1UZFE Spark Plugs
#1
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Guys - Many wonder about what spark plugs are recommended for our 1UZFE's, when to change them, how to tell if they are bad, etc. Last weekend my Father-in-Law and I changed our plugs. Hopefully this thread will help some of you. Note - I went from Denso platinum to Denso iridium (plus wires). He simply replaced his Denso Iridium with the same.
Mike made notes - here they are: I removed 8 NGK iridium spark plugs, four are shown. These plugs have been in the car since new and have 120,000 miles on them. Used spark plug condition is a great indicator of cylinder condition and combustion efficiency. The tan coating on the center porcelain shows a perfect burn in a good condition cylinder. ( I have always used Mobil 1 oil, a high quality oil filter and K&N air filter which helps keep the plugs in a good environment.) Note the new plug in the center is close to old plugs in cleanliness, etc. All used plugs had a 0.040" gap. The new Denso iridium plugs were factory gaped at 0.042" After 120,000 miles on these plugs I thought it was time to change them. After seeing their condition I am sure I could go another 50,000 miles. Since I have changed, cleaned and regapped spark plugs for 40 years (my cars,) I was very impressed with the life and condition of these slugs. In past years I was doing good to get 15-20k miles on a set. Also the Lexus manual specifies either NGK or Denso iridium spark plugs. I am sure anyone would be happy with either brand properly applied. I do notice improved responsiveness with the new plugs.
Note these 14mm plugs are torqued at 20lbs with clean threads and no lube on the threads per the manufacture specifications.
Pic one:
Mike made notes - here they are: I removed 8 NGK iridium spark plugs, four are shown. These plugs have been in the car since new and have 120,000 miles on them. Used spark plug condition is a great indicator of cylinder condition and combustion efficiency. The tan coating on the center porcelain shows a perfect burn in a good condition cylinder. ( I have always used Mobil 1 oil, a high quality oil filter and K&N air filter which helps keep the plugs in a good environment.) Note the new plug in the center is close to old plugs in cleanliness, etc. All used plugs had a 0.040" gap. The new Denso iridium plugs were factory gaped at 0.042" After 120,000 miles on these plugs I thought it was time to change them. After seeing their condition I am sure I could go another 50,000 miles. Since I have changed, cleaned and regapped spark plugs for 40 years (my cars,) I was very impressed with the life and condition of these slugs. In past years I was doing good to get 15-20k miles on a set. Also the Lexus manual specifies either NGK or Denso iridium spark plugs. I am sure anyone would be happy with either brand properly applied. I do notice improved responsiveness with the new plugs.
Note these 14mm plugs are torqued at 20lbs with clean threads and no lube on the threads per the manufacture specifications.
Pic one:
#3
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They really are clean , i can't tell if the flash is whiting out the burn or if it is slightly too lean. Still it is very complete combustion.
Notice those brown rings on the threads , that is where the plugs are grounding efficiently so it darkens more from heat. A perfect ground will have a very even brown tone which is rare.
Notice those brown rings on the threads , that is where the plugs are grounding efficiently so it darkens more from heat. A perfect ground will have a very even brown tone which is rare.
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I just switched over to iridium plugs from platinum plugs I put 102,000 on the platinum and they looked the same as your iridium nice and brown to a gray color and clean. I got the iridium plugs from a friend who sold his car and he gave them to me today I got 25mpg on my 91 lexus using the new iridium plugs and I also use mobil one extended and the K&N air filter I also put the mobil one transmission fluid in the trans and power steering and rear end I don't know if it helps getter better mileage. I have 203,000 miles on the speedo and I even have the orginal hoses air condition pump and radiator I was told by an radiator expert to use the toyota red anti freeze and distilled water and I have for more than 9 years and so far no problems with the car. I did the same thing on a 1986 cressida and got 429,000 miles on everything and it is still on the road I am going to push the iridium plugs to about 100,000 miles plus.
Last edited by Bill Dowd; 05-06-08 at 07:06 PM.
#7
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Wow that is good to hear - the longevity is amazing on your Cresida. I should be good until 300,000+ miles with these iridium. My platinum Denso's were slightly worse (in condition) than my Father-in-Law's but for over 210,000 miles they were exceptionally clean.
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NGK platinum is actually what came installed maybe in pre 98 vehicles. When I changed mine on my 95 the first time they were NGK. Also, my Father-in-Law took out his and they were Denso iridium from the factory!
Regarding the wires I installed Denso first time fit and they were a no brainer - fit exactly like OEM.
Regarding the wires I installed Denso first time fit and they were a no brainer - fit exactly like OEM.
#11
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Dandy job on the plug photos! It is nice to know what they look like after 100,000 miles from a well maintained LS 400.
I hear, from this forum I think, that it is a hellish job to remove and replace a couple of them (at least awkward, for sure). What is your feeling about it?
I hear, from this forum I think, that it is a hellish job to remove and replace a couple of them (at least awkward, for sure). What is your feeling about it?
#12
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Sorry for the late post. Changing them really was not hard at all. You must be careful removing the air box assemble as there are tow vacuum lines. I broke one but repaired it easily. Changing the plugs on the engine was not hard and took an hour or so. You need a torque wrench to set at 18 PSI and a long extension to get the plugs out. As long as tools are available it is quite easy.
When I had my timing belt changed they wanted $180 or so to replace plugs.
When I had my timing belt changed they wanted $180 or so to replace plugs.
#15
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Ha ha LOL you got me on that one - lb-ft is definitely what I meant - had a long week D Also filled up after one full week on the new plugs and tank average was 25.7 MPG. It is slightly higher than what I normally average.
Last edited by steveski; 05-10-08 at 02:26 PM.