Buddy asked me to post for him.
Says that his 08 200 Opti will keep a fast idle for some time after coming out of gear. Says its definitely not normal. If he drives or even idle speeds somewhere, as soon as he puts it in Neutral the idle stays high for up to 10 sec. or so then will come back down to normal idle.
Whats going on? Wondering what he can look at before having to bring it in?
Derek Chance
2021 Nitro Z19 Pro 200 Mercury ProXs
BTS and KVD Line and Lure
First place I would look is to confirm throttle is CLOSING completely (and arm is returning against it's stop consistently).
Second, I'd confirm TPS voltages/function via a "Sweep Test".
If everything above checks out ok, move on to AIR/FUEL pressure tests, including both pressures:
-At idle
-5 seconds after engine off
-10 seconds after engine off
-15 seconds after engine off
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Ok Don. thanks.
What is the Sweep Test? Is that something he has to take it in for or can he do it?
And same question for the Air/Fuel pressure tests.
Derek Chance
2021 Nitro Z19 Pro 200 Mercury ProXs
BTS and KVD Line and Lure
Due to the type of equipment required, it's probably going to be best to take this in for these tests.
TPS voltage sweep test involves monitoring the TPS voltages with the Computer Diagnostic System, while operating the throttle from IDLE to WOT and back several times. Voltage increases and decreases should be consistent, with no "glitches". Also, tapping on the TPS with a #2 pencil eraser at idle will often show if there are glitches present AT IDLE.
Air/Fuel pressure tests require a DUAL pressure instrument with liquid-filled gauges. Monitor both pressures at idle, NOTE THE DIFFERENTIAL in pressures, and then monitor pressures and differential after engine shutdown (5 seconds, 10 seconds, and at 15 seconds after shutdown).
If the differential disappears before 10 seconds... there's likely a leak somewhere in the system.
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 48 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Mine was doing that and it was my hot foot not returning all the way. Have to keep pulling it back with my foot.
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