Engine Is Unstable And Stops When Idle (Pajero Io )

chamila33 · July 24, 2011

hi ,

i have a mitsubishi pajero io which is around 10 years old . when the car is idle ( neutral) as in when stopped at a traffic light the engine weakens (you can c the rev indicator going up and down )and most of the time dies out eventually . it can be stopped by pressing on the accelerator at which time the engine stays on . this problem has been around for some time . will an engine tune up fix this ? i have tried cleaing the idle valve with the spray but that doesn't seem to work pls help me !

Magnum · July 24, 2011

On 7/24/2011 at 3:50 PM, chamila33 said:

hi ,

i have a mitsubishi pajero io which is around 10 years old . when the car is idle ( neutral) as in when stopped at a traffic light the engine weakens (you can c the rev indicator going up and down )and most of the time dies out eventually . it can be stopped by pressing on the accelerator at which time the engine stays on . this problem has been around for some time . will an engine tune up fix this ? i have tried cleaing the idle valve with the spray but that doesn't seem to work pls help me !

i think your having a problem with the air filter, or it could be an effect of the bad fuel!

ShintaroX · July 24, 2011

Just as an aside, is it a GDI? and what fuel are you pumping? GDI cars on low-quality petrol have had issues with blockages in injector flow, have you investigated this?

Some of these ios have had a few throttle body issues too which carried similar symptoms to what you are describing.

Edited July 24, 2011 by ShintaroX

miniace · July 24, 2011

GDI is very sensitive to fuel quality. Normally our fuel contains a higher Sulfur percentage and that damages the buried nozzles.Try a tune up from a good place and do a scan and see.Whatever the case, not a big issue and can be sorted out in one stop.

MINIACE

Archon · July 25, 2011

On 7/24/2011 at 3:50 PM, chamila33 said:

hi ,

i have a mitsubishi pajero io which is around 10 years old . when the car is idle ( neutral) as in when stopped at a traffic light the engine weakens (you can c the rev indicator going up and down )and most of the time dies out eventually . it can be stopped by pressing on the accelerator at which time the engine stays on . this problem has been around for some time . will an engine tune up fix this ? i have tried cleaing the idle valve with the spray but that doesn't seem to work pls help me !

dear chamila, check the engine for timing,, have you replaced your timing belt or chain at the specified correct time? then check the "throttle air bypass valve" (located in the throttle body)is correctly functioning coz its responsible to control air when the engine is idling, and check its bypass cavity is not blocked by dirt and debris finally check the MAF sensor if your jeep have one. coz bad MAF (mass air flow sensors) are known to cause this type of rpm behavior.

Also you might find this manual useful http://www.mivec.co.nz/tech/4G9x_Engine_Manual.pdf

Cheers,

Archon

Edited July 25, 2011 by Archon

harshansenadhir · July 25, 2011

On 7/24/2011 at 3:50 PM, chamila33 said:

hi ,

i have a mitsubishi pajero io which is around 10 years old . when the car is idle ( neutral) as in when stopped at a traffic light the engine weakens (you can c the rev indicator going up and down )and most of the time dies out eventually . it can be stopped by pressing on the accelerator at which time the engine stays on . this problem has been around for some time . will an engine tune up fix this ? i have tried cleaing the idle valve with the spray but that doesn't seem to work pls help me !

throttle body clean up with injector pressurizing would sort out lot of rough idle issues. If it further persists, check the throttle positioning sensor (TPS) and throttle gate itself for improper closings/openings for idle setup.

jdnet · July 25, 2011

Go get a diagnostic done at United. Taking it there is a lot better than getting random opinions on the forum. They do not charge for the diagnostic AFAIK. They should be able to tell you if there are fuel pressure issues. If so the problem is with the fuel regulator (also called GDI pump). The pump would need to be replaced.A replacement pump will cost about 60k. Although there is a way I have tried and succeeded in getting it back to life. Too lazy to explain the whole process. Let me know after you confirm wether or not it's the pump and I'll tell you what to do.

chamila33 · July 25, 2011

On 7/25/2011 at 4:23 PM, jdnet said:

