High RPMs

Tiny
WYDADC
  • MEMBER
  • 1994 LEXUS ES 300
Engine Performance problem Engine Size unknown Wheel Drive Type unknown Automatic 194000 miles

When I start the car it goes to around 2000 rpms and as it warms it goes down to 1000. Now when I start the car it does the same thing but when I accelerate to 40, 50, 60 or 65 the rpms go all the way to almost 4000 rpms. It hasnt always done that but is that normal and if not what's my problem and how do I get it fixed
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Friday, March 28th, 2008 AT 6:09 AM

4 Replies

Tiny
JACK42
  • MEMBER
The rpm's being hogh at speed sounds like the trans either isnt shifting to teh next gear or is slipping. The idle being too high could be caused by a vacuum leak. Spray around the engine intake area with carb cleaner, if the idle changes, you found a leak
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Friday, March 28th, 2008 AT 10:51 AM
Tiny
RASMATAZ
  • MEMBER
Idle problems can usually be traced to an air or vacuum leak, or in some cases, a faulty idle air bypass control motor or plugged idle bypass circuit. Leaks allow "unmetered" air into the engine and lean out the fuel mixture. The computer compensates by richening the mixture and closing off the idle bypass circuit. One of the symptoms of a vacuum leak, therefore, is a bypass motor run completely shut.

Too fast an idle speed. If an engine without computerized idle speed control is idling too fast and refuses to come down to a normal idle speed despite your best efforts to back off the carburetor idle speed screw or air bypass adjustment screw (fuel injection), air is getting past the throttle somewhere. Common leak paths include the carburetor and throttle body gaskets, carburetor insulator spacers, intake manifold gaskets, and of course, any of the engine's vacuum fittings, hoses and accessories. It is even possible that leaky O-rings around the fuel injectors are allowing air to leak past the seals. Another overlooked item can be a worn throttle shaft
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Friday, March 28th, 2008 AT 2:14 PM
Tiny
SXYCLUV@YAHOO.COM
  • MEMBER
Help I have a problem with my 1994 Lexus Ls400. So I start it up runs fine then I hear rattling. Hesitates when I step on the gas nothing hesitates, then it speeds up so very high like it has a mind of its own. When ignition coil gets overheated it cuts off mechanics help
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Monday, August 21st, 2017 AT 8:21 PM
Tiny
KEN
  • ADMIN
It sounds like the crankshaft angle sensor is going bad and the IAC valve needs to be serviced.

Here are a couple guides to show you what you are in for when changing and cleaning to get the car fixed.

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

and

https://www.2carpros.com/articles/throttle-actuator-service

I would also run the codes to see what come up.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Here is how it is done in your car (below)

Please let us know what happens.

Cheers, Ken
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Tuesday, August 22nd, 2017 AT 3:15 PM

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