I have a 98 Saturn SL2 with 230,000 miles. It runs great and gets almost 40 MPG highway. The only problem I have is that the idle speed varies from about 600 to 1700 RPMs as if I were revving the engine with the accelerator.( but I'm not ) Any idea what's causing this?

Great car, 30 MPG, Good for 200,000 miles with regular maintenance, If it has an out of control idle speed it will need new ( IACV ) Idle Air Control Valve. My 2003 Lancer runs like a top.

Do you have a question? Let me guess, you want to know the MPG rating for the car? Easy, the US EPA rates it at 15 mpg city, 24 mpg on the highway. Your mileage may vary.

yea it sounds like someone like most wanna be mechanics take a torques screwdriver and run the idle screw up on the throttle body instead of fixzing the real problem also you may want to concider testing and changeing the TPS

Hi Darlene,

These engines can go well beyond 500,000 miles, and I know several people that can attest to that. There is one important thing you must know. ALWAYS check your oil at every gas fill up! Your SL2 is probably burning oil and needs to be checked. If you let it get too low you will spin bearings in the engine and it will be rendered useless. Check the oil and keep it at the top of the hatchmarks. It's a good idea to get two quarts of oil and leave them in the trunk this way you can fill as you need it.

The idle is probably the Idle Air Control valve (IAC). It is probably dirty and needs to be cleaned. Removing the throttle body and cleaning with carb cleaner to get the carbon off will get your idle working again. You cannot reset idles on these car and DO NOT touch the idle stop, that is not how idle is managed nor adjusted. The idle should be 1,200 RPMs cold and 800-850 warm.

Thanks,
Joe

Go to your local shucks or auto zone and they can check any codes behind your check engine light and it's free. It sounds like one of two things a O2 sensor or your mass airflow sensor but they will tell you for sure

Problem solved by the dealers service department. Thanks

try using gas from a different place octane levels do vary.

EPA mileage figures are estimates, and seldom does it have anything to do with the real world, My new car is rated at 19 city and 28 hiway, it gets 22 MPG max. The only thing you can do is make sure the pressure in the tires is correct and run the recommened oil, keep the car in good running order.

I just went through the same ordeal with my 2002 Saturn SC-1. I don't know if your SL1 has a 1.9 Litre engine, but if it does then maybe my ordeal will help you.
My SC1 was getting great mileage until it started idling above 2,000 RPM. I'm curious if you are still getting 38 mpg because my gas mileage went down the toilet!
Initially I thought my problem was electrical, so I changed all the plug wires and changed out no 1/4 coil because my code reader said I was getting a misfire on No. 1 and 4 cylinder. That didn't change so I replaced the the Ignition Module, still high idle. Then I replaced the Idle Air Control Valve; still no change. Next I pulled off all the fuel injectors and sent them to Witchhunt to have them cleaned. Still no change. Still idling at 2,000 to 3,000 RPM. I happened to read on the Saturn Forum Website that if an Intake Manifold Gasket is faulty, just spray some brake cleaner on the backside of the motor and if it stumbles, there's your problem. If you've eliminated all the possible variables than that had to be the problem. I changed the gasket and it runs great! I'm back to 38-40 MPG and I idle at 700 RPM. I would try the Brake Cleaner on the backside of the engine and see if it stumbles. If it still does, then your mechanic didn't do a good job or you can easter egg like I did!

How many miles do you have on this engine, and when is the last time you changed your oil? You might want to add some Rislone to your oil and that will get rid of some of the carbon build up after your next oil change.

Compare Fuel Estimates for 2006 Mitsubishi Raider Trucks Here's a comparison of EPA fuel economy ratings among the trucks in the 2006 Mitsubishi Raider lineup. As always, your mileage will very likely differ. 2006 Mitsubishi Raider 2WD 6-cylinder Trucks * 3.7L, 6-speed manual, 16 city / 22 highway * 3.7L, 4-speed automatic, 16 city / 22 highway * 3.7L, 6-speed manual, 16 city / 20 highway