Fluctuating Idle issue

dude, the year and the miles?

sorry, 1998 approx 180 000 km

Surging is caused by a sensor getting confused by an unusual condition is can not deal with and thus dumps fuel to try and compensate. Caused by vac leak, intake manifold leak, air in the cooling system, etc.

Thanks for the tips, is there a sure way to test what might exactly be the issue??? Could it be that the throttle body needs cleaning?

Start with the simple ones of air in the cooling system and a vacuum leak on the engine. Check the vac hoses for a leak.

Did some basic troubleshooting, found that when and only when I have the defrost cycle on I get the surging, could it be the AC?

Isn't the A/C a switch away from being turned off. Is so, turn off the air and run the defrost. See if that narrows it down.

They are not seperate controls. When I select defrost I can hear the AC turn on. At this time is when the engine surges. If I select panel vents or panel/floor there is no surging only when I select defrost is there a surge.

the ac automatically comes on when I select defrost Appreciate the help.

I am unclear about which way to lead you on this. But I know that the ECU is unclear about the step up it must do to compensate for the pull down caused by the ac kicking in. Can someone else chime in if there is a sensor that is responsible for monitoring the ac?

[quote:850c31f51c="gurmeet"]the ac automatically comes on when I select defrost Appreciate the help.[/quote:850c31f51c]

Hey gru,
Your A/C will come on with defrost setting as its used to "dry" the air that blows on your windshield to remove any condensation faster. As to bruces question, several sensors monitor the A/C HP and LP Switches,also if the ac controller is automatic (electronic) it will control some aspects of the a/c compressor. Hope this helps

Regards,

Chris

Do I have no choice but to take my car to a shop a have a diagnostic check done on it. Is there anything I can do my self?