Elec.issue

Recently my Cht shows that when I turn on nav lts. Strobes my get and Cht start jumping up in big increments turn them off and goes back down what can be the issue here rky.mt. Inst monitor never had issue before 200 hrs. Help!

Huh?

Please check your post - I don't understand the problem.

Check your grounds.

Vic

Elect.issue

Ok I'll check wow where to start right!!

Primary suspect would be grounding between the engine block and the airframe, it needs to be grounded well or you'll see problems on the thermocouples for CHT and EGT just like you describe.

Elect.issue

Ok down to airport today all grounds check out, the interesting thing I did find out was with the engine running no nav lights on or strobes or taxi/landing lights on Cht reads normal steady to rise, but turn any light on up shoots egt very rapidly turn off back down, then switch off main buss and turn lights on all is normal. So does this tell me alternator is the issue perhaps?

Any feed back would be appreciated thanks.

Still sounds like a grounding issue, but...

Your voltmeter tells you whether the alternator is doing its job. If it's charging, you should be seeing ~14 volts on the bus. Anything under ~13.5V is a strong indicator that the alternator isn't working. Having said that, it's unlikely that loss of alternator would cause your symptoms, unless your battery voltage is so low that it's causing abnormal functioning of your engine monitor (possibly <10.5V, depending on the instrument).

almarsh said:

Recently my Cht shows that when I turn on nav lts. Strobes my get and Cht start jumping up in big increments turn them off and goes back down what can be the issue here rky.mt. Inst monitor never had issue before 200 hrs. Help!

Click to expand...

Does the behavior happen with just Nav, Just Strobe or only with both? You should individually turn on every high draw device and see which cause the reading problem to appear. This will help to isolate whether the Eng monitor is overly sensitive (not likely given the symptoms) or if the problem is being caused by one device/circuit. As you experienced in the first 200 hours, your strobes should not be affecting the instrument. Something has happened and you'll need to do some troubleshooting / isolation to know where to look.

It is not likely your alternator. Your CHT monitor shouldn't start behaving oddly before other devices also do, if caused by low voltage. Further, if you had enough battery capacity to start the plane, low voltage wouldn't magically appear as you switch on the strobes and disappear when you turn them off.

Larry

Larry

almarsh said:

Ok down to airport today all grounds check out, the interesting thing I did find out was with the engine running no nav lights on or strobes or taxi/landing lights on Cht reads normal steady to rise, but turn any light on up shoots egt very rapidly turn off back down, then switch off main buss and turn lights on all is normal. So does this tell me alternator is the issue perhaps?

Any feed back would be appreciated thanks.

Click to expand...

Try this - with engine running, shut off the alternator so you are operating on battery power only - now repeat the lights on/off like you did earlier - what happens with the CHT/EGT?

almarsh said:

Ok down to airport today all grounds check out, the interesting thing I did find out was with the engine running no nav lights on or strobes or taxi/landing lights on Cht reads normal steady to rise, but turn any light on up shoots egt very rapidly turn off back down, then switch off main buss and turn lights on all is normal. So does this tell me alternator is the issue perhaps?

Any feed back would be appreciated thanks.

Click to expand...

How exactly do you turn your lights on with the "main buss" off? You need a bit more detail here for us to help.

Larry

Elect.issue

Thanks to all I found the problem to master switch wasn't grounded at toggle tightend up my nut that holds toggle to panel issue solved.

If your master is getting its ground through the mounting nut, it would be worthwhile to take another look at your wiring architecture. The master should have a ground wire back to the primary ground location (forest of tabs, battery negative, etc). As you discovered, it was finding its ground through whatever other devices it could. That could have bi$$er ramifications than errors in CHT readings.

Charlie

Elect.

Yes you are right I'm ivestigating that tomorrow thanks for pointing that out nothing like feeling stupid, but better to feel like that than more serious issue later.