What are the symptoms of a vacuum leak?

[Arauz]

Well, I'm just wondering cause my idle rpms moves slightly up and down and my whole exhaust is sounding pretty muffled compared to a week ago. Car rides different but i just can't put a dot on it. How can I fix this? Thanks Sfld

 

[m4nfred]

idle surge...

 

[McWire300zx]

idle issues, bad gas mileage, high pitch whistle emitting from source of leak, hesitation..

 

[JTNismo]

I have to insist you at least try the following if you have a KAde. Not sure what other cars this may work on, but I tried it yesterday and it worked like a charm for me. Of course let me not forget to recognize credits for this advise to Aero-ks13.4. Thanks again broe!!

Everytime I have set my timing it is done wit the TPS unplugged. You are really supposed to make sure that the idle speed is around 800 when setting the timing. You can adjust the idle screw if necessary. There have been people who cannot lower the idle speed enough with the screw. You cannot set the base timing with the idle speed high.

On a side note

**Mostly the main cause of the idle issue is a dirty IAC valve.**

It's tucked under the intake manifold near the fire wall. Very hard to get at and expensive if you take it to a shop to get it fixed. But it doesn't need to be replaced, you can fix your nasty idle issues for less then $10! Here's how...

Get a bottle of Intake cleaner, not carb cleaner, intake cleaner.

See this hose:

The bigger one on the right goes from your intake to the IAC valve. If you pull it off while your car is running it will die after a second or two. When your car is off, pull the hose off but leave it still on the nipple enough to seal. Go start your car and then come and using one hand pull the hose off and with the other hand keep your idle up by opening the throttle. With your now free hand get the bottle of intake cleaner and spray some of it into the IAC tube. The car will stumble but make sure to keep it from dieing or you will have to put the tube back on and start the process all over again. Repeat this process several times,use about half the can. Re-install the tube and take the car for a drive! I drive for about 20 minutes and everything should fine.Do this and you should have no idle problems.