English French German Italian Portuguese Spanish Swedish

 

RPM LOST ON IGNITION CHECK

  • Navtrack
  • Navtrack's Avatar Topic Author
  • Offline
  • Fresh Boarder
  • Fresh Boarder
More
2 months 1 day ago #19183 by Navtrack
RPM LOST ON IGNITION CHECK was created by Navtrack
Hello,

While making the check of the ignition on the number 1 (A module), I have a 800 RPM lost only when the engine has been stopped after a flight or the aircraft has been parked outside in a sunny day therefore resulting within the engine cowl a hot ambient temperature. It's working well at the first flight of the day when I get out the aircraft from the hangar !

I have change the DUCATI Electronic Module with no result. I have change the ignition coils on the ignitor circuit A with no result. Does anybody has an idea what to do to solve my problem ?

Best regards,

Please Log in or Create an account to join the conversation.

More
2 months 1 day ago - 2 months 1 day ago #19185 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
"I have change the DUCATI Electronic Module"

It is not a Ducati. Did you put in a Rotax ignition module?
Since changing the module didn't help:
You most likely didn't have a real ignition module problem, but only a bad wire. Check the red wire on top of the engine to the modules, Really do a good check on the wires into the 6 pin connectors for breakage at the pin inside the plastic connector.
Did you try swapping the modules at the 6 pin connectors and see if the problem stayed the same or changed? You can ohm out some of these wires to their sources, but do these simple checks first. Most problems aren't exotic, but simple fixes. Start there first.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
Last edit: 2 months 1 day ago by Roger Lee.

Please Log in or Create an account to join the conversation.

  • Navtrack
  • Navtrack's Avatar Topic Author
  • Offline
  • Fresh Boarder
  • Fresh Boarder
More
2 months 1 day ago #19186 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Hello Roger,

Thank you for your prompt reply. The modules on my ROTAX 912ULS, mounted on my CTLS, are the original's one made by DUCATI.

At the begining, I swapped the pin connectors and had the problem on the other module. That's why I incriminated and changed it.

I will have a look on the wire and keep inform you about the result.

Please Log in or Create an account to join the conversation.

More
2 months 1 day ago #19187 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
These aren't Ducati modules.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

Please Log in or Create an account to join the conversation.

  • Navtrack
  • Navtrack's Avatar Topic Author
  • Offline
  • Fresh Boarder
  • Fresh Boarder
More
2 months 21 hours ago #19189 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Please, visit the following web site to see what is installed on my engine.

www.carmo.nl/index.php?main_page=index&c...711_4618&language=en

Please Log in or Create an account to join the conversation.

More
2 months 10 hours ago #19193 by Kevin Stewart
Replied by Kevin Stewart on topic RPM LOST ON IGNITION CHECK
My ignition modules have Ducati embossed on the outside of the cases :-) They may not be made by Ducati but they certainly have their name on them.
I've just had 2 modules fixed by Carmo, their service was excellent and quick. One had a faulty kill input, the other wouldn't fire at cranking speeds when cold. Both are known faults with these modules. You've only got to speak to the guys at Carmo to see how common it is.

Test results:
1. You have an 800rpm drop when you switch off module A when the engine is hot.
2. If you swap both of the connectors then the fault moves to the other module.
3. Replacing module A does not fix the fault.

Conclusions:
1. If switching off module A results in a large rpm drop then the module B circuit/module must be at fault.
2. If swapping the connectors moved the fault to the other circuit (ie. switching off B circuit results in 800 rpm drop) then fault is in B circuit not module.

The ignition circuit consists of:
1. Trigger coils. (cannot cause observed symptoms)
2. Charging coil.
3. Coils.
4. HT leads & resistive caps. (cannot cause observed symptoms)
5. Spark plugs. (cannot cause observed symptoms)
6. Earth connections to manifold.

