4 Cycle Engine Owner/ Missing / Idle Problems

[Occams Razor]

Hello All !

I will try from now on to make my post more readable, sorry. I get going and the next thing I know a short novel.

Anyhow poking through the post I have seen many question Idle issues and stalling with these 4 cycle fuel injected engines.

Well I am going to give you a little secret that is overlooked even at the service shops. Fuel injected 4 cycle outboards take

after their automotive bretherin in technology. So what you are seeing on the water has been in the automotive field for

10 years at least in most cases. What we are concerned with her is poor idle and or stalling on start up or quick in gear load.

What controls the idle of the engine idle under load at idle is called a Idle air actuator. This little actuator is elecronicly

controlled and adjust the air flow around the throttle plate to allow the engine to run smoothly under load. Now this takes

a few seconds to adjust and that is why sometimes it is rough idle and after a few seconds it smooths out. Once this takes

you are pretty well assured that the Idle air control is working. Now for the secret (not to the automotive guys) , the throttle

is adjusted slightly off closed angle to allow a metered amount buy to let the engine idle, other wise if you slapped the

throttle shut quickly the engine would stall so there needs to be air allowed by the throttle plate to keep the engine from

stalling. Now what happends with 4 cycle engine is during the combustion process acidic acids develope in the crankcase

and accumulte in ithe intake system in the form of a soft cabon. This accumulation develops on the back side of the throttle

plate and around the bore the plate operates in. Now what this effectively does is constrict the air flow over time nearly

cutting off the air flow needed to allow the engine idle. The reason it does not show up until it cause problems is because

Idle Air Actuator is adusting slightly to compensate for the lack of air bypassing the throttle plate. Now once the buildup is

sever enough we run into a stalling condition on initial start up and quick in gear load. The fix is somewhat easy. Some like

to use carb cleaner or seafoam but they are very strong carbon breakdown agents and can ruin the teflon finish use in some

outboard throttle bodies. I suggest using good old WD-40, is is a very good soft carbon cleaner and will not harm your

throttle bore if it is coated. Soak a soft shop rag with the WD-40 and once you have gained acess the your throttle body

plate (butterfly) open it up Fully and carefully wipe the buildup uf sludge from the back side of the plate and around the

circumferance of the bore it sits in. Make sure its comes out clean and shiny ! Wipe it out dry with a clean rag and asseble

all that was dissasembled to gain access. Fire it up and see the difference ! Minimum Idle air bypass is very important in

fuel injected 4 cycle engines.Once a year is usually all that is needed. Keep em running smooth !

[aluminumdreamer]

I know that almost always smooths the idle or fixes the start and stall on drive by wire Toyotas that I work on. In fact I had one today at work, cleaned the throttle body and it was mint. It sounds like what you are saying would make sense on a 4 stroke outboard. I don't have a 4 stroke but when I do I'll remember that little trick.
Nate

[welder]

Had to do that a couple times on my 460 CID , works like a charm and the WD40 is the way to go so you don't take off a teflon coating or the like .

Good post AR.

[JETTYWOLF]

That's all so well & good.......but ya wanna know what that read like to me?

"Goobliy gook (**^&^$&&_)(*&^%$&()_POIUYTGFRGHJK<L>:?"LKJIUH%^BNM<)&(*BM}{"P:?OY&U^%T%@%$%#^&*()+{}
P:">?<>MNBHJVHTYR%^#%$ES%RESXD^%&*)Y(U)PI{)O"":LOKJH<GXZSDW#$%^Y&UJMN<>L:OP{)":?L><MN HJYU^TGHBN V BVFVGRE#EWSDVC NNMHJYU^&U*IOL:?><M BVFGDERW#@WQASDERFTYUIOP:"??>UJN*IKM)OL<P:^T%FGVEDSCQAZXCVBNPOIUTRGFHBRFVBIIOK<M ......."

Yep, probably the same thing that it would be like for me telling you how to float-rig fish for Trout in the St. Johns River.

I fish. I not a mechanic..... :-?
I'd do better with a picture, because I have my Honda Shop manual now!!



