2006 Honda BF 150's port motor shakes at idle

Hi guys, I am new to the forum but have looked for many years. Thanks for all the input.

I have a pair of Honda bf 150's 2006 they have always run and performed well, they are on my 26 SeaVee center console and I charter out of Cape Cod, Mass.

The motors were purchased new and I now have 2400hrs on them, they run 5600RPM's WOT with a load on the boat. The only alarm I have ever had was a couple of overheat's and the eel grass here was the problem stop back up and fine. Every spring I do all fuel filters, plugs, thermos, clean IAS screens, zincs, drain VST tanks, water pumps and more recently changed the screen under the HP fuel pump's. I have never had any fuel related problems with this setup.

From about 200hrs on, the port motor has started to stall when warm. It is usually random but now has got worse. When flushing on the muffs the port motor runs fine for 10 seconds or so then rpm's drop and it starts to sputter and shake bad. If I turn it off it restarts fine but the same thing happens.

I have read Hornblower's thread SCS codes and it seems as he was having the exact same problem I have. I have done the same thing as him to try to isolate the problem swapping sensors, fuel rails, ECM's, IAC's, Map's, O/2's checked all plugs for loose connections. If I unplug my A/F sensor the motor runs better and smooth but I think that is because the rpm's are up at 850 and it cleans up the stumble.

On the advise of Honda American I checked the crank shaft end play for the thrush bearing problem and they both are tight and well within spec. Compression was even and where they need to be. Drop test was good as well. I run ring free a few times a year and this spring did Dunks method of decarb. When the stumble occurs if I squeeze the primer ball it gets hard and does not change the motor's stumble.

I think the only thing left to do is a valve check but that will have to wait till the end of my fishing season.

I was hoping that someone could give me there thoughts as it's driving me crazy. The motors run great except at idle and stall

Thanks in advance for any input on this...

Josh

Outermost Angling Charters

Looking for input please.. Hondadude, Hornblower anybody.

Thanks

J

Did you clean the throttle body ? Idle air by pass screw ? seems to be you did lot of things,i have seen same problems with BF150 ,Honda japan say some problems with valve seats but i don't understand it, coz no any problem except rough idle. adjust valve clearance and try.

wajira

Hi Josh,
I'm sure you want to hear from hondadude on this but I thought I would just throw this at you:

Did you swap the temperature sensors between engines? The engine temp sensor and the inlet air sensor have a lot to do with idle function. If either one is skewed just a bit...it could cause symptoms.

Also, if your throttle body is hanging up and not fully closing (usually dirt) it can cause idle issues. But you do have to be careful when cleaning one due to the fact that they are calibrated and most are built with a slippery coating to keep dirt from sticking. If you try to clean yours...I would...use a mild cleaner like WD 40 or purchase one of the new Throttle Body Cleaners that are now being sold in the automotive stores. You DO NOT want to wipe off the coating OR nick or damage the throttle bore or plate in any way.

This could also be a vacuum leak that has developed. As things heat up they expand...we all know that. It could be that as the materials of your intake system expand a leak is occurring. One way to check for this is to use a hand held PROPANE soldering torch to introduce UNLIT gas in and around the intake system. If the gas encounters an opening to enter the intake, the engine will speed up due to the artificial enrichment. That can pinpoint the leak. It is effective and it is safe if reasonable precautions are taken.

Another thought I had is that you may just need more decarb. I like to use WATER. Spritzed into the air inlet at about 2,000rpm. Very effective and cheap. Although...if carbon build up was the problem...I would think the other engine might need treatment as well....seeing as how they are both operated in EXACTLY the same manner.

Hope you get better answers than mine and GOOD LUCK!

Wajira, thanks for the input.

My motors tend to push a little oil back into the air box from the valve cover vent line. I always wondered if that could effect idle problems. I did clean out the air box last year along with cleaning the throttle body being careful not to scratch anything. I used a clean rag as to not disturb the coating that is in the throttle body itself. I will check valve lash and see where they are at. Where is the idle bypass screw? and how would I clean or adjust that. Thanks..

Jgmo,

Thanks for the help.. I did not swap those and I will ASAP. Is the temp sensor just in front of the O/2 censor? and the inlet air sensor is in the front of the air box I think. I will look them up on Boats.net and see the location, man there is a lot of sensors on these little four bangers.

I will try the propane trick for a vacuum leak. I did try with spraying carp cleaned around the vacuum lines and intake to see if I could get a rise in idle but it stayed steady.

I always wondered about temp sensors just like the o/2 censors giving the computer false temp reading and leaning or fattening the mixture and making the motor stumble as the air/fuel mix would be off.

