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Discussion Starter · #1 ·
I recently picked up a stock 2000 Eclipse RS and everything is golden on it but I wasn't too happy with the idle. The Idle is around 500-600 rpms and causes a slight vibration throughout the car. Playing with the throttle, the vibration goes away around 850 rpms, so that was what I was shooting for. (No SES light on and the bulb works).


I went straight to the IAC motor on the bottom side of the throttle body. I turned the key to ON and tested the voltage on the harness. It matched the battery's voltage load so I pulled the IAC motor off and it ohmed out at 32 ohms top and bottom. The motor was clean but I hit it with some carb cleaner and a shop rag for safe measure.

Next thing was fuel filter. Only problem was, it's in the tank and doesn't require replacing. So I assume the fuel pressure is up to par.

Plugs and wires were recently replaced.

I know the target rpm for idle is tuned in the ecu and won't change regardless of what you do electrically or mechanically in the engine bay, that is IF everything is working in range. I toyed around with the biss screw to try and trick the ECU into what I'm trying to get it to do. My solution: Basically you have to turn it so far out that it's just out of closing range of the IAC motor WHEN WARM. On cold start ups the idle does it's thing to get the oxygen sensor heated up then at operating temperature it's right where I like it, 850 rpms.
 

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I think our cars are supposed to idle between 500 and 700. You can always reset the ECU by unhooking the battery for a few minutes then letting the car idle for at least 20 minutes.
 

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Discussion Starter · #3 ·
I think our cars are supposed to idle between 500 and 700. You can always reset the ECU by unhooking the battery for a few minutes then letting the car idle for at least 20 minutes.
I think you're right. I think Mitsubishi half assed the tune and didn't want to make a separate tune for the manual tranny. (Auto's have to idle low so the torque converter doesn't sit there and slip).

I really wouldn't mind the low idle but I do mind the vibration.
 

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I think you're right. I think Mitsubishi half assed the tune and didn't want to make a separate tune for the manual tranny. (Auto's have to idle low so the torque converter doesn't sit there and slip).

I really wouldn't mind the low idle but I do mind the vibration.
Close...if the engine is turning but the vehicle isn't moving, the torque converter is doing nothing but slipping. In fact, the only time a torque converter truly doesn't slip is when it is electronically locked up, on models so equipped...what you need to avoid on an automatic is the torque converter reaching its stall point...:bigthumb:
 
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