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I've been told I have a bad ecm, 225. But do I?

B

btravlin2

Regular Contributor
Howdy......this is a continuation of the below topic/thread, but since it is now going in a different direction, I thought I'd start another one.

So I thought it would be straight-forward: replace the coil and plug and go. Not quite. We put another coil and plug in, started the motor, and it was still missing. We ran it only for a minute to make sure. Pulled out the coil and it was hot. We pulled out other coils that were just lukewarm.

The mechanic called a Honda dealer friend and explained the issue. The Honda mechanic said the same thing had happened to him one time. The Honda rep told him to replace the ecm and the problem went away. This is almost a third-person account, and I don't know that it's definitive, so before I replace it I'd like to gather as much feedback as possible.

-Has anyone experienced this?

-Can the ecm be troubleshot and/or repaired?

-are there any tests that can be done with a meter to verify?

-is there anything upstream from the ecm that caused this and can do it again?

-there are 2 ecms listed: one is a "sup" (023) and the other is a "pri" (043). Do I need both or just one?

Help!! Thanks......



http://www.marineengine.com/boat-forum/showthread.php?432725-Anyone-ever-have-a-badly-stuck-coil-on-a-225
 
I can't answer most of your questions and have not had any ECU problems on my 2007 BF 225.

Your ECU should have a sticker on it with the part number and software version.

According to Boats.net ECU 34750-ZY3-023 is obsolete. The current ECU is 34750-ZY3-043 and it cost $891. OUCH!

I know of no way to test the ECU except to eliminate all other possibilities (per Sherlock.) But as you know, there is still a lot about these engines I don't know.

You might search the Internet for a used one, but make sure you have a return guarantee. PayPal would be the the best insurance against getting a bad replacement.
 
I've been all through my Honda shop manual, and nothing about overheated coils that I can find. I also haven't been able to find the spec voltage going to the coils. If I knew that, I thought I could at least test the voltage going to the one that keeps burning up. If that voltage is the same as the other coil voltages, then there would be something else going on.

I think I will try to measure voltage to the coil on my other, good-running motor by removing one wire plug from the coil and using my Fluke to see what the ecm is sending it. And then I'll do the same on my problem coil and compare.

Sound reasonable? I'm just guessing right now.
 
I think I will try to measure voltage to the coil on my other, good-running motor by removing one wire plug from the coil and using my Fluke to see what the ecm is sending it.
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If you've got another 225 can you not put the ecm from the good one onto the other engine and see what happens to the coil?
 
The BF 200 ECU will not work on the BF 225. The ECU for the BF 225 needs to have the VTEC function programmed in.

Had to make a trip today, so had a bit of time to think about this problem. These ECU's seem to be very robust. Over the years few people on this forum have had problems with them.

One off-the-wall thought - is it possible that the spark plug is not seating right or that the seat is scored enough to let hot compressed gases get into the spark plug opening and burn the coil? Related - could a sealing washer from an old spark plug be still in there? I would try to get a magnifying scope in that hole and take a very close look.

Also, have you done a compression test?


Try to eliminate every possibility before forking over $900 for a new ECU.
 
chawk_man said:
One off-the-wall thought - is it possible that the spark plug is not seating right or that the seat is scored enough to let hot compressed gases get into the spark plug opening and burn the coil? Related - could a sealing washer from an old spark plug be still in there? I would try to get a magnifying scope in that hole and take a very close look.
Click to expand...

Good idea. I'll see if I can dig up a scope. But I have other news, as I was able to run over there today.

I popped off all the plug caps going to all the coils on both motors. I tested ohms with no keyed ignition. All were uniform except the cylinder in question. Those readings were crazy off.

Then I keyed the ignition on both motors so that I had passive voltage. I tested on the 12v setting and once again, all were the same except the cyl in question. It was wildly off.

I then called the closest dealer to ask if an ecm from a 200 would work. No, no VTEC. He asked why and I explained. He suggested I chase wires first, before replacing the ecm. Reasonable.

And then metal-chicken suggested the obvious, which I hadn't yet thought of.......take the good ecm and try it on the other motor. I'll do that tomorrow. Clearly, if the motor runs well, then it will be the bad ecm and not the wiring. If it still misses, then......I guess it would have to be the wiring.

Wouldn't it?
 
Before you change the ECM, switch the coil to another cylinder and compare voltage readings again. See if the problem follows the coil or if it stays with the cylinder.

Mike
 
You're right. I forgot you had dual engines. If the fault follows the ECU, you can be pretty sure it's the ECU. However, I'll lay odds it's in the harness, and that's going to be a bugger to track down. Look on page 5-11 of the Helm manual for wire color codes.

Before tearing into the harness, make sure you have a good coil.
 
chawk_man said:
You're right. I forgot you had dual engines. If the fault follows the ECU, you can be pretty sure it's the ECU. However, I'll lay odds it's in the harness, and that's going to be a bugger to track down. Look on page 5-11 of the Helm manual for wire color codes.

Before tearing into the harness, make sure you have a good coil.
Click to expand...

I'm not seeing in the manual how to test a coil. I'm not finding it in Search either. How is it done? I have a Fluke.
 
Well darn. I took the ecm, coil, and sparkplug off the good motor and put them on the other one. Still missing on the #3 cyl. This would seem to identify the wiring as the problem.

