Gasoline Octane

[SunriseH2OSkier]

i was running 87 and noticed an occassional backfire so i bumped to 89.

backfire still there.  perhaps 1 in 10 or 1 in 15 during power up.  we do lotsa idling (to heat water for a shower in michigan) so i have been wondering if that is a problem.  2004 LCR.  anyone else backfiring?

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IIRC, you don't have a sensor to change the timing on the LCR. Jerry (Sunrise) can jump in here.

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true, no knock sensor.

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tvano and I talked about this a couple months ago, when the topic was hot on MBO. Based on what he described to me, I'm not sure what he's experiencing is a backfire - it's probably a fueling issue during extended idle, either too much causing a rich misfire (major hesitation followed by coughing and sputtering as it clears the fuel out of the cylinder on subsequent cylinder events), or too little causing a lean misfire (major hesitation followed almost immediately by full power as fuel gets squirted in on subsequent cylinder events). Either way, a knock sensor wouldn't help the situation as it isn't really an ignition timing issue.

[Wkerat]

It could be the computer reacting to cold water. I don't know about the lcr, but know some motors are set with a rev limiter that requires the engine to heat up before it will truly perform.

[whiteVLX]

It could be the computer reacting to cold water.  I don't know about the lcr, but know some motors are set with a rev limiter that requires the engine to heat up before it will truly perform.

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I've heard that too but I can't remember when that became reality. I'm pretty sure that does not happen with my 325 Monsoon.

[Wkerat]

I know the 340 monsoon does it, but am not sure on the others. My guess is they put it into effect in 03 or 04, but it seems like some motors are more touchy than others.

[SunriseH2OSkier]

My 2001 Sunsetter w/Monsoon 325 had the RPM limiting when cold. It is an interesting thought, though. Depending on how long you run the shower, could be replenishing the engine with the colder lake water, maybe enough to fool the ECM into dumping more fuel because it thinks the engine is colder than it is? Have to think about that one a little more...

[Wkerat]

Interesting idea. I know my friend who is a mechanic was saying that the cold water here was messing with the limiter on some Four Winns he was testing, because as soon as he hit the throttle the cold water would pull the temp below what it needed. At least they have a good waterpump/cooling system.

[whiteVLX]

It could be that I never noticed it because I have to idle out of a no wake zone and it's probably warm enough by then.

[VinRLX]

Steve, the rpm limit is progressive. That is, the limit climbs with the temp. So unless you hammer it within a couple minutes of start up you'd never notice.

tvano, Jerry, the issue described occurs during start-up or while idling?

[SunriseH2OSkier]

tvano describes it as the first launch after an extended idle (while changing skiers, running shower), and I think he indicated like a 1 in 15 occurrance. Engine is all warmed up, definitely not a cold start/RPM limiter issue.

[whiteVLX]

Steve, the rpm limit is progressive. That is, the limit climbs with the temp. So unless you hammer it within a couple minutes of start up you'd never notice.

tvano, Jerry, the issue described occurs during start-up or while idling?

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That settles it then. We're still fighting over who's getting in first and who's drinking coffee or beer.

[VinRLX]

tvano describes it as the first launch after an extended idle (while changing skiers, running shower), and I think he indicated like a 1 in 15 occurrance.  Engine is all warmed up, definitely not a cold start/RPM limiter issue.

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So a fuel delivery issue, then? Possibly a bad injector? At any rate, sounds like a good one for the mechanic to diagnose on a one year old boat.

Steve, you shouldn't fight over stuff like that. Coffee for the driver and beer for the guy who get's in first.

[whiteVLX]

tvano describes it as the first launch after an extended idle (while changing skiers, running shower), and I think he indicated like a 1 in 15 occurrance.  Engine is all warmed up, definitely not a cold start/RPM limiter issue.

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So a fuel delivery issue, then? Possibly a bad injector? At any rate, sounds like a good one for the mechanic to diagnose on a one year old boat.

Steve, you shouldn't fight over stuff like that. Coffee for the driver and beer for the guy who get's in first.

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Exactly, but when the weathers warm nobody wants to drive and when it's cold we all volunteer to drive.

