today i found out my alternator is shot and i am currently ordering a new one. was wondering if this could somehow be related to the high idiling and trouble shutting off car

for a while the car would randomly idle high. sometimes while i am at a light and i would not be able to shift into gear without lowering rpm's so i would turn car off that would drop the idle allowing me to put it in gear and i would restart the engine once in gear note the car didn't shut completely off during this process maybe this could have affected something?

any suggestions would be a big help

Going to need more info is it a carbed car.

thanks for your reply yes it is a carbed car 4 barrel

Please provide year, make and Model of car along with the engine and any other specifics you can think of.

1986 z28 chevy camaro

M5,A4 LG4 V8 9.5:1 5.0 (305) 165@4400 250@2000 4bbl

LOL, did you get that out of the book? hehe

High idle is often related in some way to a vacuum leak. Does it do it if you are at idle or only after you've driven it a bit?

If it does it at idle, I'd check all of your vacuum lines to make sure all of them are seated properly and none have any holes in them. After years they can go bad or get hard/brittle and not seal properly. Start by blocking off all of the ports on your carb and intake and see if your high idle goes away. If it does, hook them up one at a time and see where it goes crazy.

it would do it randomly and then i havn't been driving for a while because the car kept dying on me turns out i have bad alternator 2.5 volts so maybe when the car was idling high that was the alternator going bad if problem continues after i will check vacuum lines do you know of any sites that have schematics for that or explains the way it works thanks


i got those numbers from this site gotta say not so happy the car only has 165hp but now just trying to get it going again engine swap might be in my future along with some body work haha need a garage first

For the car, remember they were built in the time of gas-miserness and 165hp was good for the time.

You can do a search on the site here for the vacuum diagrams.

For the alternator, it would cause problems in the electrical, andwhen your battery got weaker you'd have problems keeping it running. But I don't think it would cause your high idle issues.

yea the other two z28 models that year had 190 hp but i bought it 10 years ago before i knew about all the different models i will do some research on the vacuum system thanks

Heres what im thinking. You might wonder how a car can continue to run after the ignition is killed. I mean really it dosnt make sence at a glance no spark how does it burn? Well I'll tell you how. Its almost working like a desel motor at that point. Your cylinders have a lot of heat built up from something like a lean mixture or advanced timing enough so that as the fuel is compressed it will ignite itself. Figure out why things are running so hot and youll find your answer. Check your timing vacuum leaks (or anything else that would cause u to run lean). Any check engine light? Might be a good idea to get the charging system fixed first though.

Yes the high idle alone will make the motor run for a few seconds after you shut it off. My car idles at about 900 with 16 degress of timing if i run it up to 1500rpm the timing will be higher so that in turn would make the car keep running when i shut it off.

thanks rolling thunder, and 84 yea waiting on the alternator to come in then i will check the vacuum system for leaks

OK well if you find no vaccum leaks and it always idles that high then do some adjusting on the carb (idle screw) but if its hit or miss you got something going on. And dont for get to check carb gasket easyest way is to get some starting fluid and spray a little around the bottom of the carb not to much and just listen for change in idle.

thanks will do
here is a side question what is the whole point to the vacuum system? can it be removed?

No, you cannot remove it. The engine is basically an air pump, sucking air in and blowing it out (Intake and exhaust). The vacuum that the engine generates while running runs things like your brakes and HVAC (Runs the doors when you switch between vent and defrost). On some models it can deal with the tranmission or cruise control, and emissions. So it's pretty important.

Oh ok thats a bummer I thought it was just an emmisions thing. Ohwell

just an update i changed out the alternator and the idle went back down to normal

car still continues to run after key is removed but it does want to die down but it just seems like there is something trying to keep it join i guess its still getting spark should i change out ignition switch