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Help Wanted: Spark Plug Turn Brown And White


LexusTom
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So, I feel that my Rx300, Year 2000 should get more mileage than now. The car ran reasonably smooth but the mileage is really bad in the first 10 mins after a cold start.

http://us.lexusownersclub.com/forums/index...&cmd=si&img=604

gallery_11573_95_1111358602.jpg

I replaced the new spark plugs about 9 months ago. Driven about 8000 mile on the new plugs. It looks brownish and white. Like the old one I replace.

It doesn't seem normal, is it? What can be the cause?

Oxygen sensor? A bad wire with one of the cylinda?

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What type of gas mileage are you getting? I had an 01 & was getting between 15-21 mpg. If the spark plugs are a tannish color that's normal. If it's black then it's running too rich, or it's white then it's running too lean. When the 02 sensors go out the check engine light should come on. Hope this helps

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What type of gas mileage are you getting?  I had an 01 & was getting between 15-21 mpg.  If the spark plugs are a tannish color that's normal.  If it's black then it's running too rich, or it's white then it's running too lean.  When the 02 sensors go out the check engine light should come on. Hope this helps

I got about 15-16 for mostly local. The actual (calculate from the fuel pump) is usually about 1 mile less...

But, if I drove a long trip, the mileage get much better after 20-30 mins. For example, if I reset the computer after drove 30 mins, the computer shows 23, 24 on highway.

But, if the car had been only run for 10 mins, it shows about 20 on highway. I suppose the car doesn't take that long to warm up. Cus, many of my trip is less than 10 mins...

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If most of your trips are 10 mins or less then 15-16 mpg is normal. You need to monitor the gas mileage the next 2-3 tanks & take any average. Keep mind also that now that the weather is colder especially in the morning it takes longer for the engine to warm up. Also in the Bay Area gas stations are still selling winter blend gas which reduces gas mileage. You should see an improvement after the weather gets warmer & when they switch out of winter blend gas.

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If most of your trips are 10 mins or less then 15-16 mpg is normal.  You need to monitor the gas mileage the next 2-3 tanks & take any average. Keep mind also that now that the weather is colder especially in the morning it takes longer for the engine to warm up. Also in the Bay Area gas stations are still selling winter blend gas which reduces gas mileage.  You should see an improvement after the weather gets warmer & when they switch out of winter blend gas.

Cruz, your info is helpful. I feel a bit relieved.

Ha ha. I used to live in bay area, but moved to Seattle last summer. :-P

But, I suppose they might keep the winter blend even longer here... need to update my profile...

I think my spark plug has some carbon disposit. Can you take a look at my picture? It was a picture of my spark plug this morning. The tip of the plug looked a bit white. The side looked brown, and the base looked black...

A friend of mind told me that I might tighten the plug too much. He think it looked like the plug run too hot.

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LexusTom,

You really need to put the correct plugs back in your car. The Iridiums are the finest plugs out there and last forever--I think you will notice an improvement in both idle and highway mileage.

How many miles were on your car when you pulled the original plugs?

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LexusTom,

You really need to put the correct plugs back in your car.  The Iridiums are the finest plugs out there and last forever--I think you will notice an improvement in both idle and highway mileage.

How many miles were on your car when you pulled the original plugs?

Ok. It seems to be the consensus. I will do it then. Maybe report again in a few month.

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