Two TCI in one week ?.

[mmaleney]

Last week i was out on my 87 venture when the bike started to backfire and loose power, made it home OK and checking things out found the TCI was bad so put in a spare all good bike ran fine. About a day or so out on the bike again it started to run rough again not like before this time #2 cylinder went out,got home again OK, put in a old 83 mark TCI I had good enough to start the motor on, bike ran on all 4 cylinders again.

 

I checked for voltage to see if that was high bike checked out at 14.2 at 3000 RPM.

 

I don't want to put one more TCI in there and have it go out again so is there anything more I can check?.

 

And I know that it may just be one of those things that two 30 year old TCI boxes went out in one week. But maybe not.

 

Thanks.

[Patch]

Did I miss your post regarding the first decision to change the TCI? Could you link it here please..

 

I'd like to understand how it started and what you noticed that lead to the TCI, with some details.

 

First thing I thought of was coils. The TCI is a protected circuit at the moments the sheets aren't in front of me... These coils are around 1.5 ohms if memory serves, which is not what I would have thought would be a chosen value but, suggests that Yam had confidence in there protection design!

 

So what can go wrong? Like I said I like to mull it over a bit but/ if you are not discharging to ground the it is conceivable that one or more coils are discharging thru the primary!

 

So coil readings may point us somewhere, volts, ohms on both primary and secondary.

 

Then a close look at the harnesses to and from the TCI would serve you well. This could mean a pin to pin resistance but also a pin to each pin, maybe I'll leave it to Bongo to explain that testing if you aren't following what I mean by...

Short between wires in same harness..

[Flyinfool]

2 TCIs in a week does raise an eyebrow and get a HUH!

 

Unfortunately there is no test for the TCI, I am sure that Yamaha once had a tester but I have never seen one or heard of one that someone had. It is a matter of eliminate everything else and then the TCI must be bad. It is possible that all of your TCIs may be just fine and that the real problem lies elsewhere. the problem being elsewhere would bring in that ugly intermittent electrical issue.

 

When I had to chase down an intermittent electrical in my ignition I made up a couple of diode boards. I used the diodes to monitor various circuits to see if I could then in real time spot the diode that blinked when it should not have. There are some circuits that should always have power so the diode would be always on. It is easy to spot when it blinks off and should not have. The other board was monitoring circuits that should always be off so that I can see a diode blink on when it should not. It is a PITA because it is impossible to find a fault in something that is working perfectly while being tested.

[mmaleney]

Did I miss your post regarding the first decision to change the TCI? Could you link it here please.

 

Steve there was no other post on this subject. I was out riding and the bike started to act up after i checked a few things I tried a spare TCI and the bike immediately ran fine. Then that TCI went bad.

 

 

Well guess I will not be out riding this fall or until I find something obvious.

[Patch]

2 TCIs in a week does raise an eyebrow and get a HUH!

 

Unfortunately there is no test for the TCI, I am sure that Yamaha once had a tester but I have never seen one or heard of one that someone had. It is a matter of eliminate everything else and then the TCI must be bad. It is possible that all of your TCIs may be just fine and that the real problem lies elsewhere. the problem being elsewhere would bring in that ugly intermittent electrical issue.

 

When I had to chase down an intermittent electrical in my ignition I made up a couple of diode boards. I used the diodes to monitor various circuits to see if I could then in real time spot the diode that blinked when it should not have. There are some circuits that should always have power so the diode would be always on. It is easy to spot when it blinks off and should not have. The other board was monitoring circuits that should always be off so that I can see a diode blink on when it should not. It is a PITA because it is impossible to find a fault in something that is working perfectly while being tested.

 

I agree with you that it is proper to test the system as a whole then, to isolate and address the malfunctioning individual parts and if none are found then assume the TCI the culprit.

 

But it's one thing to troubleshoot thru a running bike and an other to troubleshoot one that just want fire. So, if we have voltage in and switch thru TCI grounding to collapse...., then we should be able to test the TCI switching/ for troubleshooting a no spark! Its just a switch.

 

Does it apply here? This just could be an ideal situation for testing the TCI switching directly: after knowing what we all need to know first.

 

"Steve there was no other post on this subject. I was out riding and the bike started to act up after i checked a few things I tried a spare TCI and the bike immediately ran fine. Then that TCI went bad."

 

As mentioned it could be bad luck, if you believe in it.

 

Like Jefff mentioned the system needs to be tested. Personally my spidey senses say short, where that is, my first look sees would be coils then harnesses to and from the TCI. If the TCI circuitry failed twice and within a few miles then its either a bump or heat related short, so again both coils and harness need checking, especially coil 2, if the coil shorts internally or across the 2 fields then the voltage output thru and to TCI switch to ground could toast the switching circuit.

 

If not sure how to test then let us know.

[bongobobny]

Has it been rainy or excessively humid where you live? The TCI's can trap moisture inside the case which will lead to problems. You may want to take the 4 screws out and remove the cover and look for accumulated moisture inside. A common cure is to remove the cover and bake the unit in the oven at 250 - 275 degrees Fahrenheit for an hour or two, and then use vasolene or synthetic grease and put a bead around the mating surface of the cover to help waterproof the unit...

 

Relocating the TCI to the top of the airbox is also a common practice to help protect them from moisture.

[mmaleney]

I have a good harness and coils from a bike I ran for two years so I know they are good and that is easier for me to swap everything out rather than trying find bad coil's, pinched harness, corroded connectors or something that I am not sure what I would be even looking for.

 

The weather has been very wet all summer here in PA, very moist and humid. Lots of mold everywhere. So it may be that is the cause of my two a week TCI loss.

 

As always will let you know what I find.

 

Thanks to all.

[luvmy40]

This happened on my '81 SECA.

 

She just died on me. Would not start. Out of the blue.

 

I swapped the ignition module and all was good, for about two weeks. Then the exact same thing happened. Just for testing purposes, I swapped back to the original ignition module and she fired right up! That's when I did real detailed cleaning job on the connectors on the TCI and the harness, never had that problem again. I've since gone a step further with the Venture and sealed the shiny connections up with dielectric grease.

[mmaleney]

Thanks for that luvmy40, one more thing to try.