Tue Dec 08, 2020 7:04 am

Lurker
2007 MP3 250ie
Joined: 15 Nov 2020
Posts: 3
Location: Palm Desert, CA
 
Lurker
2007 MP3 250ie
Joined: 15 Nov 2020
Posts: 3
Location: Palm Desert, CA
Tue Dec 08, 2020 7:04 am linkquote
New here and impressed with the collective knowledge and wit. My recently acquired 2007 MP3 250 has 12k km and runs quite well (new battery, valve adjustment, tires, new voltage reg, throttle body cleaning including idle bypass port) with this one exception: when first starting, the throttle must be feathered for about 20 seconds or so until the ECU kicks in and then maintains at around 1800rpm. No problems after that. Otherwise it will sputter out. But if I don't take this step and take off directly after starting, it will stall when coming to a stop. I've twice cleaned the idle bypass port with no positive effect for this problem. Any ideas?
Thanks in advance!
Tue Dec 08, 2020 1:42 pm

Hooked
Piaggio MP3 500
Joined: 21 Nov 2017
Posts: 303
Location: Austin, TX
 
Hooked
Piaggio MP3 500
Joined: 21 Nov 2017
Posts: 303
Location: Austin, TX
Tue Dec 08, 2020 1:42 pm linkquote
Well, i think you're half right about the last one

Anyway, maybe it needs a fuel injector cleaning, since you've done everything else. At cold idle these things run open loop (oxygen sensor doesn't come into play) and the metering of the fuel is based on the throttle position and manifold pressure, and the injector is just assumed to throw the correct amount of fuel. Gunky fuel injector = too lean running at cold idle = stalling. Similar thing with the fuel pump putting out too little pressure.

Problem is, I don't know how to do it other than dumping some of the cleaner stuff into the gas tank and riding it.

I assume that the gas is relatively new, because old gas can cause idle problems too.
Tue Dec 08, 2020 7:11 pm

Lurker
2007 MP3 250ie
Joined: 15 Nov 2020
Posts: 3
Location: Palm Desert, CA
 
Lurker
2007 MP3 250ie
Joined: 15 Nov 2020
Posts: 3
Location: Palm Desert, CA
Tue Dec 08, 2020 7:11 pm linkquote
Thanks Squeazel! Gas is fresh. I've tried Techron injector cleaner a few times but doesn't hurt to try again. Is it difficult to remove and clean the injector directly?
Wed Dec 09, 2020 6:58 am

Hooked
2015 MP3 500 ie Business
Joined: 29 Oct 2019
Posts: 396
Location: Belgium
 
Hooked
2015 MP3 500 ie Business
Joined: 29 Oct 2019
Posts: 396
Location: Belgium
Wed Dec 09, 2020 6:58 am linkquote
Removing the injector won't get it any cleaner. Injector cleaning requires specialty equipment not available to the general public.

Outside of adding a cleaner to the tank supply, your only choice is to get a new injector if that is where the problem lies.
Wed Dec 09, 2020 9:39 am

Lurker
2007 MP3 250ie
Joined: 15 Nov 2020
Posts: 3
Location: Palm Desert, CA
 
Lurker
2007 MP3 250ie
Joined: 15 Nov 2020
Posts: 3
Location: Palm Desert, CA
Wed Dec 09, 2020 9:39 am linkquote
thanks sbaert. SW wants $109 for a new injector, so will try a couple more tanks of gas with inj cleaner and then possibly buy the new one if no improvement.
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