Given that you have already changed the coils then I would look at the charging coil and the earth connections. You could use a voltmeter to measure the charging voltage on the red wire to each module, they should be about the same. I have some oscilloscope traces which look like they would give you about 50-100V AC at 3000rpm.

Another thought is that you could measure the resistance of the charging coils with the ignition modules disconnected and heat them up with a hair dryer to see if one changes more than the other. Good luck!

Please Log in or Create an account to join the conversation.

More
2 months 7 hours ago #19196 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
Hi Kevin,
"My ignition modules have Ducati embossed on the outside of the cases"

How old is your engine?

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

Please Log in or Create an account to join the conversation.

  • Navtrack
  • Navtrack's Avatar Topic Author
  • Offline
  • Fresh Boarder
  • Fresh Boarder
More
1 month 4 weeks ago #19201 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Roger, It's the new model, 2009.

Kevin, following is what I have done :
Ignition key on # 1 (module A) =800 RPM drop. Ignition key on # 2 (module B) = Ok
I swapped the connectors at the modules :
Ignition key on # 1 = OK, ignition key on # 2 = 800 RPM drop.

Refer to what you said, I understood that the problem is the circuit and not the module ! Would you please confirm ?

Please Log in or Create an account to join the conversation.

More
1 month 4 weeks ago #19202 by Kevin Stewart
Replied by Kevin Stewart on topic RPM LOST ON IGNITION CHECK
In answer to Roger, it is a 2003 912UL with the 4 pin plug and bullet connectors.

I don't have a key switch ignition in my aircraft, I have 2 separate switches so I cannot tell you which circuit is on in which key position. You can easily measure the kill wire connection resistance to ground whilst operating the key. The heavy maintenance manual has a wiring diagram.

From what you have just written then yes, I would agree that the fault lies in the wiring or engine side components and not the module.

Kevin

Please Log in or Create an account to join the conversation.

More
1 month 4 weeks ago #19205 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
Old ignition modules cases used to have Ducati embossed on them, but different internals were from Rotax. Now they don't have Ducati embossed on them any more.
Your problem is before the modules. Check the wires feeding into the pin connectors, ohm these wires from the back of the engine out.


Diagnostics. Heavy Maint. Manual. Section 74-00-00 page 22
3.12) Measurement values for the ignition unit
The following measurement values can be checked at the appropriate point after
detaching the plug connections.
Generator coil
(on stator) yellow - yellow 0.1 to 0.8 Ω
Generator coil yellow - ground ∞
Charging coil (on stator) red - ground 3.2 to 4.5 Ω
Trigger coil green/white - blue/yellow 115.0 to 123.0 Ω
Trigger coil new *
(with clamps) white/yellow - blue/yellow 220.0 to 250.0 Ω
Primary ignition coil connection contact - ground 0.1 to 0.4 Ω
Secondary ignition coil high voltage - High v. 6.1 to 6.7 kΩ
Spark plug connector 4.4 to 6.0 kΩ

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell
The following user(s) said Thank You: admin

Please Log in or Create an account to join the conversation.

  • Navtrack
  • Navtrack's Avatar Topic Author
  • Offline
  • Fresh Boarder
  • Fresh Boarder
More
1 month 4 weeks ago #19208 by Navtrack
Replied by Navtrack on topic RPM LOST ON IGNITION CHECK
Thank you Roger, I keep you inform with the result.

Please Log in or Create an account to join the conversation.

More
1 month 3 weeks ago #19269 by Flyingforx
Replied by Flyingforx on topic RPM LOST ON IGNITION CHECK
I seem to be having similar issues with my 2016 912 uls. Less than 100 hrs. Starts right up, but 1400 + drop on module B at 3800 rpm and it is missing and popping. Still on original plugs. Testing at idle only yields 400 rpm drop and engine runs smoothly on both modules. Synced and checked the carb bowls, swapped plugs, swapped modules, swapped red stator wires, gapped trigger coils, checked their resistance all in the 248 ohm range. All with no noticable change, swapped input coil harnesses and p leads which did lead to opposite switch making the larger drop... Have I overlooked something?

