Ignition Gremlin

[gregsgt]

The EGT climb doesn't make sense to me. Dropping a mag should make the mixture more rich and EGT's climb when the mixture gets lean...

I think it sounds like a wiring problem in the ignition somewhere. Maybe a bad switch or something.

[Slyfox]

this is my thoughts. when you get your modules back, switch sides, see if it changes to the other side, if not, electrical wiring

[Dave S]

Larry,

Don't know if this would help any; but, on single ignition engines timing can drastically affect RPM. If everything else is equal (thottle the same) advanced timing will result in a higher RPM......retarded timing will result in a lower RPM...retarded timing taken to the extreme (short of killing the engine) can also result in a big RPM reduction with the charge burning partially on the way out of the engine which would possibly raise the EGT.

When you mentioned 50 and 500.....the 50 almost seems like less of a drop than a person would normally get on Rotax. If considering timing....is there any chance that the side which drops off 500 and raises the EGT is running on a severely retarded timing setting?

I don't have a clue how timing is controlled on a Rotax. Don't recall if you have the soft start (which I believe retards the timing to prevent kickback) and I don't have any idea if there is any possibility of the soft start affecting the running mode.

Again, not saying that I know anything about what the problem is; but, thought I wanted to share this possibility in case it might play into the issue.

Wish you luck in solving this.

Dave S

[Av8r3400]

These are all good ideas and I thank you for all of them!

I should be getting my modules back tomorrow and further testing will commence as time allows.

(Dam day job getting in the way of my flying fun time... )

[Av8r3400]

The ignition problem has been found.

After hours of testing and cross checking, re-testing and re-cross checking, the modules were finally found to be the culprit. Even though I had sent them both down to Lockwood for "testing" and they told me they were good. I found out later, that Lockwood can only test for function, not for "proper" function.

I believe there is a ground fault in both of the modules which cross feeds back and forth, but only when one of the two modules is shut off. I tried replacing each of the modules one at a time and the problem persisted until both were replaced. When they are both "on" they seem to function properly (but I didn't trust them).

What to do? Well, both modules need to be replaced. Yes, that hurt$. A lot. The modules on my engine are referred to as 4x1 modules, because they have a 4-pole plug and several single wires. These (of course) are the most expensive modules available because they are the oldest design (mid 90s). The latest model module is over $300 cheaper, but they come with 2 6-pole (6x2) plugs. So the guys at Lockwood were nice enough to include a parts list for all of the little "bits" to convert to the 6x2 module, which also includes the factory soft start feature. Now, even with all of the little bits, the conversion is still several hundred dollars less expensive than going with the original modules AND they are available off the shelf where the others would have to be ordered from Europe. (Where apparently there is some little guy, locked in a closet, who makes these things one at a time…)

So, today I took the (very) painful step in ordering these parts from LEAF. I will post more details when I have the parts in hand and do the conversion.

[Dick B in KY]

Larry, I feel your pain. Had to replace both modules on my 912ULS a couple years ago. Could not get them in the US, so had to get from Rotax Canada, about 1400.00. Good luck.

Dick B

[avidflyer]

Dick B. You mentioned Rotax Canada in your post, and I was wondering about prices on rotax parts from them. The Canadian dollar is now about .75 compared to the American dollar. I wouldn't think the parts in Canada all went up by 25% when The value of the US dollar went this high. The Euro is way down compared to the US dollar, close to 25% in the last 5 years (1.40 -1 then and now about 1.1-1) That alone should have caused the prices we are paying for Rotax parts to go down, being as how they come from Austria. I suppose Rotax is just gouging US customers for that much more now. Jim Chuk

[Jorket]

Is this ignition problem typical? I'm facing very similar issue...

[Av8r3400]

From what I was told by every Rotax tech and expert I spoke to, this is extremely rare. Modules are usually like light bulbs, either they work or they don't.

Describe the problem you are having. I've become a reluctant ignition expert in my own right…

[Paul Z]

Have you checked trigger coil gaps? They can make it idle poorly.
The trigger coils activate the spark plugs. I believe the spark plug gap should be .022 to .035. According to both Ronnie Smith & Eric Tucker Maintenance & Heavy Maintence Trainers it is better to set the Spark club gap at the low end, or .022. The trigger coil gaps depend on the style of trigger coil you have. If you have the "old Style" the gap should be .016 to .022, for the trigger coils with clamps the Gap should .012 to .016. According to Bryan Toepfer (CPS), Ronnie Smith & Eric Tucker, they should always be checked before putting an engine back in because they can move.