TCI (DCI?) going bad?

[fintip]

A little research brought up a looot of different conflicting information, so one more thing that should be added to the wiki and now I need for myself:

What's up with the brains of our bikes? Can I swap out an '87 TCI for the TCI (or is it a DCI? Is that the same as a CDI? What the hell is up with all these acronyms for something that does the same thing anyways?) on the '90?

I'm having running problems. I think it's tight exhaust valves, mechanic friend (who got a symptom list secondhand, hasn't seen it running or talked to me about it yet) supposedly suspects that the TCI is going out, which was actually my first thought. My symptom list:

I think it's tight exhaust valves from the symptoms. Seemingly overheating, started to accel inconsistently with a fixed throttle position, hot start issues, power robbed, backfiring on decel; forgot that since rebuilt and has racing valve springs, probably needs adjustment sooner than expected. A long trip on a hot day showed the symptoms more clearly than daily short commuting, where it never hit full temps.

One symptom not explained: tachometer started going haywire at the same time. Really threw me for a loop. Thought at first it might be my TCI going bad, but the temp-dependent symptoms (it runs better, but still somewhat awkwardly, when truly cooled down) made me think otherwise.

I've got a spare '87 TCI off my project FJ; will it work to test that theory, or is it not compatible?

[Fj.itis]

I always thought the tci either worked or it didnt. Have you checked all your grounds for a possible loose earth?

Tci is transistor controlled ignition and dci is digital controlled ignition. They are different, not sure on fitment.

Another thing since you mentioned tacho, check the wire going to the tacho as if it grounds to engine or frame then it runs like crap.

[JPaganel]

TCI is Transistor Controlled Ignition. It's what FJs have. The electronics control the coils by grounding via output transistors.

CDI is Capacitive Discharge Ignition. It's an earlier electronic ignition design. For all intents and purposes it's still a black box, but the coils are controlled via sending a high-voltage pulse to them.

TCI and CDI are not at all interchangeable. Using a CDI in place of TCI can fry the coils.

DCI can stand for Direct Coil Ignition, Dual Coil Ignition, Digitally Controlled Ignition, but I am pretty sure those are essentially brand-specific marketing terms.

[fintip]

it's what FJ's have

My interest in the acronyms was merely passing. I understand the difference in theory, I was just expressing annoyance at something silly. I also know they aren't interchangeable.

The only real question I have, is: is the same TCI used on all models of FJ/if they're different, are they interchangeable?

[aviationfred]

From the part number interchangeability on Partzilla, The answer would be no. The Igniter unit for your 90' will work on 89'-96'.

84'-85' interchange

86'-87' interchange


http://www.partzilla.com/parts/detail/yamaha/YP-3SK-82305-01-00.html

Fred