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Iridium Plugs


brucelee
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I changed to Iridium Plugs a couple of months ago and I have become more and more impressed with the Lexus engineering every time I work on the car. There is a very systematic way to perform each task and you do not have to remove every component in site to do it as I've noticed in other engine compartments.

This weekend, I replaced the Distributor Caps and Rotor Buttons. The Driver side is much easier as with the plugs, but after studying the passenger side for a little while, I discovered that there is also a systematic way to get to the Distributor. The only difference to the Driver side is remove the top radiator hose, unload the accessory belt tensioner and remove the top belt from the pulley and four vacuum hoses. You also have to remove the air inlet from the air filter box to the Intake. If someone needs it, I can give detailed instructions as to how these components are removed.

And yes, there is a noticeable improvement to how quick it starts up and it seems a little quicker revving.

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well i was told that iridium plugs are very fuel sensitive (bad quality of fuel will destroy em).? I dont know maybe it depends on car and other staff also but people I talked told that they change those plugs every year...

tom

sc400

Based on the properties of iridium, the opposite would appear to be true. They are reported to be able to go 250K miles between changes.

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The life expectancy for the Iridium plugs are highly influenced by the condition of your engine. Check the condition of the plugs that you remove. There are numerous places on the net that you can see a plug condition chart. Compare your existing plugs to this chart to determine if there are any conditions that will affect to longevity of your plugs. If the plugs are dry with a slight off white petina to them and no oil residue, then the engine condition and ignition system are in very good condition. If there is oil buildup on the plugs, then the iridium plugs will be short lived.

The beauty of the Lexus engines (SC 300 & 400) is that they are the product of exceptional engineering. My SC400 (93) has 182,000 miles and the compression test was within 96% of new specification and the plugs looked great.

I've been going throught external components and replaceing them, such as coil, plug wires, ditributor caps and rotor buttons, hoses, belts, air filter, fuel filter, etc. These components are more susceptible to failure than the internal components. The only internal engine component that I will replace this Summer is the rear main seal. This will run approximately $400.00 to replace (Not Lexus Service).

Preventative Maintenance is the best maintenance. Replace it as you see fit instead of replace it when it fails, some failures could be catastrophic.

Good Luck!

:cheers:

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My SC400 (93) has 182,000 miles and the compression test was within 96% of new specification and the plugs looked great.

Now that is impressive.

I have the Denso Iridiums (IK20 if I remember) in my SC4...didn't notice a difference, but then again the oe Platinums are of a good design and there was not a 'need' for a better plug like there would be in a FI car. I use NGK 6097's for that.

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Hey Jon, do you have the info on plugs recommended for the stock compression turbo cars. I think Scott in Cincy was running 3330's at .32 but I don't remember exactly. Do the 6097's hold up better or what? I'm going in there shortly. Need to get gaskets, belts and ignition stuffs.

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AWJ, the 3330's are more commonly used, but if you look at the 6097 it's closer to what Toyota meant to be used in there, but copper. Here's the specs on the 6097 aka BKR7E - heat range 7, V-grooved 1.5mm dia electrode, .0315 pregap.

I don't have enough time on them to give you a critique' AJ, we went thru three sets of plugs just in tuning before we even pulled it out of the shop, wanted to make sure they were clean and also wanted to keep monitoring them, but not fun when you have to yank the t-body every time.

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The life expectancy for the Iridium plugs are highly influenced by the condition of your engine. Check the condition of the plugs that you remove. There are numerous places on the net that you can see a plug condition chart. Compare your existing plugs to this chart to determine if there are any conditions that will affect to longevity of your plugs. If the plugs are dry with a slight off white petina to them and no oil residue, then the engine condition and ignition system are in very good condition. If there is oil buildup on the plugs, then the iridium plugs will be short lived.

The beauty of the Lexus engines (SC 300 & 400) is that they are the product of exceptional engineering. My SC400 (93) has 182,000 miles and the compression test was within 96% of new specification and the plugs looked great.

I've been going throught external components and replaceing them, such as coil, plug wires, ditributor caps and rotor buttons, hoses, belts, air filter, fuel filter, etc. These components are more susceptible to failure than the internal components. The only internal engine component that I will replace this Summer is the rear main seal. This will run approximately $400.00 to replace (Not Lexus Service).

Preventative Maintenance is the best maintenance. Replace it as you see fit instead of replace it when it fails, some failures could be catastrophic.

Good Luck!

:cheers:

Last summer i threw in the Iridiums. My old plugs were filled with oil and residue. And just recently I noticed my engine has been running not so good. My RPM meter goes down than usual. Engine just dies when I have my sound system up when i'm at a stop light. Transmission shakes a bit when I go around 30-40 mph. Are these signs of a bad Iridium spark plug?? If so, which plugs do you guys recommend?? Thanks.

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by the least, sounds like you need a new alternator hershy. your rpm idling low can be adjusted, look for the throttle cable and theres an electronic one that you can adjust which is right in front of the intake manifold. but i do not think that is the cause of bad plugs...bad plugs just gives you poor performance. well good luck buddy.

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:(

I'm afraid you have more problems than just bad plugs. If your old plugs had oil residue, you may consider have a compression test done. It sounds as if you have excessive ring, cylinder or piston wear. There should be no oil on your plugs. Black dull carbon is another issue, but wet oil is not good.

It's better to find it now than after the engine lets loose.

:whistles:

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you can bring it to a mechanic who will charge you an arm and a leg, or you can go to autozone, kragen, etc and rent something called the "compression test/er" which runs only 6 bucks. make sure you ask them if it comes with everything you need.

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A compression test is fairly easy to do. The tough part is removing the covers to get to the Spark Plugs if you have not done this before. The other thing that you must do is use a remote starter attached to your starter so that the vehicle does not start when you are turning it over and it also prevents the fuel system from injecting fuel into the cylinders while doing the test.

:cheers:

It may also be a good time to do a leak down test at the same time.

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