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2003 Honda 200 rpm reduction and alarm

H

hurricane

New member
Hi, This is the second shot at a previous post that is still driving me nuts. When the motor reaches temp and there is a quick acceleration, the alarm will sound (constant) and motor will go into a rpm reduction- green oil light off. I have narrowed it down to the oil "high" sensor and replaced it to no avail. If you disconnect this sensor after the motor has started then there's no problem. You can't leave it disconnected because on the next start it will leave a fault and sound alternating beep. Does anyone know how this sensor works? is it temperature? pressure? thanks
 
How do you disconnect the oil high sensor when the engine is running? I thought you have to take off the intake manifold to get to it. I am confused....

To answer your question, it operates based on oil pressure.
 
I have not had any experience with problems with the high pressure sensor. The good news is, I have not had a lot of issues with the 200/225's that we service.

I have had experience with the low oil pressure switch, when there was a clog in the oil pickup tube.

I noticed on a previous post, you measured the oil pressure when you rev'd it at about 60 psi. The normal oil pressure at idle is supposed to be about 17 -26 psi. If you have a manual, you probably already know that.

The HDS manual explains that the high switch is sensing the oil pressure to be sure it is sufficient above 3000 rpm. That means to me that the switch is closed at startup but then opens with good oil pressure. When you disconnect it, it is still an open circuit. If the oil pressure stays good the whole time, the circuit would normally stay open. It probably sets a code when you do not reconnect it for the next startup, because the ECM is probably looking for no oil pressure at initial start. I may be a little off on the timing of when the ECM is looking at it during key on, etc.

Where did you measure the oil pressure? Did you measure it at the 3/4 to 1 inch sealing bolt plug at the top of the starboard side of the motor behind the wiring harness? It has a square hole about 3/8" in it for a wrench. I am not sure if it matters but it might.

Also, did you examine the opening where the switch goes for any debris that might clog the switch? Thus causing low oil pressure reading sometimes.

I remember when I had the low pressure problem, that there was not very good documentation on the flow of the oil.

This may sound crazy, but I wonder if you could have a blockage somewhere after where you measured the pressure and before the switch and the oil pan? That might account for the high pressure but leave low pressure at the switch. That is only a hypothosis. Unfortunately, I do not know where is the course of flow everything is.

There is one place you might check and clean, that is easy to get to and is definitely in the oil path...

There is a small filter (spool valve filter) that is located just adjacent to the sealing bolt (where the oil pressure should be checked - top starboard side of the engine). It is where the VTEC valve is on the 225 HP but it is a dummy spool valve on the 200 HP. There is still a small wire mesh filter there. Its cover is held on by three bolts I think. If it has any debris on it, it could be restricting some flow above 3000 rpm.

At least through all this rambling, there is something to check.

One other thought (although obvious), while we are on filters...have you changed your oil filter lately and is it the official Honda filter and not an aftermarket brand? Have you checked the openings at the oil filter for any partial blockages?

I do not remember if you had anyone put an HDS on this to see what the ecm is seeing from the switches....Bottom line, I guess, if your oil pressure is acutally good (no restrictions) and the switches are sending out the proper indication at low and high rpm, then the ECM or connections to the ECM may have issues.

I know I may be going down a path that is different from where you may have been, but it is the only thing coming to mind.

I hope the filter is partially clogged.

Mike
 
Hey thanks Mike! The oil pressure at idle was as low as 8psi when hot. It was measured at the top strbd plate (where the manual tells you to). The filter is new but I will check the other filter you mentioned. Again, the only issue is mid to top end. What was occuring when you had the low oil pressure issue? I'm going to try the old sender for a start up and then close the circuit- if the horn goes again at least I'll know it isn't oil pressure related. thanks again
 
I am not sure what you mean by close the circuit.

At initial startup, I think the circuit is closed by the senser, then it opens when there is good pressure. I think when you close the circuit, and rev over 3000 rpm, you will get an alarm, if I am understanding the workings correctly.

My low oil pressure issue was caused by somehow, the customer unknowingly, got a paper like substance in the oil system. I think it may have been from the seals on the quart bottles of oil that he was using that he put into the oil fill. They must have dropped in. They went all the way to the oil pan and got sucked up into the oil pickup tube. There was a screen there and it was almost totally blocked.
When I checked the oil pressure, it confirmed that there was a problem. Pretty straight forward. I just had to start tearing things down until I found the clog.

That is why I am thinking you have a partial blockage some place. But your oil pressure readings do not back that up. So I am puzzled.

The sensor is checking for fuel pressure at high rpm. So, either the sensor is bad (you just changed it), the oil pressure goes low above 3000 rpm, the wiring in the harness from the sensor to the ECM is temporariy shorting or a ground is being applied to the wire going from the sensor, or bad ecm.

This is rather puzzling..

Mike
 
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