Other than at idle the motors run very well at all RPM's under load.

We are having a NE blow with rain at the moment on the East coast with a hurricane looming offshore. When the rain stops I will report back my findings.

Thanks so much for reading my post and giving me advice on how to fix it.

Josh

Jgmo,

On boats.net I looked up the air temp sensor its honda part number 37880-PLC-004 its in the front of the air box, is this the one that you are talking about?

Also it looks like 3 water temp sensors one in the top back of the exhaust manifold and two in the thermostat housing should I swap all 3 of them and are these the ones you talked about.

Thanks in advance
Josh

Yes, the one in the air box is the one for INLET AIR TEMP...IAT.

The other three I would have to look up. But...for fuel control they would probably use the one that gave the most info...that might be a 3 wire sensor. The other two will likely be used for overtemp. I'm GUESSING here but I think it will be one of the sensors in the TStat housing. You could just swap those two, if feasible, and see if it makes a difference.

Hopefully Mike will chime in as soon as he gets a chance.

I read Wajira's post and I sure hope you don't have any valve seat issues. That can be hard to diagnose and costly to repair.

One other thought is this:

The computer (ECM) is programmed to be "parameter adaptive"...meaning: As the values of some of the components change over time IE: MAP and O2 sensors primarily....along with engine wear....IE: cam lobes...valve setting...injector coil resistance and fuel flow... and so on....

...the program "adjusts" to allow for such changes and wear taking place. This gives the engine a set of numbers it can "hit" and still be considered "in the ballpark" of performance and fuel efficiency. Sort of like putting the gutter balloons in the bowling alley for the kids. It keeps the engine running optimally for varied conditions over a longer period of time.

BUT...when swapping parts as you have been doing....the ECM doesn't KNOW it is working with a new set of components RIGHT AWAY. It will operate off of the last input it received at the last ignition cycle. As a result...swapping parts might not show ANY differences IMMEDIATELY. It might take a while for the ECM to "adjust" to the new input.

If you had the HDS...I believe that you could actually reset the ECM for just this type of thing. And, on many automobiles I know that discharging the capacitors in the computer will do the same thing. This is done by taking the battery cables off and touching them together for a few minutes. You hook the battery back up and the ECM is back to "day one..hour one". It's called a "parameter reset" in FORD speak. I'm not sure if Honda works the same way but it might be something to consider.

Stay Dry!

Thanks so much for your informative and helpful answers.

I will switch those sensors and see what happens.

Do you think I could have the ECm's reset or reflashed and would this even help with sensor problems. I could remove them and take them to the shop and have this done. I googled your Ford parameter reset for Hondas but can't find any feedback about connecting battery leads for 10 minutes to clear or reset Ecm.

I might try to switch those sensors, IAT and temp and run the boat for a day or two and see if anything changes.

Josh

The 2006 ECM's can not be reflashed (as far as I know). Connecting the battery cables together also does nothing, as far as I know. All you can do is clear the codes, which you can do via the stop switch. I doubt if it will do anything....but stranger things have happened.

I can not say I remember everything that you did, but since you can not check valves now, I would do the basics that have been mentioned and maybe a couple of other things.

-Clean the throttle body.
-Blow any dust etc out of the map (on the throttle body)....you might even try switching it with the other motor. Make sure the opening in the throttle body is clean and clear of debris.
-Clean the IAC screen. If you have not switched the IAC, I would do so. If your IAC is only working slightly, it will not be able to control your idling ....it basically has very little affect at high speed.
-Make sure you oil level is 1/4" below full mark.
-I think you said you did a cylinder drop test, but you could have a misfiring spark plug. Change those, if you have not already. If that does not fix it, then you have a spare set of plugs. Only use the NGK's.
-You mentioned you run Ring Free every so often. Now might be a good time to do a concentrated treatment using a small fuel tank and really give it the gusto.
-If you have a hand held temp gun, check the temperature of the engine at the thermostats and make sure it is really getting to temperature.

This kind of problem is hard enough to fix using Dr. H, where we can see what the ECM is looking at from the sensors. You are working with one arm tied behind your back. All we can really suggest are common things that may affect the idle.

I hope the wind does not give you too much trouble. Hang in there.

Mike
-

I think Mike's "check the temperature" could be your "magic bullet"...it's one of the "basics" I just flat out "air balled" when I was trying to come up with solutions. "OF COURSE!" I thought when I read his post....even though you replace the stats every season...you could get one that is "sticky" and won't let the engine come up to temp. Check that asap!

