extreamly high idle

[mustangGt87]

my idle is like at 300 and stays there..i have checked everything.what could it be?i have a adjistable fuel preassure regulator..could it need adjustment?im pretty shure its not a vacuum leak.its not the tps.or any thing like that.i need new ideas to check..i dont have a computer tester thing or a test light or a voltomoter..so gimme some ideas please..i just want to drive...thats all..drive..just drive..................because im a kid..and i wanna go fast!yay

 

[v8only]

give us some history, when did this problem first start?

 

[mustangGt87]

it just started.i havent even driven it yet though...i put the engine in from my f250,but i put the engine in the f250 from another car..lol..the engine ran fine in the f250 and the other car, but it was kinda hard to start in those cars.i put on the mustang intake and everything for the mustang and such.and then the preassure regulator and a new cap and rotor and oil and what not and now the first time i started it....it idles at 3000 or more...could it be bad sensors like o2 sensor or temp sensor or any sensor on the car.i know the tps is ok and there are no vac leaks..im not shure though

 

[v8only]

crap, no offense, but you're all over the place. Let's seperate the facts:

1. exactly what originally did this motor come from?

2. speed density or mass air?

3. you can't really verify tps with it idling at 3k

4. have you pulled a vacuum reading? an actual reading, not just guessing you have no leaks

5. Have you tried adjusting base idle?

 

[mustangGt87]

crap, no offense, but you're all over the place. Let's seperate the facts:

1. exactly what originally did this motor come from?

2. speed density or mass air?

3. you can't really verify tps with it idling at 3k

4. have you pulled a vacuum reading? an actual reading, not just guessing you have no leaks

5. Have you tried adjusting base idle?

it came from a non ho mustang.its speed density.i havent done a vacuum reading.ive adjusted the base idle.i can take the screw all the way out and it still idles the same.

 

[v8only]

This may be an odd chance, but on my car I had to hog the holes out on the throttle bracket that mounts to the intake. Because I did that, the bracket sat too far back, causing a very high idle. I had to push the bracket forward and rebolt it.

speed density is EXTREMELY sensitive to vacuum, I'm not sure how accurate of a readng you'll get at 3k, but I'd start there.

in fact, fire up the car and yank off the vacuum lead going to the map sensor on the firewall, what happens when you pull the vacuum from it?

 

[mustangGt87]

lol i cant try that tonight because i have no mufflers.i only wish i lived on the strip.,but ill get up and do that in the morning and then do it.do i plug the sensor vac line or just let it free?

 

[jrichker]

You guys with idle problems could same a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first post has all the fixes, and steps through the how to find and fix you idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.