flash and hitting 400+ ponies, spark parks needed to be replaced on the 535iX. Was getting misfiring, rough idling, more turbo lag than usual, and eventual CEL, Replaced with cold tip spark plugs @ 90K. My GS is at 26K and without any power mods on it, I doubt I'll need to replace them before 150 or 200k. Time will tell.
12-31-18, 12:21 PM
#26
12-31-18, 01:05 PM
#27
Instructor
all the comments are great
you dont run plugs for 75, 80 or 85k it makes no sense to own a Lexus product and do it
you dont run plugs for 75, 80 or 85k it makes no sense to own a Lexus product and do it
12-31-18, 04:34 PM
#28
Instructor
The metallurgy, tolerances and better fuel doesn't wear them down like they used to. Oil changes have gone from 3,000 miles to 10,000 miles so a 30K spark plug change should have no trouble going 100K.
12-31-18, 06:01 PM
#29
I think this is on the owner cant argue whos right and wrong some people like to follow the scheduled service like I do. I even change my oil every 5k instead of 10k. if it make you feels good do what you want u know. its ur money and ur car. I even changed diff and tranny fluid too and service manual didn't say change lol
12-31-18, 06:20 PM
#30
Lexus specifies my car to replace spark plugs at 60K. Putnam Lexus did it for me under CPO. They also flushed the brake fluid, which some people never do. But I do...
I will service the transmission and differential, even though it is not manufacturer specified. But I specify it. I bet it smooths out the drive-train.
I will not wait 10K miles to service the engine oil and filter.
I bet Putnam will find our 2008 RX45h oil extremely clean when they service the oil cuz I will change it between the 10K recommended OCI.
All good. And happy NY to all.
I will service the transmission and differential, even though it is not manufacturer specified. But I specify it. I bet it smooths out the drive-train.
I will not wait 10K miles to service the engine oil and filter.
I bet Putnam will find our 2008 RX45h oil extremely clean when they service the oil cuz I will change it between the 10K recommended OCI.
All good. And happy NY to all.