Could it be the coil?

Got my 650 max running. It was going strong, for about a week.

Now its starting on 2 cylinders again, checked sparks. 2 & 3 have no spark. OK, they're controlled by the same coil right?

Did the primary coil test last night and was getting 3.1 ohms.

Secondary just read 1

Before I assume bad coil, could there be another issue mimicking this?

New spark plugs last week

 

Swap the coils and wires, see if the problem follows.

 

Like hook up the 1/4 coil to the 2/3 leads and vice versa?

 

Spoken like a true aircraft mechanic.

If you just swap the spark plug wires, it won't fire cuz they are firing on the wrong sequence. Swap the 1/4 and 2/3 wires, and the input wires from the TCI, right

 

swap the wires, all the wires. The big wires and the little ones.
you want to make the 2/3 coil run the 1/4 plugs and visa versa. then you know if it's the coil or the pick-ups

 

I think its my spark cables. Chopped a cm off of the end of each and now my cylinder 3 is firing strong.

How do I remove the cables from the coil so I can try switching them? I pulled a little on them and they didn't budge, generally the "let's just pull on it until it comes out" mentality usually doesn't work out for me.

If they aren't too expensive I might just replace all my cables and caps

 

If they are the original coils, removing the cables is very difficult and requires a little surgery. Easier to trim the cable as you have and install new caps, splice new cables and caps onto a short piece of existing wire, or to replace the cables, caps, and coils wholesale.

 

I see there's some NGK cable splice units, anyone ever used one?

http://www.amazon.ca/NGK-J-1-Racing-Cable-Splicer/dp/B0018JXIXI

 

I have used them, and like them very much. You'll want to leave a few inches of the old plug wires so there is enough room for the splices to rest between the tank and engine. The remaining old plug wires can be insulated with self-amalgamating tape.

 

Sighhhh

Its the coil

Or my TCI which I can't test because there's no test values in the manual

Or my ignition timing

 

Ignition timing is non-adjustable (advance is controled by the TCI), so you can rule that out.
One of the ignition pickups could be bad (there are test values for them).
There are test values for the coils.
There is a way to test the TCI, but you either have to swap it with a good TCI, or have a compitent repairman open it up and test the components.

Did you ever swap the wires around to see if the problem followed the position of the swap?
DOnt' forget that you may have more than one problem in the system, so don't think of your work as having been worthless.

 

Ignition coils are reading out of spec, 3.1 ohm on primary coil, 18500 ohm on secondary (now that i replaced the corroded spark plug wires I can get a reading)
Pickup Coils are reading in spec 690 ohm, spec is 700 +- %20

Here's how I tested manually
- switched caps from cylinder 2 to cylinder 3, still no spark on 2 (caps both read in spec)
- switched wires from cyl. 2 - 3 still no firing on #2
- switched inputs to coil from 1/4 to 2/3, and ran 1/4 leads to cylinders 2/3 and ran 2/3 leads to cyl 1/4, problem followed to cylinder 1

 

Good work. If you have it in your budget you should get new coils. Used will be fine, but why waste an oppertunity.

 

Got OEM coils tested in spec, bang on in spec actually. Literally had it running on 4 cylinders for like a day, then I busted my idle mix screw.
I fixed that problem, now I'm back to no spark at 2/3 again . I have newish resistor plugs, HT leads from coils test 11 100 ohms, now my caps won't ohm out and I get an open circuit when I try test across them.

I should be getting the same base reading as when I touch the multimeter electrodes together, through the cap right? I got a flash reading of 599 for about 2 seconds across one of them, can't get a reading from the other. What really bums me is that these things just keep breaking in sequence, it seems like whenever I add a new element to my ignition system, something else goes


*slamming face into wall

 

I don't think my plugs are fouled, when i put the 2/3 plugs into 1/4 and vice versa, same issue on 2/3

 

Uh ohhhhh, just did some digging.....Could this cause lack of spark? I think its the point for 2/3 no?, it has the grey lead

 

Is your pickup "chipped" in the pic? If so, then yes, that could definitely cause an issue with cyls 2 & 3 'missing', or going dead all-together. New pickup lead would be an order.

 

Yupp its chipped, dont know how it happened. I always make sure not to ram into it if im turning the engine by hand, guess i need to be more careful