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BF135 idling problem ?

S

seiniac

New member
I have a 06 b135. We use it for work so it gets alot of use. Now an ongoing problem is stalling. Starts fine, warms up and when backing off trailer I give it some throttle, when I shift back into neutral it stalls. Usually have to push throttle lever up while cranking to get it started again. During the day when backing off beach with throttle at about 1500 rpm when shiftng back to neutral it either sputters and smoothes out or dies. It idles about 650 rpm which seems a little low. Dealer has been through everything. Hooks up to his computer and runs in test tank. Computer says nothing wrong. Is there any way to adjust idle on these fuel injected engines? Any other thoughts?
 
First off, I have no experience with this engine or any documentation for it either. I do have an extensive background in automotive and heavy truck repair but currently only work on carburetor equipped Hondas. Others here will probably have better information for you. With that said;

Yes, I believe there should be a "base idle" setting adjustment procedure that your dealer probably should have already performed in addressing this issue. Your throttle body does have a "set screw" listed in the parts breakdown and that is what I would think is used to perform base idle setting. And, I agree with you that 650 rpm at idle seems a tad low but, again, I have no documentation to back that statement up. These would be talking points for you and your shop or mechanic.

It's always a good idea to approach an issue like this from the simplest solution and escalate up. So verifying the idle speed is a good idea just as you intuitively concluded. Also, I see from a parts breakdown I looked up on boats.net, there is a filter for the EAC (electronic air control). It might just need cleaning. It is another good point of discussion with your mechanic.

Other things that come to mind that would give you a similar problem and might not log a code are, in no particular order:



Faulty EAC. Sometimes hard to verify without just trying a known good one.

Inlet air temperature sensor or engine coolant temp sensor out of range keeping the computer in the cold start enrichment mode too long and causing fuel "flooding".

Throttle position sensor faulty. Can cause a problem but still be "in range" and fool the computer.

"Lazy" switching oxygen sensor. Not too likely but should be looked at closely.

Map sensor. These are notorious for causing problems and not flagging a code in the computer. However, they usually cause power complaints not idle problems.

Dirty throttle body bore or throttle plate causing air restriction entering the engine at idle. Cleaning with carb spray can sometimes help although it could also void a warranty as special coatings used on these surfaces (usually teflon) can be affected by too strong a chemical. Use caution here.

Faulty knock sensor. As engine transitions from off idle to idle, harmonics could be causing the sensor to retard timing. Pretty unlikely but you never know.

This appears to be a COP engine. Meaning "coil over plug". These are common in the automotive world today but can exhibit problems with the ignition system that can be hard to diagnose. I hope your problem is a simple fuel ratio problem and not a complicated electronic issue.

Good luck.
 
Idle speed in neutral should be 750 plus/minus 50 rpm
Trolling speed (motor just put into gear and no additional throttle) should be 650 plus/minus 50 rpm

Just a few things off the top of my head to look at...may be repetitive from jimmyd...

If you are going to try to clean the throttle body, spray your solvent on a rag (do not spray into the throttle body) and wipe everything clean. It may have a lot of dirt and black deposits if you are using this at slower speeds.

There is a map sensor on the top of the throttle body. Remove it (one screw) and clean out the little passage in the throttle body.

Also, right where the throttle body connects to the intake manifold (big black plastic piece that covers most of the side of the engine...there is a electronic air control. Two bolts hold it one. Under where it attaches to the intake manifold, there is a very small screen that can get clogged up. Clean out the screen with solvent (I generally used something not too toxic like brake clean) and make sure the passage to the intake manifold is clean. Having to advance the throttle to start the engine, could be caused by any of the above. You are doing what the electronic air control is supposed to do on its own.

To adjust the idle, the motor needs to be in the service mode. Do these things and check the things that jimmyd suggested before you start tinkering with the idle. I have never had to adjust one. We service some 150's (same basic engine as the 135) with a couple thousand hours on them and they still purr like they did when we first put them on. Of course, they are serviced every 100 hours (sometimes more frequently).

Mike
 
Thanks guys. I remember cleaning that little screen once before. I will try all of the above and see what happens. My service guy gave me a copy of section of service manual that shows adjusting idle but I don't think I want to go through all that. We do routine maint. as required (every 50 hrs, 100hrs, etc.) engine now at 1500 hrs. I did change the thermostats, they don't seem to hold up long in salt water. Thankfully so far when they do stick, they stick open.
 
Did all that you suggested. When I removed the black plastic housing where air passes from top of engine into throttle body it had oil residue in it. Cleaned it thouroughly. Cleaned throttle body (not too dirty), removed MAP sensor and made sure all was good and clean, and removed EAC and cleaned screen (kind of dirty and carboned). Started in shop with earmuffs and seems to be OK. Won't know for sure till I get it back on the water. Thanks for the advice!
Wondering why I have oil in air cleaner thing? Also seems to have a lot of black soot on lower cowling below exhaust port.
 
Some oil residue in the "muffler" housing could be a normal condition as that is where the crankcase pressure is vented. You will notice a hose running from the valve cover to that box and that is the crankcase vent.

Excessive amounts of oil or puddles of engine oil in that housing could indicate excessive crankcase pressure due to cylinder and piston ring wear or someone over filling the crankcase with oil. If the oil level is correct and there is no "liquid" there, I wouldn't worry about it if the engine is running satisfactorily.

Additionally, given your apparent air starvation at idle due to the dirty EAC screen, it may not be unusual to see soot at that exhaust port due to an overly rich idle mixture. Again, I wouldn't be too concerned with either of these indicators on a well used engine but, of course, it's always a good idea to keep a weather eye out on these things.
 
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