poor gas mileage

I have a 2001 isuzu rodeo v6, 4x4 auto with 60,000 miles on it. and recently my gas mileage has gone from 18-20, to 13! I have already scaned the ecm,
returning no codes. changed spark plugs, and air filter. I don't really know what to do next. the truck runs great, makeing great power, probably because its stuck in a closed loop sys. anyone have the same problem? what did you do to fix it?
smitty
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smitty wrote:

Around town with AC on 16 city and 18-20 highway is typical. What about wires, cap, rotor etc? Another possibility is a bad O2 sensor causing it to run rich. If it were that bad it would trip a code though.
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Indeed it could be a bad O2 sensor as that will only set the check engine light when it completely fails. Could also be dirty fuel injectors. Either one can cause poor mileage while not affecting performance.

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converters - they have a nasty habit of breaking up and clogging the flow. Any reputable exhaust shop should be able to test it for you and tell you if yours are OK. SOMETHING is different.
Be happy, though - all of us Trooper owners with 3.5 liter engines, besides having to put up with high oil consumption, also tolerate lousy mileage (15-16) unless you have a diesel... and then I don't know what they get but I'm sure it's better. r/ Steve
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GreenGas wrote:

The 3.2L is also known to consume a lot of oil. Both engines gain HP by using short skirt pistons. More power but oil consumption is a trade off.
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The 3.5 in our 2002 doesn't use much oil. It's rather odd, sometimes it will use a half-quart between changes, sometimes it won't. But, it's also only at 26k miles so far... :-) I just changed the oil this weekend and made the change from Havoline 10w30 (since the first oil change a little over 1000 miles) to Mobil 1 Synthetic 10w30. Hopefully it will be worth the price in the long run...we plan to keep this one a loooong time. We joke sometimes that our 5-month old will be complaining about having to drive that "old piece of junk" when he learns to drive...lol...
The 3.2 in our 94 does use probably 1/2 to 1 quart between oil changes on average. (I change it every 3000 miles.) It also has 130k miles on it!
Sometimes I wish I had the diesel in the 2002...we tow our 18' travel trailer with it, I'm betting it would do a bit better than the gas engine...
Wesley

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Isuzu has a known problem wih the engine in reguards to excessive oil consumption. they will REPLACE theENGINE if it is still uder warrenty. unfortunatly, there is a backlog, I am1 of 15 folks getting my engine replaced. never got anything from Isuzu. I have a 2000 LS 4wd Trooper. I had the 90K tuneup ect because I wanted to have the dealer look it over before the factory warrenty expired. I mentioned that I thought there might be an oil leak because I was adding oil every few weeks. they did an oil consumption test. which means you go to the dealer every 500 miles for the next 2k miles. i do not know what the minimum critera was but my trooper was down a quart every thousand miles. the dealer reported it to isuzu, and I get a new engine. I just have to wait my turn, check the oil once a week or so, and soon I will have a new engine. something about short pistons or something. so if you are under warentty, ask for a oil consumption test. if you are out of warenty, CHECK YOUR OIL FREQENTLY, about every 500 miles. 3k miles between checks might be way too long. the engines are about4K plus installation, and all the engines are gong to dealers for warrenty work. they are hard to come by. if you lose an engine, you might be SOL in trying to repair it.
Jp
Wesley wrote:

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