Car idles low.

[Jay Zarcadius]

i just got the car today, its a 1991 NON turbo and it idle's at like 400-450 RPM and occasionally it just dies because it wont keep it going. if i give it a little gas so it sets at about 900 it holds perfect. i've established it could be a number of problems from a loose cable to a bad throttlebody, but i was wondering if anyone has had this problem and might know what to try first.

 

[ove_98 TSI]

have you adjusted the idle screw on the throttlebody

 

[mike hobbs]

does the car run like crap or is it just the idle? cause if so yea i would mess with the idle screw.

 

[92spoolin']

Check all your vacuum lines as well but I would adjust the idle screw as well before you do anything its the easiest to start with.

 

[Daaan]

definatly try adjusting the idle screw. set it so it idles at 900RPM

 

[BOC Jason]

BISS screw. http://www.vfaq.com/index-main.html

 

[Jay Zarcadius]

thanks guys, i'll try in the morning. i didnt think about an idle screw, dont know where exactly it is though. havent gotten a repair manual for the car yet, i will be soon. i did think of a vacuum leak but that was just tonight i thought of it. yes the only issue is the idle, if i hit the gas to hold it around 800 or so then the engine is fine, but when i let off of it the engine falls back to about 400 and starts vibrating because its too low. occasionally it will just stall out while i drive it when i put the clutch in. i'll check on it tomorrow and update with what's worked / not worked.

 

[BOC Jason]

the link i sent you includes some pictures of where the screw is located on the Throttle Body it's self. Also here's a great website that gives a virtual layout of the engine. I should definitely help.


Virtual Tour of the DSM Engine Bay - Quadrant map

Here's the link your going to want...The BISS screw is circled in purple. Hope it helped

http://members.shaw.ca/dsm.1000q/Engineprimer/2G/throttlebody.htm

 

[Jay Zarcadius]

actually someone i know who works for chrysler told me not to touch that because it'll throw off the ECM. wouldn't doubt it because the engine light is coming on sometimes but when i tried to get the code there wasn't one stored... it's confusing the heck out of me with all the things it could be but i dont know how to figure out which one it actually is...

 

[BOC Jason]

The first thing you want to do for sure is a Boost Leak Test. It can't hurt (as long as you do it right ) and it's just a simple insurance.
After that you're going to want to narrow it down to the most likely source of the problem and try from there.

 

[Jay Zarcadius]

as i said in the first post...i have a 1991 with NO turbo so i don't have any boost to leak.... so since thats out i'm back to thinking it's the speed sensor / reed switch. the engine light does come on -sometimes- but when i try to check the code it doesnt give me one, it gives me the "normal operation" code. there is a code for the speed sensor though, code 24, and i've read several troubleshooting things online through here that say it will give my symptoms, but there are other things it could be. i also have no clue how to go about finding, finding a replacment, and changing said sensor either... the articles diagnose the problem but don't explain how to correct it. if anyone could help me out that'd be great.