Thread: Rough Idle NA MR-1 Engine
12-26-2009, 08:43 AM #1
Rough Idle NA MR-1 Engine
I have a couple of skis with MR-1 engines that are naturally aspirated engines installed. I have had problems with a rough idle on one of the skis since I purchased it and the dealer was no help. I did check the coils per the service manual and didn't find any issues. Here is another interesting fact that I found out recently. I was wondering if someone could better pinpoint the trouble based on this symptom.
Ok - so I know this isn't how I normally should do it - but we were thinking safety. Due to some medical issues with my Daughter, I didn't get around to changing the oil in either PWC until a couple days ago. It was a balmy 38 degrees F outside, so my son and I opened all 3 garage doors and pushed the ski 1/4 way out of the garage (but not completely so it would be somewhat warm when changing the oil). We put a digital CO monitor in the garage and fans to clear the air after the engines ran for ~10 minutes to warm the oil. We started the engine and went outside where we could monitor the CO levels safely.
Here is the interesting fact - on the ski with the rough idle engine the CO level was more than double (~520 ppm) than the smooth idle engine (~180 ppm). So, I am assuming that the likely causes are still injectors or coil packs, right? Anything that can lead to incomplete combustion and produce more CO? Any other ideas??
12-26-2009, 01:09 PM #2
Put new plugs in, right? I'm sure you have already but just throwing it out there.
When I had my VX new plugs solved the rough idle issue.
12-26-2009, 08:19 PM #3
I have 2 of those motors in my jetboat,and they're notorious for fouling plugs....especially if you're not wot alot of the time. I actually went one heat range hotter(my local dealer recommended it) and haven't fouled a plug in a year....bulletproof motor(loud as hell though!!)
12-27-2009, 08:56 AM #4
Great suggestions, but one of the first things I tried was to upgrade to the iridium plugs on both skis. Changed the stock resistor plugs before that with no real change in symptoms. Given that I can check the COPs via the manual, I am leaning to the injector spray pattern. BTW - I did swap COPs with the other ski to see if the problem moved and it did not.
Is there anything else other than the injectors that could cause this?
12-27-2009, 04:29 PM #5
Back to basics, check the fuel pressure, I am not familiar with your model but if you suspect a rich mixture I would be checking to see if the regulator is doing its job. A pain to connect up though.
12-27-2009, 05:34 PM #6
try reading the co level on both at just above idle
as i think it may just be the balance of the throtle bodies
have a look at the buterfly's on both skis and see if there aligned diferently
12-27-2009, 08:33 PM #7
12-27-2009, 08:34 PM #8
12-28-2009, 05:20 AM #9
What model do you have? this is important as there are differant MR-1 set ups.
If a HO, then check all bypass motor connections......they can come loose, if one is off then this will cause a rough idle.
12-28-2009, 07:32 AM #10
The motor is a Non-HO motor. Single throttle body.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By hotrod_sxty8 in forum 2-Stroke PerformanceReplies: 8Last Post: 05-20-2007, 11:27 AM
By Rio Vista in forum Yamaha Open DiscussionReplies: 5Last Post: 03-13-2007, 01:33 PM
By njgprider in forum Yamaha PWC Performance (2-stroke)Replies: 1Last Post: 10-05-2006, 09:02 PM
By flyboy in forum Yamaha PWC Performance (2-stroke)Replies: 1Last Post: 08-16-2006, 03:22 PM
By Snoman in forum 4-Tec PerformanceReplies: 10Last Post: 07-11-2006, 01:33 PM