Fried ECU again, reasons???

Ok, so in April at the track day at Spa-Francorchamps, my VFR fried the original ECU from late 1995. I replaced it with one from eBay, and now that one is fried as well. Does anyine here have any ideas as to what would be killing ECU's on my VFR? This is an issue that I'd really like to sort out, as I don't want to keep throwing ECU's at her, just for her to eat them on a regular basis. Any ideas would be helpful, as I have my own theories, but am not sure how sound they are. Thanks!

 

Well let us hear them first. You might just have the answer and don't know it. Besides we don't laff that hard................:cheersaf:

 

Several things kill electronic circuit boards....


#1: Heat.
#2: Vibration
#3 bad power/ground
#4 Old age and treachery
#5 Hard shorts on input leads that are not designed for a hard short.
#6 overvoltage on a signal input.



So, whens the last time you checked you Rectifier/regulator? Grounds in good shape? aftermarket rerouted exhaust? Your gonna need a good voltmeter.



As much as I hate to spend the money on new I never buy used ECM's....(old age and treachery.)

 

If you was a womern i'd say to let an electrician check your shorts...

the ECU doesn't control injection since we have carburetors, only the sparking coils, but them ECUs make for expensive fuses.

Have you done any mods on your racin bike that involved any electricals stuff--like a kill switch on the shifter, etc.?

let's hear your theoreticals too, you know more about what it's doing than anyone.

 

Ok, I do have a complete after market exhaust, it was installed last year. I also spliced in a set of CBR 1000RR gauges, but that was done several years ago. I fitted the RC-51 tail section several years ago as well, and changed the original location of the ECU from stock, but again, it's been that way for several years, so I'm not sure why it killed two now within a four month period. No kill switch, or anything else like that, I did install a gear position indicator though, but that's an easy install, and that was also installed about two years ago. I was thinking that either somehow it was getting over voltage, but wouldn't know where, as I'd imagine that there would be some sort of diode or shunt in-line with the ECU to prevent that from happening. I'm not sure how a bad ground could kill an ECU, but I'm not very electrically savvy. I do have a newer R/R, and the upgraded R/R wiring harness, and thaose were also installed a few years ago as well. This is really frustrating, as I was planning to get my engine rebuilt this winter in Holland, but if I can't get this issue sorted, I'm not sure if that would be a wise thing to do.

 

Your r/r might be allowing excess voltage into the system cuz it's getting weird.

 

Basically what happens is when I turn the key on, and depress the start button, the bike tries to fire, but won't start. fuel and air is good, not getting any spark to the plugs. The manual has me check the side stand switch, the pulse generator, and a few other things finally getting it down to the ECU. Just like last time, the bike started running rough, like it was mis-firing really bad, on 3 cylinders, then it just wouldn't start. I may have a bad coil, and that could be killing the ECU, but I'm not 100% sure about that, as there isn't a way that I can check my coils out now, as they're not getting a signal to fire from the ECU.

 

I am very interested in these. Let me check mine to ensure that it is the coils that are bad, and I'll get back toi you. May take me a few days to respond though, as I've been uncomfortably busy lately, and could use a few more hours in the day! Thanks!

 

there are 2 circuits on most coils, low voltage and high voltage side. On a voltmeter you should see low ohms on both but NOT a direct short AND both circuits should be OPEN to EACH OTHER.

Most coils ground on the mount tab on frame screw.

 

Find the problem yet?

 

I have not, and am still trouble shooting, as everything (pulse generator, cols, switches) have all checked good.
This is what I found...The ignition pulse genetator coil at the ECU/ICM plug is supposed to read between 450-550 ohms, mine is reading 313 ohms. All four coils are withing spec and are reading 3 ohms. The spark plug caps are also within spec reading a solid 19 ohms. The pulse generator readings at the black plug at the pulse generator end was reading 312 ohms if I remember right, regardless it was within spec. The only things not checked were the side stand switch, and the neutral switch, as my wiring is pretty much disconnected right now. I'm running out of things to check, and I'm still curious as to why I'm only getting 313 ohms at the ICM/ECU plug for the pulse generator, when it checks good at the other end.

 

Are the plugs fouled?

If the starter motor is turning over then all the fuses, switches and interlocks (side stand, neutral, clutch diode) associated with the ignition have to be functionally okay, otherwise no cranky.

Is the fuel pump actually pumping? If it is then the ECU/ICM and the pulse generator is working okay and the fuel cut relay is working okay also, since the ICM fires coil #4 and the fuel cut relay on the same line. If it's not then pulse generator, fuel cut relay and ICM are suspects.

One side of the coils is +12 volts all the time, the other coil terminal goes back to the ICM and pulses between +12 and ground. A voltmeter can be used to detect if this pulsing occurs when you push the starter button. If it is pulsing then the pulse generator and ICM is working okay and the spark plugs are fouled.

Has the bike set up such that the carbs are dumping fuel down the intake/ float valve not cutting off?

 

I get a strong fuel smell when cranking the bike, but no spark. I think I may have a bad ground somewhere in the wiring harness, as when I was doing some troubleshooting on it the other day, the left head light wouldn't come on low beam, but would work on high beam, and the filament was good, same issue when replaced with the right light bulb, as I knew that was a good bulb. Also tail lights are inop. Brake lights work, but no tail lights.

 

What do the spark plugs look like--are the plugs wet?

The headlights share the same power feed and ground return lines, as do the tail and brake lights, so that issue sounds like oxidized terminal contacts/spade lugs in the connectors--if the ground weren't connected then both left and right would be affected. But it is worth tracing the ground from the battery to the frame to ensure good continuity.

Has the bike been dropped or wrecked or other incident on the track that may have cut into wiring or dislodged the pulse generator?

 

I don't remember the plugs being wet, but to be honest, I wasn't really looking at that as a potential cause. As far as coloring, they looked just fine, not running rich, or lean. I haven't dropped the bike in the 10 years that I've owned it, but prior to that, I can't be certain. I plan on changing out the wiring harness this weekend, with a different one.

 

If the plugs are wet it won't start.

 

Ok, so as far as I can tell my ECU isn't fried, I just had the kill switch on, DUH!!! Anyway I am still having fueling or ignition issues, but should have that worked out shortly, as I'm replacing suspect parts. Never experienced a bike that would try to crank with the kill switch engaged, that's a new one to me!