Go get a diagnostic done at United. Taking it there is a lot better than getting random opinions on the forum. They do not charge for the diagnostic AFAIK. They should be able to tell you if there are fuel pressure issues. If so the problem is with the fuel regulator (also called GDI pump). The pump would need to be replaced.A replacement pump will cost about 60k. Although there is a way I have tried and succeeded in getting it back to life. Too lazy to explain the whole process. Let me know after you confirm wether or not it's the pump and I'll tell you what to do.

hi thanx 4 ur reply . this issue has been there in my car for a long long time now ( like 2 or 3 years) when i go to my regular garage and tell him about the issue he takes the engine apart and sprays wb40 on the air valves but that doesnt seem to help . is there a full diagnostic at united? if so how much does that cost? do u have any idea how much they charge for an eingine tune up cus i think that is the issue here .

thanx again 4 all the help

chamila33 · July 25, 2011

On 7/24/2011 at 4:22 PM, miniace said:

GDI is very sensitive to fuel quality. Normally our fuel contains a higher Sulfur percentage and that damages the buried nozzles.Try a tune up from a good place and do a scan and see.Whatever the case, not a big issue and can be sorted out in one stop.

MINIACE

where can i get a tune up done ? any good place ? how much will it cost me ?

chamila33 · July 25, 2011

On 7/24/2011 at 4:11 PM, ShintaroX said:

Just as an aside, is it a GDI? and what fuel are you pumping? GDI cars on low-quality petrol have had issues with blockages in injector flow, have you investigated this?

Some of these ios have had a few throttle body issues too which carried similar symptoms to what you are describing.

yep its a GDI ! we normally pump 95 but we did pump 93(the extra premium ) a few years back for a very short period but stopped that very quickly . how do i check the injector flow?

ShintaroX · July 26, 2011

I had a GDI myself and Unit#d Mot#rs cleaned the injectors (which are in the combustion chamber unlike the multi-ports), replaced the shattered magnet in the throttle body (caused due to carbon build up probably), ran the diagnostics, de-carbonized the engine etc. but to no avail, you will have to live with that one mate, sorry! Unless they've come up with a solution recently. I wrote to Mitsubishi at the time who explained that it is due to our sulphur levels in the petrol, the same issue is in Europe as well apparently. The Sulphur levels being too high cause misfiring during idle.

Sorry mate.

chamila33 · July 27, 2011

On 7/26/2011 at 2:54 AM, ShintaroX said:

I had a GDI myself and Unit#d Mot#rs cleaned the injectors (which are in the combustion chamber unlike the multi-ports), replaced the shattered magnet in the throttle body (caused due to carbon build up probably), ran the diagnostics, de-carbonized the engine etc. but to no avail, you will have to live with that one mate, sorry! Unless they've come up with a solution recently. I wrote to Mitsubishi at the time who explained that it is due to our sulphur levels in the petrol, the same issue is in Europe as well apparently. The Sulphur levels being too high cause misfiring during idle.

Sorry mate.

im sorry to beleive this and i think its just a case of a tune up because when the vehicle is at a stop if i press the accelerator ever so lightly the engine works perfectly without being unstable ! so if anyone could jst tell me where and ow much an engine tune up would be that would be great !

ShintaroX · July 28, 2011

Yes I had the same issue machan, even on N when there is the instability, a slight accelerator press gives the impression of stability. Unless some new solution is out there, there is nothing that can be done about this. For months my car was at Unit#d Mot#rs and we couldn't solve it, we just left with the idea conclusion that it was an issue with the injectors from the petrol. But I see you're a glass half full kinda guy, so for a tune-up try Unit#d Mot#rs in Orugodawatta, not sure of the cost, just give them a call and I wish you the very best of fortune in this, let me know if you get it sorted.

toyota sucks · July 28, 2011

On 7/27/2011 at 6:03 PM, chamila33 said:

im sorry to beleive this and i think its just a case of a tune up because when the vehicle is at a stop if i press the accelerator ever so lightly the engine works perfectly without being unstable ! so if anyone could jst tell me where and ow much an engine tune up would be that would be great !

I had a similar problem in a 1.5 vvti nzt 260 premio (but hen the accelarator was released after going at a high rpm)

went to the company they plugged the computer said an injector cleaning would do but the problem persisted,

so got rid of the car that's the best solution if u can't live with it,