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2006 Honda Bf225 rough/sputter/misfire at idle

J

JayfromNH

New member
Hey all, have been reading this forum for a while now. I have an 06 225 and have been having idle issues for a while now. Sometimes it will idle smoothly, but randomly will start shaking and sputter. Almost sounds like it’s misfiring. Similar noise to how a car with a big cam sounds, loping. It runs like a top at high rpm, no issues yet.

Things I have done: replaced HP, LP filters, and fuel water separator in boat. Cleaned IAC valve. Cleaned MAP and IAT sensors. Checked plugs. Pump primer bulb when it acts up (no change). Drained the VST while pumping bulb. New thermostats and water pump. Nothing has really solved this. No alarms ever.

Seems like a needle in a haystack. Could be valve adjustment, or VST HP fuel screen, or bad coil, or bad fuel line or bad O2 sensor. I’d rather troubleshoot the issue one by one instead of just throwing parts at it.

What would you check next? Does everyone’s run crappy at idle? It’s not that big of a deal as it doesn’t stall, but I don’t want to wait until it starts giving me real issues to figure this out. Thanks in advance!
 
Hi,
I don't work on these but am thinking I might try removing and clearing the throttle body.

If the throttle blade or air passage gets dirty, it could cause it to stop at various positions when at idle and that could cause the TPS counts (resistance) to change and be inconsistent.

Use throttle body spray cleaner ONLY and use caution about handling it because they are no longer available new. No scrubbing with anything more coarse than a soft toothbrush. NO OOPSY DROPPSY! Use great care and accuracy when handling and, plugging in the electrical connectors.


While there, check out the flame trap screen and clean if needed. Item 6 in the link

Also in that area are the tubes for the crankcase breather system. Items 28, 29, 30 in link below

Make sure they're all properly connected and secure with no holes or cracks


Good luck.
 
I totally agree with JGMO on that advice.

I think that if the screen on the bottom of the HP pump holder was clogged, you would have problems at higher RPM's.

A bad plug, coil or HO2 sensor you give you a code 1. Maybe pull codes. 2 documents attached - the proper way to pull codes, and what the codes mean.

Another possibility is that the intake IAB (intake air bypass) is intermittently sticking open. To test that, see the third attached document I wrote up several years ago - the first 5 paragraphs.

One final (a bit off the wall) thing comes to mind is that maybe your LP fuel pump is malfunctioning.
 

Attachments

  • Procedure for Getting Fault Codes.pdf
    189.6 KB · Views: 4
  • MIL Fault Codes Scanned.pdf
    85.1 KB · Views: 9
  • Honda 225 Intake Air Bypass.pdf
    451.4 KB · Views: 7
chawk_man said:
I totally agree with JGMO on that advice.

I think that if the screen on the bottom of the HP pump holder was clogged, you would have problems at higher RPM's.

A bad plug, coil or HO2 sensor you give you a code 1. Maybe pull codes. 2 documents attached - the proper way to pull codes, and what the codes mean.

Another possibility is that the intake IAB (intake air bypass) is intermittently sticking open. To test that, see the third attached document I wrote up several years ago - the first 5 paragraphs.

One final (a bit off the wall) thing comes to mind is that maybe your LP fuel pump is malfunctioning.
Click to expand...
If I had an active fault, I was under the impression the buzzer would sound each time it’s started? (Separate from initial ‘key is on’ buzzer) Other issue I need to fix to pull codes is that ALL of my lights including the MIL have burnt bulbs… which I just found the right parts diagram for yesterday. On their way.

Funny enough, I had seen your post already on IAB, so I checked mine and luckily she moves well! Lubed it up while I was in there!


JGMO, great advice. Actually, before the season I had taken off the entire air box and that flame screen was mostly fine, cleaned it anyways. BUT I did notice my throttle body was filthy and gave it a good wipe, but didn’t take it off for a full cleaning. I’ll give that a shot next.

