[Herr]

Earlier today I took a drive in my aunt's 09 Suzuki Swift. She been driving it for around 6 months or so and has covered 73000km.

When the car is at a complete standstill the RPM usually is around the 700 mark but it sometimes falls to around 400-500 and gives the sensation as if it is going to stall before it spikes up again between 900-1100 and then gets back to it's usual 700-750 range.

Happens regardless of whether the car is in P, R, N or D. Doesn't change either if the HVAC is switched on or off or if any of the auxiliaries are switched on or not.

She did say it started happening around 2 months ago and one thing she did notice after that started to happen the fuel consumption went from 6.5l/100km to now around 8l/100km...

Any ideas what could be causing it, car had a regular service a few weeks ago, cleaned the throttle body, new spark plugs and new fuel filter.

[CurlyBen]

I'd be looking at the idle air control valve first, sounds like it could be sticking. Check for disconnected pipes/hoses/wires. Could be MAF/MAP.

[gbduo]

Yeh IACV would be my first bet. They normally require a good clean and are a right PITA to get off the inlet manifold. Whilst you are there though, you may as well clean the MAP sensor by removing it and dousing it in brake fluid/cleaner to remove the carbon deposits.

I guess you could try taking the inlet pipe off and using an atomiser to throw redex into the intake whilst the engine is running on a high idle to see if that will sort it?

Also, it if it is a cable throttle, check the amount of play in the end or tension, should be no more than half inch in either direction.

[JC.]

Good hard drive and some carb cleaner down the throttle body would be a good start.
Elderly folk often have cars that are totally coked up.

When I started using my grandads jag it took nearly 2 weeks for the kickdown function to start working again!

[stevoboy]

(Original post by Herr)
Any ideas what could be causing it, car had a regular service a few weeks ago, cleaned the throttle body, new spark plugs and new fuel filter.

Could also be an air leak into the manifold somewhere downstream of the throttle, which confuses the ECU as you are effectively getting a bit of extra air that the MAF does not see. Also check vacuum hoses / crankcase vent pipes etc which are hooked up to the manifold. On the off chance you have access to diagnostic kit you could check the ECU fuelling adaptions to see if it is doing significant fuelling corrections which might indicate a leak.

[M4LLY]

Engine Management problem?