Mitsubishi L200 rough idle (diesel)

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Mitsubishi L200 rough idle (diesel)

Postby RYM6746 » Sun Feb 19, 2017 11:26 am

Hi guys I have a diesel 2004 mitsubishi L200 that starts and runs fine it has an extremely rough idle when cold, to the point where it will actually cuts out. As it warms up it slightly improves (doesn't cut out) but is still rough. I have disconnected EGR with no change and checked the throttle valve operation. It has a conventional fly by wire diesel pump. No fault codes and scan data looks good. If you literally touch the accelerator pedal to hold the revs up slightly it will idle fine. I have found a good video on you tube which matches the symptoms https://youtu.be/2bEExs_K78E
Looking at scan data the engine speed and pump speed at times do differ slightly as it does in the video (it can be seen more clearly if you graph the scan data). Does any one have a good crankshaft and pump corrilation waveform? And is it possible to see the "slack between the two" on the pico? As I have no injector or spark to trigger from. I want to be 100 per cent sure I am dealing with the same fault in the video before I strip down the front of the engine to check it out. I am struggling to find the pump speed sensor on the pump any help on this will be much appreciated. Thankyou for your time.
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Re: Mitsubishi L200 rough idle (diesel)

Postby RYM6746 » Tue Feb 28, 2017 12:35 am

After scoping the crank and pump speed signals and not seeing any "drifting" between the two. It turns out that the accelerator pedal position sensor can be adjusted. So moved it to the upper range of its tolerance and the idle moved with it, so I called it a fix.
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Re: Mitsubishi L200 rough idle (diesel)

Postby STC » Tue Feb 28, 2017 12:45 am

Good Find Rym. Well done :)

One to save in the "Knowledge Bank" I reckon some "Experts" would have rebuilt the front end of that engine based on the video alone.

Thanks for the Feedback
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