LSE ignition advice

kaweeka · #1 03-09-2019, 10:16 AM

I have dual Lightspeed Plasma III on my IO 320 B1A with Airflow Performance FM-100 injection. I run the Denso IK27 as suggested by Klaus and replaced my plug leads last year , again, as suggested in the maintenance manual. My Fuel injection was inspected and serviced by AFP this year as suggested in their manual as well. Recently, I've noticed a roughness or a missing at idle. My EGTs and CHTs are grouped nicely in cruise running LOP with the only outlier being cylinder #1 which runs about 30 degreed cooler than the rest. I get the sense there is something not right in my ignition but can't put my finger on it. I asked Klaus how to tell if individual components in the ignition system are functioning properly but don't get an answer. Could there be a problem in one of the coils? Modules? are the new leads the problem. The troubleshooting flowchart notwithstanding,I'm reaching beyond my knowledge base and experience. It used to fire right up and run as smooth as can be but now it takes a little more effort to start and round a little rougher at idle. Any guidance would be appreciated.
Cheers,
David

Toobuilder · #2 03-09-2019, 01:33 PM

Two things to check right away:

Induction leaks

Plugged injectors

lr172 · #3 03-09-2019, 02:43 PM

Quote:

Originally Posted by kaweeka

I have dual Lightspeed Plasma III on my IO 320 B1A with Airflow Performance FM-100 injection. I run the Denso IK27 as suggested by Klaus and replaced my plug leads last year , again, as suggested in the maintenance manual. My Fuel injection was inspected and serviced by AFP this year as suggested in their manual as well. Recently, I've noticed a roughness or a missing at idle. My EGTs and CHTs are grouped nicely in cruise running LOP with the only outlier being cylinder #1 which runs about 30 degreed cooler than the rest. I get the sense there is something not right in my ignition but can't put my finger on it. I asked Klaus how to tell if individual components in the ignition system are functioning properly but don't get an answer. Could there be a problem in one of the coils? Modules? are the new leads the problem. The troubleshooting flowchart notwithstanding,I'm reaching beyond my knowledge base and experience. It used to fire right up and run as smooth as can be but now it takes a little more effort to start and round a little rougher at idle. Any guidance would be appreciated.
Cheers,
David

Can you pinpoint when it started running rough? Possibly associated with one of the tasks mentioned or possibly something else. If you can associate the trouble with some work that you did, that should point you in the right direction for troubleshooting.

Larry

pitts flyer · #4 03-09-2019, 02:56 PM

I run dual lightspeed also on my Pitts. A couple of years ago now I had a rough running problem but seemed to show up only an occasional miss at higher RPMs. I checked everything (I thought), including replacing the spark plug wires which were then about 5 years old. To make a long story short, it was an intermittent bad spark plug causing the problem.

To add to the story, I had rotated some new spark plugs in and then rotated them again, when the problem persisted. But I had managed to get the one bad plug in both times as luck would have it--I got them mixed and goofed. Only when I replaced all with new was I able to solve the problem and identify the bad plug.

Anyway, worth checking if you have not done so already.
PS: Klaus was of no help in identifying this problem.

Kent Ashton · #5 03-10-2019, 03:52 PM

I had miss caused by a bad coil. It was corrosion from water getting into the coil tower. Separately, I also had a miss in a Plasma III. Turns out Klaus had a chip or chips that were not well supported and broke connections. He fixed it but it was rather expensive and he doesn't publicize the problem on his website. Otherwise they've been trouble-free.

rvdave · #6 03-10-2019, 04:04 PM

I have dual light speed plasma iii and had rough running at idle and had problems leaning to below 12gph. I started with suggested ik01-24 iridium plugs. Tried many other plugs to no avail. Had my airflow performance fuel system injectors adjusted. Checked and replaced some plug wires. Tried isolating plug wires and insulating from input wires. All to no avail. Problem went away after gapping iridium plugs to .027 gap. Although they don?t recommend regapping the iridiums that solved my problem, now I can lean to whatever I want to within reason. Other thing I did after the fact to smooth out idle more was to richen the idle mixture.

Lars · #7 03-10-2019, 09:57 PM

Each coil fires two plugs. If the processor or primary wire is failing and affecting a coil, then two cylinders will have issues. OTOH a failing coil could affect one cylinder. I removed a Plasma II system from an RV-8 last year where the posts on one coil had rotted off the coil, presumably from corrosion although the source wasn't obvious. It apparently was running fine in spite of that, though I didn't fly it so I can't confirm.

And as others have pointed out, defective (despite new) plug, bad (despite new) plug wire.

Last but not least, as Michael pointed out, check for induction leaks and a plugged injector.

kaweeka · #8 03-11-2019, 05:22 AM

I appreciate all the replies. I have Thursday off and plan on spending the day looking carefully and following the troubleshooting table carefully as well as checking the ring/sensor gap and alignment. Report to follow.
David

dougweil · #9 03-11-2019, 02:49 PM

Check to be sure that you do not have a missing insert in a fuel injection nozzle. Will make one cylinder run excessively rich. Ask me how I know!!!!

kaweeka · #10 03-14-2019, 03:29 PM

After systematically making my way through the Lightspeed troubleshooting algorithm and finding everything in working order, I then turned to check for any induction leaks of which there were none. The last step was something that Don Rivera pointed out. When I received my Airflow back from inspection and maintenance, I put it back on the aircraft but did not recalibrate the idle mixture after installation. Upon reflection, that was about the time when I noticed the difference. Today, I set the mixture. The plane ran smoother at idle, started much better. It appears the simple solution was the correct one.
Off to San Diego this weekend and Cabo in April....

David