I GET A 'LOPPING" AFTER START UP, AND THEN IT GOES AWAY.

[21ftcc]

Yeap have to agree with Jetty, that was harder to read then my database management systems or my discrete math book; and just for Jetty.

Discrete mathematics is the study of mathematical structures that are fundamentally discrete rather than continuous. Real numbers and rational numbers have the property that between any two numbers a third can be found, and consequently these numbers vary "smoothly". The objects generally studied in discrete mathematics – such as integers, graphs, and statements in logic[1] – do not vary smoothly in this way, but have distinct, separated values.[2] Discrete mathematics therefore excludes topics in "continuous mathematics" such as calculus and analysis. Alternatively, discrete mathematics can be characterised as the branch of mathematics dealing with countable sets[3] (including rational numbers but not real numbers), but there is no exact, universally agreed, definition of the term.[4] It is more what is excluded (the notions of a continuously varying quantity and related notions) than what is included that describes discrete mathematics. The term finite mathematics is sometimes applied to parts of the field of discrete mathematics, particularly areas relevant to business.

[JETTYWOLF]

I'm sure I forgot somethings about fishing that I could fluster you with, cuz it's all I breath....I'll add these also :lol: :lol:


Off the topic a tad,

I took a Engineer from Parker Filtration/Racor out fishing last winter, and he said that the 2 micron filters are developed for the ethanol /water absorbing -problemos, and that even if I have no "problemos" I should try one.

Problemo: Can't find the one I use in ""2 micron""........DOH!!! :roll:


Talked to a long time Capt/Guide from WAY WAY back this morning at the bait shop who also owned a boat dealership and bait shop. He asked what are we gonna do when they up the ethanol?

Hell I just bought a brand new TROY BUILT lawn mower yesterday and it says; DO NOT EVER USE FUEL THAT HAS MORE THAN 10% ETHANOL IN THIS ENGINE!! Right on a big BACK SIDE sticker on the top.

UT OH... :shock:

[welder]

It's real simple guys, AR is talking about removing the lite carbon build up in the air intake [ Back of the butterfly on my 460 ]

The carbon builds up and seals up the small , permanently open air passage that allows your motor to breath at a idle.

As the air passage begins to clog up your truck/motor will start to idle rough , slower and the motor may die when you come to a stop or when the high idle turns off.

Oh, this is the MOTOR forum so pay attention y'all.

[21ftcc]

So it sounds like its the MAF or IAC in a car. It builds up with carbon and next thing you know the engine light is on.

Also Baldwin or Napa sells 2 micron filters.

[JETTYWOLF]

That fit my Racor bowl???


Hey 'W',
the next time we talk on the land line you can tell me more about checking the carbon deal.
I have more of a "lopping" when the engines cold at first, rather than conking out. It doesn't conk out, hardly ever.
My mechanice said all ya have to do is adjust that thing there (him pointing to what I don't know). Looked it up in my shop manual and still said to myself....."Self, I'm still not farking with it, since it's all foriegn to me!!"

Lawn mowers? Now we're talking.

[welder]

10-4 Dave , Carbon talk on the Land Line .

[21ftcc]

Jetty,

Might want to check this out. The "iac" - idle air controller, which builds up with carbon is under the warranty replacement parts. If you going to try and clean it out you will want to use throttle body cleaner and try to keep the cleaner off plastic parts as it will eat at them slowly. There is also connection cleaner that can be used on plastic parts.

http://www.honda-marine.com/pdfs/Emissi ... rranty.pdf

[Merlin]

This is great info and a huge help. I'm one of the guys living with these "challenges". I have a question for you since it sounds like you have a bunch of experience and seem to know what you are doing:

Could this escalate to the point of fouling spark plugs?

My motor really started running rough and got to the point where it was fouling plugs pretty rapidly. I've gone through all the tune-up stuff and, just by coincidence, cleaned out the air intake/throttle body the other day before I read this. The boat is running better but I need to run it more to make sure - no problem since the fishing has finally turned on. I've also been running some injector cleaner to see if it's the injectors that are clogged and causing the plugs to foul - hoping this will clean them out.