When I went to clean the IAC, the screen was completely plugged with junk. So much so, that it was sucked inward toward the throttle body from how blocked up it was. Thought that was going to be the smoking gun fix!! Cleaned that very well and the valve/ solenoid seems to be functioning per multimeter test.

Also, per the service manual for adjusting idle, i unplugged it, alarm came on, but the engine died almost right away (manual says rpm should just drop lower, not die completely). And when I give it a bit of throttle slowly, I can still hear secondary air being pulled through that IAC. When’s that solenoid supposed to snap shut?
 
I don't know specifically but I believe the ECM should be closing the IAC as soon as it sees the TPS counts rise from base idle. The IAC can be damaged if manipulated manually. Hopefully that hasn't happened.

From what you say about the IAC being so dirty, it.sounds to me like there could be some gunk/debris floating around inside the bypass passage or stuck to the tip of the idle adjusting screw. If that passage gets restricted, even a little, it will cause the idle to go low.

Conversely, an air leak from a damaged passage will cause the idle to be too high.

Bottoming out the adjustment screw can deform the bypass seat and/or the tip of the screw. That could result in an erratic idle that can't be properly adjusted.

This throttle body may tolerate small, gentle, manual movements of the throttle valve/plate but they are easily damaged from being handled like that. If the blade is opened and accidentally slips and snaps closed, damage can occur. Even wiping/cleaning too aggressively with a soft cloth is advised against so be very careful with it. Finding a replacement might be difficult and expensive.
 
jgmo said:
I don't know specifically but I believe the ECM should be closing the IAC as soon as it sees the TPS counts rise from base idle. The IAC can be damaged if manipulated manually. Hopefully that hasn't happened.

From what you say about the IAC being so dirty, it.sounds to me like there could be some gunk/debris floating around inside the bypass passage or stuck to the tip of the idle adjusting screw. If that passage gets restricted, even a little, it will cause the idle to go low.

Conversely, an air leak from a damaged passage will cause the idle to be too high.

Bottoming out the adjustment screw can deform the bypass seat and/or the tip of the screw. That could result in an erratic idle that can't be properly adjusted.

This throttle body may tolerate small, gentle, manual movements of the throttle valve/plate but they are easily damaged from being handled like that. If the blade is opened and accidentally slips and snaps closed, damage can occur. Even wiping/cleaning too aggressively with a soft cloth is advised against so be very careful with it. Finding a replacement might be difficult and expensive.
Click to expand...
Good advice, I’ll give the throttle body a good cleaning and check those things out. Sounds like I gotta be more gentle with it too…
 
Jay, I am having the same problem. My engine stalls right after start. If I rev my engine up, then it will run fine. I cleaned the IAT screen and it "resolved" the stalling issue. Now it idles rough and stalls once a while. It runs fine once I get it to run. I was going to continue my fishing season, but my wife wants me to get my boat "fixed". Finally I got my trailer fixed and ready to pull my boat out. I am going to try what Jay have done and see if that will resolve the rough idling issue. Wish me luck.
 
I’ll keep this post updated as I troubleshoot things throughout this next week.

Also fighting a sluggish starting issue.. very odd. Brand new batteries, newer starter within the last few years. Happens at random haven’t noticed a pattern yet, but occasionally when I go to start it, it will barely turnover for the first second or so then while holding the key there it will get moving but still very slowly. Did a voltage drop test on the ground side, from starter ground to battery ground to check if the cable or connections have some resistance, and saw 2V drop which is way WAY higher than it should be, but also seemingly impossible for the starter to even turn at that low of a voltage. But the odd thing to me was I saw the same exact reading when testing the positive side. My battery switch is super super stiff to turn so I’m gonna replace that anyways.. hopefully maybe it’s just that.
 
I've had a similar issue with my 07 bf225. Sprayed electrical contact fluid in every place I could get too, then with battery disconnected, turned the selector switch it's various positions at least a dozen times. Problem solved. Probably just dirty contacts.
 
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