[HoustonPerson]

Not to go completely crazy with a hi-jack or anything like that - LOL

But I did use 89 octane for the first time this last weekend...................it had about 1/8 tank of the 87 oct left in it....I added some fuel stablizer, and $50 of 89...for Saturday................it purred like a kitten..........I think it might of run a little smoother.

Hey yesterday 87 was $1.99

89 at $ 2.07

92 at $ 2.15

diesel at $ 2.16

Feels like the old days LOL

[UWSkier]

On the topic of rev-limiters, for '02 Indmar put a rev limiter on the Monsoon. They had issues with them conking out when cold. An injected motor should never clunk out like that. For '03, they programmed in the idle flair to compensate, which it did, but made slow speed use kindof a PITA. For '04 they toned down the idle flair and the Monsoon ran as good as it did in '01. Basically they had to correct a problem they created by introducing something to correct a problem that was introduced to correct a problem that never really existed in the first place...

[Greg_S]

i just picked up my VLX with the Monsoon the other day and my salesperson was pretty adamant about using anything more than 87 was a waste of money. I asked him several times because of posts like this.

Greg

[whiteVLX]

i just picked up my VLX with the Monsoon the other day and my salesperson was pretty adamant about using anything more than 87 was a waste of money. I asked him several times because of posts like this.

Greg

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Funnily enough the mechanic at my dealership said the very same thing.

[andyb]

There is 5 cents a litre difference between 91 and 96 octane gas here. I use 96 octane in the Hammerhead to make it happy. Incidentally, the gas works out to $5.82 a gallon vs $5.60 for 91.

[TOAST]

There is 5 cents a litre difference between 91 and 96 octane gas here.  I use 96 octane in the Hammerhead to make it happy.  Incidentally, the gas works out to $5.82 a gallon vs $5.60 for 91.

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Looks like the crew in the US can stop complaining about high gas prices!

[Malibudoc]

There is 5 cents a litre difference between 91 and 96 octane gas here.  I use 96 octane in the Hammerhead to make it happy.  Incidentally, the gas works out to $5.82 a gallon vs $5.60 for 91.

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It is interesting that much of the cost of gas goes to road taxes as previously described. I wonder if boats should be exempt of paying that tax as obviously we don't use that gas on the ROAD??? I'm not sure how you could regulate this, but seems like a logical debate!

I believe that this would pertain even more in foreign countries where taxes are an even greater portion of the cost.

[andyb]

There is 5 cents a litre difference between 91 and 96 octane gas here.  I use 96 octane in the Hammerhead to make it happy.  Incidentally, the gas works out to $5.82 a gallon vs $5.60 for 91.

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It is interesting that much of the cost of gas goes to road taxes as previously described. I wonder if boats should be exempt of paying that tax as obviously we don't use that gas on the ROAD??? I'm not sure how you could regulate this, but seems like a logical debate!

I believe that this would pertain even more in foreign countries where taxes are an even greater portion of the cost.

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That's so true. Recently another 5 cents/litre was added to fund new national roading projects.

[andyb]

The cost of gas is not quite as bad as it looks.. our gallon has 4.55 litres in it making it around 1.2 US gallons. In NZ a US dollar buys around 1.2 Kiwi dollars so as long as you were using income gained in the US, the personal cost would be around $US4.04 a gallon unless I stuffed up somewhere.

On the positive side, you probably don't have to pay to launch your boat, you won't get bitten by a crock or shark (unlikely) and the beer is better. LOL.

[waimo]

HI andyb we feed our monsoon on 96 on the advise of its longer shelf life good to see another kiwi on here

[andyb]

HI andyb we feed our monsoon on 96 on the advise of its longer shelf life good to see another kiwi on here

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Hi Waimo - I knew we were a rare breed & now there are two of us. That's 100% increase!

[D-GOOSE]

I run 87 in my 03 monsoon. It seems to run fine but will be using 91 for my last and first tank of the yr. Know I just have to figure out when my season ends.

[Malibudude]

Spend whatever you're wallet will allow, mine is 87.