Logo
FULL SITE MENU

Bf 225. Surging

J

Jefferyes

New member
I have read and understood many threads about surging. Most of which include fuel system checks etc.

My engine surged from day 1. Around 3500 rpm. It was subtle but always there. I had occasion the redo the fuel system. But the surging remained.
Over the last twenty years it has reduced somewhat and tends to occur at 3100 rpm.
I just changed the timing belt and now it surges back around 3500 rpm. More like it did twenty years ago
Power and mileage are unchanged. Maybe a tad better now

Any ideas?
 
Hi,

I'm not a seasoned 225 Honda tech. Just an old wrench that is more of an interested "armchair QB" these days. But, you asked for ideas so here's mine:

I don't know what you know so please excuse if I'm going over info or things you've already addressed.

After reading the operations descriptions in the manual, the two major performance components that "adjust" as the engine is running are the VTEC solenoid and the Inlet Air Bypass (IAB) solenoid.

The VTEC activates at 4500 rpm and above and shuts off below that speed. So, I have ruled that out for your hesitation since you say it occurs pretty reliably around 3500 rpm when newer and 3100 rpm as time went by until the recent timing belt replacement.

On the other hand, the IAB solenoid powers on at around 3750 rpm. So, that's close enough to make one wonder if there might be a correlation. But with your experience of the issue changing over the years and occuring at 3100, I have my doubts about the IAB being at fault. Also. I think if it were the IAB, it would likely cause a more notable loss of power over a wider rpm range.

You seem to have covered fuel delivery and, while it's not something I would readily rule out, I think it too would cause more of an issue over a wider rpm range than what you're seeing.

So, my #1 idea about what might cause a slight hesitation at a pretty specific rpm over and over again would be Throttle Position Sensor (TPS).
This sounds like a "bad spot" in the TPS potentiometer.

I would do a "sweep test" of the TPS using an ohmmeter to see if there is a resistance "glitch" as the the throttle is slowly opened and closed.

However, this test, using an ohmmeter, doesn't always yield good information.

A digital ohmmeter might not actually catch and display a fault well enough for you to see it happening. A high quality graphing meter would have an easier to read display but not always. (see below)

I have kept my old analog Micronta (Radio Shack) meter all these years because the sweep hand of the meter is very easy to follow when checking TPS.

But....
...because the event can happen so fast....(multimeters are slow)
....and might not even occur using the meter as the power source....
Most "good" auto shops keep an oscilloscope handy to check components like this "LIVE" while powered by the vehicle to obtain accurate results.

Besides the TPS, other things that come to mind for this would be an oxygen sensor or a MAP sensor.

Hope you find it.

Good luck.







.
 
Welllllll....
I dunno.
You indicated that you've been living with the problem for 20 years so I assume that it's an '02 or'03.

If that's correct, the bad news is that it appears the TPS was only available with the throttle body assembly. A pretty expensive proposition. Looks like about $300 cocos.
And, I say WAS because the throttle body is no longer available for those years.

There may be some used ones somewhere though.

It looks like the '05 would bolt up but you can't assume that it would work. Only a deep dive with Honda engineering would be of any assurance but they might not even know....or care.

But I wouldn't even consider replacing or repairing it without doing at least some rudimentary testing. I could be way off on my guess.
Just Giving My Opinion.

Your call though.

Good luck with it.
 
Yup 2003. One thing I did notice was the throttle cable that closes th throttle was a tad loose. Could that be it?
I didn’t move it or adjust it so it’s been that way for a long time?
 
Oh yeah! I would definitely look into THAT!

Glad you noticed it.

Any "herky-jerky" movement of the throttle linkage might directly effect the way that the throttle body translates movement to the sender as well as disrupt air flow entering the engine. Hopefully, If you can tidy that up, you could solve the hesitation.

Crossed fingers for you.
 
K. Measured up cable gaps. One was off-spec. Two full turns pretty close. Tested out NO Surge.
I wonder it must have been a factory error. One mech did the thermostat recall. Only other work has been plugs oil and filters

Well done diagnosis guys. Thx a bunch
 
Well it was the major recall water getting up into manifolds. 2004 thereabouts. I thought it had something to do with thermostats. Probably got that wrong
 
OK, I know about that one - it's covered in Service Bulletin #56. Water could get up the exhaust tubes and blow the HO2 sensor or worse.

Thanks.
 
Back
Top