Ok so this is the first saturn ever owned in my family so i have noone to help with this. about three months ago i bought a 1999 sl2 with about 185k miles and it was running great besides a quart of oil being burn every thousand miles. but for some reason it idles really high when i start it the engine jumps to two grand then gos to 1200. but even after it warms up it never gos below 900 rpms. i dont know if this is normal? but just lately it through a po404 code and there was another one but i cant recall it. i change the plugs and the other code has not come back. but the po404 im told is the egr value. will this improve my gas mileage? and one more thing some times when i put it in park or neutral it will jump to 3000 rpms for no reason i thought it might be a sticky pedel but nope. if i shut the car off and restart its fine. and if i drive it when it dose this it will go on its own it gets up to like 30 with out me even touching the gas.
but any answers to my questions would be greatly appreciated.

 

I would try replacing the throttle position sensor for the high idle problem also Take off your air cleaner tube and inspect the Throtlle plate for carbon build up If there is a lot of build up clean it with a tooth brush and carb cleaner the other posibility is that you have a large vacume leak somewhere and the computer is compensating for that by raising the idle As far as the egr Vavle is concerned you need to replace that with a new one dont think this would be causing the idle isue. I have a 2002 sl2 auto trans and avrage about 28 miles a gallon.

One more posibilty is the idle air control vavle

 

ok thanks ill try that for the high idle problem. but some times i get about 21miles to the gallon. but it only has the code every once in awhile its not like it keeps coming on. and then some time it gets about 33.

i was wondering if it could be the gas gauge becuase i found that i can drive for about 50 mile well on E and it never ran out of gas.

 

You don't check gas mileage by the gas gauge, you divide gallons into miles driven.

High idle: clean throttlebody inside and out, and yes check for a vacuum leak

 

Hello,
If you stand by the tailpipe do you hear it miss firing? If so the intake gastket need to be replaced, It will idle higher, and cause your mpg to go down. It may cause the check engine light to come on. due to a miss fire code. It will take to about 2 hours to fix.

 

that's good and fine but misfires can be caused by many things -- and he never said he has one (??) and P0404 is not a misfire code anyway

if you're idling at 900 indeed you likely have a vac leak and a dirty throttle body.

 

Derf, i have had the last six Saturns SL1 have all had bad intake gaskets on number 1 cyl, why did't saturn add another bolt, Very bad design on there part.

Phillyboy, take a can of brake cleaner and spray it around the intake gasket and if the engine just about dies then you need to replace the intake gasket.

 

and I've had 11 S-Cars and not one of them had a bad intake gasket.

 

For the record I think a bad intake gasket qualifies as a vacuum leak on the intake, so at least we are all talking about the same type of issue (except the non-confirmed misfire).

Also for the record, the SOHCs did have an issue with bad intake gaskets for a few years there...however this is a DOHC and I don't remember any similar issues plaguing these....

I have a 95 and 97 DOHC and no bad intake gaskets here

And don't use brake cleaner -- that stuff is nasty and not designed for under the hood diagnosis (it's for brake parts and burns skin) -- use throttle body cleaner on a VERY COOL running engine-- and you might as well check around the throttle body gasket and things running to the throttle body (line from PCV, at map sensor, while you're at it too...if the idle drops, you've found the leak.

 

i forgot to talk about that misfire. but it only happens sometimes when im driving for some reason. but thanks for all the information i am going to check it out tomorrow now that i final have a day off work.