High RPM at idle

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John16
Posts: 67
Joined: Sat May 28, 2022 3:05 am
Car: 1993 Nissan 240SX hatchback

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Can someone point all the places to look for High RPM's at idle? Mines wont go under 1300. These are the things I havchecked but not for sure im doing it right.

1-Distributor: Timing at "20" and Distro "pointing at it"
2-Idle Screw close to the wall where my EGR used to be (eliminated)
3-TPS? Should I change it? I play around it it and it just makes little difference.
What else will have to do with this? and bring down the rpm at idle for this sucker?

:wtf2: :werd: :gotme


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PapaSmurf2k3
Site Admin
Posts: 24000
Joined: Thu Nov 21, 2002 3:20 pm
Car: 2017 Corvette, 2018 Focus ST, 1993 240sx truck KA Turbo.
Location: Merrimack, NH

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If the idle screw doesn't get her, you very well could have a big ol vacuum leak. I've used a cigarette to "smoke trail" show me where one might be, but be careful you don't burn a line while you're poking around in there.
You can also spray some starting fluid or other combustable fuel in general areas to see if the engine idles up. If it does, you know you're close.

John16
Posts: 67
Joined: Sat May 28, 2022 3:05 am
Car: 1993 Nissan 240SX hatchback

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The idle csrew works but not as much as it should. I mean I still can get my rpm under 11 minimum with the AC on and thats ok but once A/C is off it stays up to 11. I did a smoke test one time with a smoke machine attaching it to the Brake Booster line and engine on and never saw any smoke leak. Do you know any other place to hook up a smoke machine and check for leaks.

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PapaSmurf2k3
Site Admin
Posts: 24000
Joined: Thu Nov 21, 2002 3:20 pm
Car: 2017 Corvette, 2018 Focus ST, 1993 240sx truck KA Turbo.
Location: Merrimack, NH

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If you're using a smoke machine, you don't really "hook it up" to anything with the engine running... you just wave it around the engine bay like you're some kind of catholic priest and look for the smoke to be getting sucked in to the engine at any place.

If the smoke machine is able to achieve positive pressure, then you could hook it up to one of the vacuum lines with the engine off to see if smoke is coming out from anywhere. Note- your brake booster line should have an in-line check valve, so you'll want to be on the correct side of that (the engine side) if you hook up a positive pressure smoker.


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