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Engine Cold Start [Lancer] [Efi]


Go to solution Solved by The Don,

Question

Greetings friends,

I've an issue with the Mitsubishi Lancer (2008 make).

Yesterday morning my car started normally and after the startup the RPM goes to 2k (which is normal) and in few seconds the engine made a sound like a cold start. RPM was fluctuating rapidly from 0.5 k - 2 k. It continued around 5 minutes and I didn't turn off the engine. After the heat was raised up to 50% the engine was acting normal, RPM came back to 0.7 - 0.8. During the time of the issue engine was clearly shaking (i opened up the bonnet and checked).

When things became normal I drive around and the issue never came later during that day. But it occurred this morning too, similar symptoms and the knocking was gone around in 5 mins time.

I've observed that it was smokey than before when this happens, and the smoke doesn't smell like patrol during that first 5 mins of start. (later it smells normal).

The common facts on these two days were the rain. There was continuous rain here and the environment is cold (below 20 c).

Now the milage goes as 88k and I have done a engine tuneup from Mr, Dhammika Frenando on the mark 82k (he changed the plugs and said there are no faults found by the scanner).

I've heard that EFIs doesn't have cold start (i'm not sure whether it's correct)

I'm planning to take her to the agents at Katugastota tomorrow,

I value any advice / ideas from experts.

Thanks a lot !

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You should first check the usual suspects. Mitsubishi's are notorious for rough idle issues though they are not too difficult to eliminate. The culprits on order of probability are:

1. The Idle control valve notorious for failure.

2. The throttle position sensor, probably just requires cleaning

3. The throttle body. When cleaning do not let anything fall into the icv socket or spray carb cleaner or something inside

4. Throttle body hot water line

5. vaccume leaks, from either a line or the throttle body itself

6 The ECU

You should not worry too much if it does not happen again. Sometimes the idle hunting you see, is the engine stalling and the anti stall kicking in to raise the rpm, and then trying to stall again.

Edited by The Don
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To begin with, your interpretation of a cold start seems to differ from that is generally in use. The usual definition of cold start is the higher-than-normal idle speed and the additional enrichment of the fuel mixture when the engine is cold. The ECU measures both coolant temperature and air temperature and decides on the enrichment of the mixture and the idle speed (2000 RPM in your case) based on the difference between the two. As the engine temperature goes up the idle speed comes down and the additional enrichment of the fuel mixture is taken off. In fact, all EFI vehicle that I know of come with this cold start phase.

Your problem could be due to one or more of the several factors. A tune up including a throttle body and IACV clean up should generally sort it out. What do you mean by exhaust being smokey? Is it white or black? Your comment on the exhaust smell is also confusing to me. An engine that has done only 88k should not produce any smoke unless there is some problem.

Edit: BTW the smoke that you see these days could be water vapor becoming visible due to cold climate.

Edited by Rumesh88
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To begin with, your interpretation of a cold start seems to differ from that is generally in use. The usual definition of cold start is the higher-than-normal idle speed and the additional enrichment of the fuel mixture when the engine is cold. The ECU measures both coolant temperature and air temperature and decides on the enrichment of the mixture and the idle speed (2000 RPM in your case) based on the difference between the two. As the engine temperature goes up the idle speed comes down and the additional enrichment of the fuel mixture is taken off. In fact, all EFI vehicle that I know of come with this cold start phase.

Your problem could be due to one or more of the several factors. A tune up including a throttle body and IACV clean up should generally sort it out. What do you mean by exhaust being smokey? Is it white or black? Your comment on the exhaust smell is also confusing to me. An engine that has done only 88k should not produce any smoke unless there is some problem.

Hi Rumesh,

Thanks, that was something I was not known. Looks like the cold start word itself if wrong for my case.

Actually what happens is the engine doesn't have a constant RPM when this happens, it's going to stop at one time and then it goes upto 2000 again and the RPM is rapidly fluctuating. There were no engine miss sounds but engine was shaking a lot when I looked at it.

Throttle body cleanup was done at the time the engine tune up was done.

And Yes it doesn't produce any smoke, but on these days the smoke was much noticeable even at normal conditions due to the low temperature. The exhaust was quite smoky and the color was white not black, the smoke came out smelled like burned oil and after 5 - 6 mins it started to smell like ordinary smoke with patrol smell. The white color smoke was also gone in that time.

And during the rest of the day issue never reoccurred upto now.

Edited by HashanJay
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You should first check the usual suspects. Mitsubishi's are notorious for rough idle issues though they are not too difficult to eliminate. The culprits on order of probability are:

1. The Idle control valve notorious for failure.

2. The throttle position sensor, probably just requires cleaning

3. The throttle body. When cleaning do not let anything fall into the icv socket or spray carb cleaner or something inside

4. Throttle body hot water line

5. vaccume leaks, from either a line or the throttle body itself

6 The ECU

You should not worry too much if it does not happen again. Sometimes the idle hunting you see, is the engine stalling and the anti stall kicking in to raise the rpm, and then trying to stall again.

Thanks Don !

I've get the #2 and #3 done by a mechanic.

Throttle body had some black dirt on that and cleaned it up along with the sensor.

I tried this morning but the issue didn't occur, being that today is also a cold day. Continuously I'll monitor. Thanks a lot for your advice and options.

Edited by HashanJay
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We had a similar problem with a X-trail 2001.

The culprit was a soaked air filter due to being parked in the rain.

The smoke must have had a "kara ganda"

I had a doubt of this too, I parked in the rain all night long but surprisingly it started without an issue. I think the TPS had the issue. Still monitoring!!

Thanks for sharing your experience mate !

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My Mitsubishi outlander 2008 has been having a very rough idle at cold start,misfires sometimes going off.This happens every morning .I have changed the MAF sensor, oxygen sensor, spark plugs ,fuel pump and filter and cleaned the throttle body.All this happens in seconds.Kindly advise what could be wrong

Edited by Kibugi
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1 hour ago, Kibugi said:

My Mitsubishi outlander 2008 has been having a very rough idle at cold start,misfires sometimes going off.This happens every morning .I have changed the MAF sensor, oxygen sensor, spark plugs ,fuel pump and filter and cleaned the throttle body.All this happens in seconds.Kindly advise what could be wrong

What petrol does outlander require to run? 92 or 95

and who recommend to change this all without proper diagnosis of the problem. You might’ve paid a hefty price for all of this by now. 

Edited by trinity
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