The injectors, filters, vst......everything has just been gone thru. I'm out of ideas other than the harness. Rather than fight the existing one, I might spend for a new one. I imagine massive frustration trying to track thru the old one.

Make sense?
 
Did you switch ECU's? Until you do that and the problem DOES NOT follow the ecu to the other engine you cannot be surd whether it's the harness or ecu. If after doing the switch you determine that its the harness, then trace the wiring from the coil as far back toward the ecu as possible looking for broken insulation, burn marks, or pinches. A new harness costs over $500 and it looks like they are a real bugger to replace.
 
chawk_man said:
Did you switch ECU's? Until you do that and the problem DOES NOT follow the ecu to the other engine you cannot be surd whether it's the harness or ecu. If after doing the switch you determine that its the harness, then trace the wiring from the coil as far back toward the ecu as possible looking for broken insulation, burn marks, or pinches. A new harness costs over $500 and it looks like they are a real bugger to replace.
Click to expand...

It's not very hard to replace, pretty much plug n play. If you do decide to replace make sure you put dielectric grease on all connections. Check compression...low compression will cause misfire, I had a personal experience with this and yes I replaced harness thinking it was the problem and it wasn't.
 
Skooter, I have no spark. That has been the issue from the beginning. And the ohm and voltage measurements going to that coil are way off compared to all the other cyls.
 
chawk_man said:
Did you switch ECU's? Until you do that and the problem DOES NOT follow the ecu to the other engine you cannot be surd whether it's the harness or ecu. If after doing the switch you determine that its the harness, then trace the wiring from the coil as far back toward the ecu as possible looking for broken insulation, burn marks, or pinches. A new harness costs over $500 and it looks like they are a real bugger to replace.
Click to expand...

Yes, I switched the ecu/ecm, coil, and SP. All 3 came off the good motor. The only conclusion is the wiring between the ecu and coil is where the issue is, unless there is another possible cause.
 
Yep, I agree. As I said before, trace the wiring from the coil as far back toward the ecu as possible looking for broken insulation, burn marks, or pinches. You might get lucky and save $500.
 
I spoke too soon. It's not the harness. There are two things going on simultaneously: bad ecu and a carboned up cyl......I think.

When I transferred the good components this morning and ran the motor I still had the miss. I assumed that the only thing left was the harness. But I got to thinking....."I didn't actually check for spark. But there couldn't be spark because the motor was missing?! Yes but, just make sure".

So I went back and actually tested for spark with the 3 good components. I have spark.....and a miss. That threw me. But then I thought Skooter is probably right. The cyl might need to be decarbed. The original ecu is bad.

That cyl is the only one that doesn't change the sound of the motor when the plug wire is disconnected, so the problem is in that cyl. And yet there is spark. And the injectors were just professionally cleaned.

I've got a double-dose of RingFree in the tank, but that will take many miles to work through. I know about the Seafoam decarb, but I hate to do it because I just changed the oil, and I use the high dollar Mobil 1. It would annoy me no end to dump that oil.

Any suggestions?
 
First do a compression test. Then a leak down test. It may not be just carboned up. It could be any number of things - blown head gasket, cracked ring, chipped valve, etc. etc. If compression is low, then your first line of repair would be a valve clearance check/reset and then likely be a decarb.
 
chawk_man said:
First do a compression test. Then a leak down test. It may not be just carboned up. It could be any number of things - blown head gasket, cracked ring, chipped valve, etc. etc. If compression is low, then your first line of repair would be a valve clearance check/reset and then likely be a decarb.
Click to expand...


Will do.

Another question. My ecu is 34750-zy3-013. All the parts sites are saying this has been replaced by 34750-zy3-043. Will this be ok with my O2 sensor?
 
I'm not anywhere near my computer so it will take awhile to respond.
If you have Honda SB 70, it sorts that out based on your engine an. Post your sn.
 
I don't know about the ecu. BUT SB 70 says the correct HO2 sensor is 35655-ZY3-013 for your SN (1000001 thru 1309999). That's the one with the 22 mm hex fitting.
 
I have established that the original ecu was bad. I plugged in two good ecu's and have spark to #3 with each one. The original ecu produced no spark and had wild ohm and voltage readings on #3. However, I still have the miss on #3, which should mean that I still don't have combustion in #3.

So yesterday I tried mild decarbing with aerosol Seafoam in the intake. I don't think it was too effective because I didn't see a lot of smoke. But I was just trying to see if some decarbing would get #3 to combust. It didn't.

Here's my question: how can you decarb if the cylinder isn't igniting?

I'm assuming the cyl is heavily carbed up and low on compression, and that's why it's not firing. My mechanic is going to do a compression and leak-down test in the next few days.

My guess is that the previous owner had the motors mounted too low, took in some water, ruined the O2 sensor, didn't change it......making the motor run rich, and with the help of an ecu that wasn't firing the cylinder, carboned up #3. I'm hoping that's all it turns out to be, because I don't want to think about a leaking head gasket, cracked ring, or bad valves.
 
When I did my decarb, my #6 was around 150psi, I ended up tilting motor and pouring seafoam straight into cylinder and let sit overnight. Did this twice and got psi up to 200
 
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