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Lancer CS1 Idle Issue

Piranavan Lancer CS1

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@DavyHi Mr.Davy. I have a lancer cs1 gl 2007. I came across this iac valve problem and bought a reconditioned iac valve and fixed it. But I the problem is not solved still.

1) engine is set to 1100rpm to not make the engine stall when ac on.

2) Even thou its in 1100rpm still the ac cutoff cuts off the ac cuz of the low rpm created when on the ac

3) I am not sure but I feel my ac gives more stress than other cars cuz we need to press the accelerator twice more u press it before!

So please can u help me out with this. @Sampath nalinda Gunasekara recommended about u. Thank You!

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Hi @Piranavan Lancer CS1, Welcome to the forum.

My first guess is that the reconditioned IAC valve is defective. But before concluding, can you answer the questions below:

1. In point #1 you mentioned that the "engine is set to 1100rpm". Do you mean that the idle RPM is manually set to 1100 using the idle adjustment screw on the throttle body? If this has been done, it needs to be reset to factory position.

2. Before fixing the new IACV, was it cleaned with contact or throttle body cleaner? If yes, how was it cleaned? Was the liquid sprayed directly onto the IACV?

3. When you start the car in the morning, does the RPM rise to around 1000 - 1500 and slowly settle at normal (in your case 1100) when the engine reaches operating temperature?

4. Can you provide a bit of history on the car? Current mileage, mileage since last fuel system clean-up (tune-up) etc.

As for your point #3 about AC putting excessive stress on the engine - it's quite normal to feel that way on a CS1 because it's a small engine on a mid-sized sedan. But if you have compared against other CS1 Lancers and feel that yours is noticeably underpowered, then it could be an issue. You can start by checking whether the AC/Accessory belt is over-tightened or whether the AC compressor is binding. If these are Okay, you're probably looking at a fuel system issue.

Edited by Davy
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Hi Mr.Davy I'll answer with the question numbers!

1)Yes he adjusted the screw in the throttle body which rises and lows the idle. How can it be reset to factory position?

2)Yes it was cleaned with Wurth Injectors and Carb Cleaner. It was sprayed totally onto it in all sides.

3)Nope it doesnt rises up (u meant the cold startup rit?) nope bro 

4)91k now and tuneup was done at 85k (did the injectors cleanup and orings were replaced and throttle body cleanup and spark plugs checked and they were ok. at 76k we did it at Unit#d Mot#rs)

Ill check whether the ac belt is overtightened. But wat is Compressor Binding BTW? 

I dont think there is a problem in the fuel system cuz i can pop off a 0 to 100kmph in 12secs which is gud for this car!:)

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1. The idle screw on the throttle body is not meant to be adjusted. It's preset to match the engine and ECU combination the throttle body is fitted to. Most local mechanics who want a "quick fix" try to solve issues by messing with the idle screw, but it throws the ECU off completely which is why you are currently experiencing issues.  

There is usually a mark (like a torque seal mark that comes on nuts and bolts from the factory) on the idle screw to indicate the factory position. But it won't be easy to determine how many turns the screw was moved. So your best bet is to take the car to the agent and let them reset it for you.

2. Wrong again. The plunger type IACVs that come on these Mitsubishi engines are highly sensitive to cleaning liquids. What happens when high pressure liquid is sprayed onto the plunger is that the carbon already on it is carried into the unit which shorts out one or both coils within the unit and destroys it. This becomes worse if the IACV is installed immediately after cleaning without allowing it to dry properly. The workshop manual warns against using any form of aerosol cleaners on the IACV, TPS and the throttle body as well for that matter. So my guess is that this recon IACV is also now defective.  Take your car to the agent and they should be able to test it for you.

3. This further confirms that your IACV is defective

If at some point you had your AC system serviced/repaired and they re-filled with refrigerant, and if they under-filled it, your compressor would have "starved" of lubricant which would have worn out. This happens more often than you'd think. If your AC belt was too tight, it would wear out the bearing on the compressor pulley and cause it to bind/stick. So when the AC is turned on, the engine has to deal with more load than normal. 

Edited by Davy
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