Please Log in or Create an account to join the conversation.

More
1 month 3 weeks ago #19272 by Flyingforx
Replied by Flyingforx on topic RPM LOST ON IGNITION CHECK
Could a ignition module be stuck in soft start mode? The issue I'm having seems like a timing issue. Smooth low idle up to 2400 on module B. Then coughs and backfires above 2700. Engine runs great on both.

Please Log in or Create an account to join the conversation.

More
1 month 2 weeks ago #19274 by Roger Lee
Replied by Roger Lee on topic RPM LOST ON IGNITION CHECK
Are you sure it's electrical? Have you put a set of carb sync gauges on yet to rule this out. That's cheap and easy to check. Then move on to a more complicated electrical issue. Do you have someone you can swap ignition modules with for at least one start? Do you have separate ignition switches or a rotary switch?ignition

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-574-1080 Home (TRY HOME FIRST)
520-349-7056 Cell

Please Log in or Create an account to join the conversation.

More
1 month 2 weeks ago #19277 by Flyingforx
Replied by Flyingforx on topic RPM LOST ON IGNITION CHECK
I have synced the carbs three times using two vacuum gauges and have it down to two needle widths apart at 3800 (where I do my checks). I have separate switches. Question is when I swap the pickup connections (the six pin plugs to the triggers) the switches flip, when I change the output connections, nothing changes. Would a module off an older (1994) rotax work for testing purposes?

Please Log in or Create an account to join the conversation.

More
1 month 2 weeks ago #19278 by Flyingforx
Replied by Flyingforx on topic RPM LOST ON IGNITION CHECK
Or should I be looking at pickup coils?

Please Log in or Create an account to join the conversation.

More
1 month 2 weeks ago #19280 by garrett
Replied by garrett on topic RPM LOST ON IGNITION CHECK
Make sure the carburetor piston slides up and down easily. Sometimes they get gummed up and cause similar issues. they have to move freely.

Please Log in or Create an account to join the conversation.

More
1 month 2 weeks ago #19281 by Kevin Stewart
Replied by Kevin Stewart on topic RPM LOST ON IGNITION CHECK
"swapped input coil harnesses and p leads which did lead to opposite switch making the larger drop..."

If swapping the input connector over causes the fault to transfer to the opposite ignition then the fault must be ignition and not carburation. The input connector comprises of the following:
1. two inductive trigger coils
2. the ignition charging coil
3. the kill switch connection

You can measure the resistance on the two charging coils and they should be similar and be within the published limits. I cannot imagine that the kill switch input would give your symptoms unless you had some very odd modulation on that pin. A problem with the trigger coils could give you a timing problem. The ignition module only knows which timing signal to use based on their amplitude. If you have a low output from one of the coils then it is quite possible that the module will think that it is in the cranking phase of engine start and will apply the appropriate ignition timing.

If you have access to an ignition strobe light then you can turn the engine to TDC and paint a white mark on the flywheel and on the crankcase housing. If you observe the timing marks when the engine is running they should appear fixed at all RPM on both ignitions. If they are not then you know that you have a timing issue. The fact that swapping the trigger coils over moves the fault to the opposite circuit says that you probably have low output from one of the coils. You could measure the voltage from each coil with a multimeter set to AC volts. The would identify the problem coil. Alternatively resistance measurements might shed some light on the fault. I would wiggle the wires whilst making the measurement in case there is a wire break.

Please Log in or Create an account to join the conversation.

More
1 week 4 hours ago #19691 by Flyingforx
Replied by Flyingforx on topic RPM LOST ON IGNITION CHECK
Delayed reply here, apparently I had a bad ignition module that resulted in the larger drop in one side. After troubleshooting everything else, I borrowed a friend's module and the problem was solved...
The following user(s) said Thank You: admin

Please Log in or Create an account to join the conversation.