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Eric
Eric, Automotive Repair Shop Manager
Category: UK Car
Satisfied Customers: 31345
Experience:  Automotive Repair Shop Manager, Technician/JA Mentor
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I have a 2004 Mitsubishi Pajero V6 gasoline engine. It has a

Customer Question

Hi
I have a 2004 Mitsubishi Pajero V6 gasoline engine. It has a problem with the idle. The engine starts normally, even in very cold weather (it goes below -20C or 0 F where I live). After 3 minutes of idling, the engine begins to rev up and down by itself and often sputters out completely. When the engine is very cold it does not do this. When the engine is hot it does not do this. It behaves like this in the in-between period between cold and hot. Sometimes, the engine dies while waiting at a red light and this is stressful for my wife when she is driving with the kids in busy traffic. While the car is moving, the engine sounds and drives very well.
I replaced the spark plugs, spark plug wires and there was no change. The mechanic took the top off the engine and I think he cleaned the throttle and there was no change.
The mechanics where I live lack the interest to help me diagnose this properly. They just suggest random solutions that don't make sense to me. I would appreciate your help to diagnose this.
Thank you
Don
Submitted: 1 year ago.
Category: UK Car
Expert:  Eric replied 1 year ago.

HI,

I am sorry that you have not been helped yet. I just came online and saw your question

If the engine is idling up and down rhythmically, this is a faulty IAC valve, located on side of the throttle body.

If it is erratic, then it is an air leak - vacuum hose, pcv valve hose, air intake tube or intake manifold gasket. With engine idling erratically, spray each one with some carb cleaner. The one you spray that causes the idle to smooth out is the culprit and will need to be replaced

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Customer: replied 1 year ago.
Hi. A few follow up questions.1. What do you mean by erratic? The tachometer fluctuation is dependent on the engine temperature. The tachometer fluctuates between 1500 and 400, then it sputters and dies.2. Please could you explain why the problem is dependent on the engine temperature (ie the engine is not very cold and it is not very hot, it is somewhere in between). How does your diagnosis take into account the temperature dependent nature of the idling problem?3. Please post photos of the parts and their location in the engine. I don't know how to locate the parts you mentioned.Thank you,
Don
Expert:  Eric replied 1 year ago.

HI,

erratic would be it dropping to say 500 rpms, then up to 900rpms, down to 600 rpms, up to 1200 rpms. all over the place

rhythmic would be dropping down to 400 rpms then up to 1500 rpms, repeating constantly and never varying in the low and high rpms it goes down and up to.

temperature can play a part as it causes metals as well a rubber to expand and contract, which if an air leak, will regulate when the unmetered air is entering the engine and causing the engine idle to act up. And it affects the IAC valve as engine temp affects it going into and out of closed loop operation which affects the IAC valve operation

I will see if I have a diagram with all the engine parts involved shown but not sure if I do

Customer: replied 1 year ago.
Hi,Can the IAC be fixed, or should I just replace it? Approximately how much does one cost and is it difficult to install?Thanks
Don
Customer: replied 1 year ago.
Also was wondering if you can write the part number. I live in a place where I have to buy the part myself and bring it to the mechanic.
Expert:  Eric replied 1 year ago.

HI,

Sometimes the IAC valve can be cleaned and it will resolve it, but normally it has to be replaced. It takes about 30 minutes or so to replace the IAC valve - sorry dont have the part number

Expert:  Eric replied 1 year ago.

I noticed we have not yet resolved your concern you asked about. I would sure appreciate it if you would reply so I can offer my skills and knowledge and repair guide access to help as best I can.

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If you have new questions now or in the future please do not hesitate to ask them. If you would like me to assist you. Just bookmark this page so you can access my profile easy and post a new question from the question box on my profile page. Please remember to rate service using the rating page so that I may receive credit. Thanks

Customer: replied 1 year ago.
Hi.
I don't understand the payment system. It said that I would be charged $5, and I was. But I was also charged an additional $13 (total $18 charged so far). How much more are they going to charge my card?
Expert:  Eric replied 1 year ago.

HI,

As an expert I dont know the billing procedures or charges, but I will be happy to have customer service contact you

Expert:  Eric replied 1 year ago.

I noticed we have not yet resolved your concern you asked about. I would sure appreciate it if you would reply so I can offer my skills and knowledge and repair guide access to help as best I can.

~Do you still need more help?
~Confused by my info request or answer?
~Need more time?
~Confused on how the site works?
~Need more detail or a different explanation?

If the answer is YES to any of these just press reply and lets work on this concern some more.

If you have new questions now or in the future please do not hesitate to ask them. If you would like me to assist you. Just bookmark this page so you can access my profile easy and post a new question from the question box on my profile page. Please remember to rate service using the rating page so that I may receive credit. Thanks