Hi guys.. My car has an idle problem..

[raihan_rahman03]

Hi all,

When I'm at the stopped lights, my car idles very poorly and the rpm often drops to 300. If it drops below 300rpm the revs kind of bounce to 800 and back to down to 300 every second. The car has also stalled on me about 5 times in the last month.

I took it to Mitsubishi Pennant Hills and they replaced the fuel filter, cleaned the injectors, flushed the fuel tank, performed a carbon cleaning service, changed the spark plugs and cleaned the intake. $975 later my car still has the exact same problem.

My lancer is a 2.4l CVT auto. 120000 kms on the clock.

Any help would be greatly appreciated. Also if you guys know of a good mechanic in Sydney, PLEASE LET ME KNOW!!!

Many thanks in advance..

Ray

[Lancer1993]

Sounds electrical to me, maybe the ECU. Did they plug the car in a run a diagnostic on the computers?

Sometimes its not the engine but the CVT, a nephew has a Pulsar with one and it started stalling, they ended up replacing the CVT but that was under warranty.

Does this happen only when in gear or also when in Park?

[aspir3]

It could be anything. Just check for obvious things like loose vacuum hoses and spark plug leads

[raihan_rahman03]

Hi Lancer1993 and aspir3,

I hope its not the ECU or even worse the CVT. The Idle is rough on Park and the revs do bounce on idle whilst in Neutral. I had the diagnostics checked at an independent mechanic today. One of the oxygen sensors is all over the place and bouncing from top to bottom on the graph. The other oxygen sensors seem much more stable. However the mechanic couldnt tell me if this is normal or not. I have ordered an OBDII reader from ebay which should arive soon. I will report actual readings as soon as I can. Spark plug leads and vacuum hoses seem fine aswell.

Thanks for your help guys. I really appreciate it.

Ray

[aspir3]

Is your car standard? Do you have any mods?

[SAM-24A]

I would take a look at the MAF (Mass Airflow Sensor)

You said your Lancer has traveled 120,000km, and I'm thinking no one has ever cleaned the MAF Sensor, not even Mitsubishi Pennant Hills who charged you $975

The MAF Sensor. Removal is Disconnect Wiring Harness & remove 1 screw.



The MAF Sensor is positioned on the Air Transfer Pipe from the Air Box > Throttle Body.



It can be spray cleaned using any product similar to Mass Air Flow Sensor Cleaner available from most Auto Parts stores.

[aspir3]

Sam I was thinking the same thing. It sounds like the issues people have when they fit short ram intakes as they mess with the air flow sensor

[Dire]

The only time I had idle problems was after I changed my intake and the hose had popped off the throttle body... So it could be the MAF

Should've been the first thing they checked
If cleaning it doesn't work maybe even try borrowing another one and seeing if it fixes it (pretty sure they just unplug?)

[Lancer1993]

Yeah you would think this is something a Mitsy dealer would have checked or cleaned. $975 is pretty high to fix a problem that is still there.

[JustinR]

I had idling issues on my 4B11T, took mechanics two days to figure out that a hose had come loose.

If you pop the engine cover off, take a look at the hoses around the engine bay, you might find the same issue.

[raihan_rahman03]

Hi fellas,

Sorry for the late reply and thanks for all the responses. I will be cleaning my MAF sensor and throttle body on Thursday. Do any of you guys know our cars have IACVs (Idle air control valve) in them?

Furthermore, does anyone know what the metal pipes are for on the top left of the engine bay? The one with a cap that says H (possibly for high) on it. I saw a drop or two drop out of that today.

My car is completely stock, and every replacement part is a genuine Mitsubishi part.

Thanks again guys,

Ray

[aspir3]

Do you have any pictures? There were a few air emissions changes with the lancers over the years.

[toc]

H = High, that would be the AC line high pressure side - Air Con related.

Do you have lumpy revs with the AC off?

Your best test is to take the car for a drive, take it home, leave it idle, and shut the AC and all other loads off (stereo, head lights, wipers).

If that solves it, then the issue will be the idle air control.
If it doesn't solve it, then the hoses Justin refers to is the most likely problem - vacuum hoses draw air back through the engine - if they come off, the engine gets more air then expected.

Find a new mechanic - $975 and not fixed is not where you should be going.

[BaronCJ]

Hey,
I've had the same issue with mine, the problem I found was an excess of buildup in the throttle body. I'd check that and clean it with some throttle body cleaner and see how that goes