High idling goes normal when clutch is pressed.

[jarod]

Hi Eric, I’m one of your fans from the Far East part of the world. I drive a Mazda 323 (aka Protege) 1.6 B6 DOHC engine with M/T.

My car runs great and after a recent vacation the car suddenly does idle high – between 1200 and 1500. Checked air hoses but everything seems to be ok. Then last night something funny happened. As I was sitting at a light with the high idle, I pushed down on the clutch pedal and Immediately the RPM dropped down to normal at 800. Released the clutch and it went back up to 1200.

I know most would would say that pressing the clutch would help your low idling engine to raise the RPM but mine’s totally the opposite.

Any idea perhaps? Thanks in advance.

Topic

[dreamer2355]

First off, welcome to the forums!

So basically in gear, depressing the clutch drops the idle where as in neutral without using the clutch the idle is high?

Am i understanding you correctly?

[ytram]

Sounds crazy but, my mom has a 96 or 97 Saturn that was doing the same thing. It is well known for the ECT (engine coolant temp) to do some funky things on the Saturn. ECT was changed, and a few possible leaks in the emission system was taken care of and now works like it should.

[EricTheCarGuy]

That is a strange problem indeed and the biggest stumbling block is the way the idle changes when the clutch is depressed. Just for the heck of it have a buddy depress the clutch pedal while you watch the crank pulley on the front of the engine, if you see it move when the clutch is depressed then you probably have issue with the thrust bearings in the engine, these sometimes have a problem on manual trans cars because they suffer a lot of load stress when the clutch is depressed.

As for the idle issue if you ARE having issues with the thrust bearings this could explain why the idle drops as you depress the clutch however to diagnose the idle problem you’ll have to go the traditional rout and start by first checking for vacuum leaks as well as the operation of the idle air control valve.

[Author]

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