Sorry to get your hopes up about the reset but....all computers have capacitors and what is called "memory". It will not harm your ECM in ANY way to take the battery cables off and touch them together for a few minutes. So...if all else fails....you could still try it.

Good luck!

Guys thanks, I will keep working at it.

Quick question would the map sensor or that IAT sensor in the air box if bad or out of spec create this idle stumble. If either was bad would the HDS pick it up.

I cleaned both air boxes and as I said above these motors like to push a little oil out the CC vent and puts it down at the TBoby. I switched these sensors and seems like the other one has started to stumble a little. The port still does it bad but wonder like jgmo stated above that it could take some time before the computer recognizes the new sensor or swapped sensor.

jgmo, the temp sensor in the manifold top is the four wire the tstats have two wires. Can you tell me if those are o-ring seals or do they need some honda bond on them if I switch them.

Mike,

Thanks for your input, Should I check it hot or on startup and monitor as it warms up. I guessing but 165* hot or more I will check it out.

Thanks
Josh

Testing...testing....having trouble with the site letting me post....testing....testing.

Josh,
I've tried twice now to answer you and the site keeps killing my post. I think it is a "time" issue. Sorry..I just can't type fast enough for them I guess....maybe later.
Sorry.

Trying again....Mike is your "go to" guy for specifics. I don't have the manual for your outboard. He may be able to tell you which of the temperature sensors are dedicated to fuel control.

I did however look at the parts pages and it looks as if the coolant sensors in the TSTAT housing use Orings. Just make sure you don't over tighten them and "squeeze" them out of shape.

Looking at the intake manifold page (link below) there is a "valve" and an "electronic control" associated with incoming air. The electronic control is the IAC...have you cleaned the "filter" or screen that is under it" (item #19). If not, do so.

I'm not sure about that "valve" and that would be something Mike might tell us all about.

Also, on that same page...refer to item #5. The fuel pressure regulator or FPR. I would like to have you run the engine until warm and, after shut down, pull the vacuum control line off of the nipple on the regulator. You should NOT see any moisture in that line or in the nipple of the regulator. If you see gasoline in there it means that the regulator has a failed diaphragm and will need to be replaced. This is just a fuel injection 101 check for this symptom and I apologize for not mentioning it sooner. Been out of the biz too long.

http://www.boats.net/parts/search/H...F150A6 XA/INTAKE MANIFOLD INJECTOR/parts.html

Thanks for the help.
I clean the screen IAC ever year as it gets dirty. I have checked them again and swapped them no change. I will check that FPR and look for the gas droplets. I might take it in and get the codes read althought its never thrown any that I know of. Just me swapping stuff and making sure alarms will trigger if I pull the sensor plug. I started thinking o2 sensor but I still get good fuel mileage. Man I know its something stupid Ive checked vacume. I really believe its something between a sensor or sensors fattening or leaning the mix at idle. On cold start the port motor after 10 seconds or so drops Rpms and stumbles right away. The starboard motor on cold start idles up at 850 and as it warms up the Rpms drop very steady and smoothly to 760 and idle is consistent. Not a lot of good honda gurus out here. I will keep trying and hope to nail it so we can help others.


Thanks for you advise.

Josh

I will check temp with a gun just have to borrow one. I think that's a good idea as try to check fuel pressure but as the motor stumbles I pump the primer Bulb and that does nothing to clean it up.

J

The thermostats fully open at 140 deg F for the head and 158 deg F for the block. The rough idle is probably not due to low temperatures, but it would be good to see that the motor is coming to temperature.

The squeeze bulb only fills the vapor separator and primes the low pressure fuel pump. So, if there is no change when you squeeze the bulb, it only indicates that the low pressure fuel pump is probably doing what it should do.

The high pressure fuel pump in the vapor separator provides the pressurized fuel for the injectors. That would be a good pressure to check. Should be around 40 - 45 psi.

The air control device that Jimmy is referring to is the Intake Air Bypass. It should be closed at low speeds. It opens up at higher speeds to allow more air.

I am not sure which temperature sensors do what other than measuring specific parts of the engine. I do not know which would have most effect on the idle. The ect's have o rings, that are supposed to be changed when replacing them.

If you can get it to a dealer, the HDS would be able to indicate what might be out of range (but not enough to throw a code).

Keep in mind that the HDS will not directly identify problems with fuel pressure or valve clearances....which are two things that you have still not checked.

Mike

Did you ever find out the issue? I have the exact same issue happening with one of my bf150s and have been through the same steps that have been posted with no resolution yet.