Oh, what do you think of Yamaha Ring Free? I'm thinking of doing another shock treatment before I change the plugs.

[IN2DEEP]

Merlin,
Have you checked your thermostats?
I just saw someone asking about a problem that he was having and one of the suggestions was to check the thermostat.
If your thermostat is sticking open, then the computer will think that the motor is cold and over inject the fuel to compensate for the cold engine temp.

Just a thought,
Scott

[JETTYWOLF]

Hmmmmmmm...
I broke open my "shop manuels"....and did some Manuel laborski.

I took off the air intake hose dealie, and looked at that "butterfly" front and back....figgered back is where that Carbon build up is, right?

So I gotz out me WD-40, 20 ouncer and put some on the end of a new clean towel corner and tried my hand at removing nothin more than a slight discoloration???

Saw me no carbon, and it - the butterfly, didn't want to open all the way, tried moving the cable on my Honda to get to the back side a bit better. But really I didn't see no Ill effects in there.

I wanna know what to do about the "lopping" of the engine I get as it warms-up after sitting and running for the first few minutes.

My USCG Honda 225 mechanic buddy who was at the house one day said....."Oh yeah it's that lil screw adjustment, right there." as he pointed and I looked and wasn't really getting the idea.
We were at that time worried about the ticking in the lower unit that ended up being a chip in a tooth in the gear that warrenty fixed.

Lopping????

C'C' mon.............. Occams Razor, ya on this channel???

[welder]

Dave next time it starts loping try squeezing the bubble and see if it stops .

Could be the High pressure fuel filter.

[Merlin]

Scott,

Thanks for the tip. I've been working on this motor for some time now, searching for anything that might be wrong with it. I'm a novice and I've got a lot to learn so I guess I should be thankful for the opportunity. Anyway, I checked the thermostat today and, sure enough, it was stuck open. I got it to free up and put it back in. This is the first thing that I've found that was actually not functioning correctly so I'm very hopeful. We'll see - I'm running the boat tomorrow. I'll order a new thermostat and get it shipped down to me as soon as possible.

Thanks to everyone for all the great tips - keep 'em coming.

[IN2DEEP]

Merlin,
I'm glad to help steer you in the right direction.
You can clean up your old thermostat my soaking it in white vinegar and an old toothbrush to remove the salt build up.
Test it in a pot of boiling water and a thermometer and it should be opening at 140 deg.

Keeping the fingers crossed that it cures your problem

Scott

[Occams Razor]

Hello All:

First of all Honda engines are super clean running engines. If they Idle poorly and lope then I would suggest the throttle body cleaning first. Second anything and I mean anything that causes a engine to idle poorly , skip or lope is going to foul the plugs, its inevatable. Plugs have to burn hot at a certain air/fuel ratio to keep the plug clean. This is optimal efficiency. Thermostats will cause over fueling if left unchecked however after any of the repairs take her out and run her rite up for a few minutes and let the fuel clean out the combustion chambers too. Hit it with Chevron fuel treatment too. That will help clean up the back of the intake valves in intake chambers.

[JETTYWOLF]

Dave next time it starts loping try squeezing the bubble and see if it stops .

Could be the High pressure fuel filter.

It's not like a lack of fuel

My mechanic already said it was in need of a tweeking of that adjustment screw you can see behind the fly wheel back where that throttle body (?) is.

Not a huge deal, just does it for a few minutes while warming up, most people wouldn't even notice. Maybe a bit normal, after 8-1000 hrs. ?

I read about it I think in my shop manual, but it doesn't say
1.2.3.4 how to change it that I understand, thats for sure.

[Merlin]

Again, I want to thank everyone for their help and guidance. It looks like that was it - I've run the boat several times now and she continues to purr like a kitten. Although I did a lot of things in the last round the only thing I actually found that was wrong was the thermostat - it was indeed stuck open and I think it was the culprit all along.

I'm super happy to be back on the water with full confidence in my boat and motor. Went fishing yesterday and came home with several nice tuna and dorado!

Hasta!

[welder]

Merlin, VERY happy to hear that , job well done .

Now...................Where are the pictures ?