EGT CHT readings false on #1 cylinder

[Remy]

Hello All,
Before starting, all EGT are reading OAT, but after starting, #1 cylinder shows red cross on CHT and a false reading on EGT, very lower than the others
Checked connections, ane discrepancy is still here
Any idea?

 

[SkippyDiesel]

Check that the thermocouple/sensor is working correctly - swap EGT and see of the problem moves or stays

 

[RVDan]

the EGT thermocouples can fail like this. I would swap thermocouples and see if the problem follows.

 

[prepperpilot]

I am having same problems on one CHT probe. Temps All over the place. CHT is consistent. Gunna switch out sensor probe soon. I know it's annoying! Don't freak out

 

[WenEng]

Mine was a poor electrical connection where the thermocouple wire connects to EMS wire.

 

[SkippyDiesel]

I have two EGT probes. Since installation they have never been balanced (the same). Checked everything, decided is just the probe. Reading is consistent on every engine run. Disconcerting at the beginning, now just annoying. living with it

 

[swatson999]

I have two EGT probes. Since installation they have never been balanced (the same). Checked everything, decided is just the probe. Reading is consistent on every engine run. Disconcerting at the beginning, now just annoying. living with it

EGT as an absolute value means nothing. Each probe is going to end up in a slightly different position, different distance from the exhaust valve, slightly different angle in the pipe, any one of a dozen things.

What matters is the *behavior* of the EGT values...do they all rise and fall together when leaning? Do they all rise when you do a mag check, etc.

The actual numbers are kinda meaningless.

 

[Remy]

Be aware that sometimes Dynon inverts EGT and CHT probe labels...check wires colors instead
That was the issue....

 

[swatson999]

Be aware that sometimes Dynon inverts EGT and CHT probe labels...check wires colors instead
That was the issue....

What labels? As I recall, there are no labels on the wires themselves.

Or do you mean you hooked up an EGT probe to a CHT extension lead from the EMS, or vice-versa?

 

[Remy]

That is right
EGT and CHT EMS harnesses are labelled

 

[swatson999]

That is right
EGT and CHT EMS harnesses are labelled

I know. So what do you mean "sometimes Dynon EGT and CHT probe labels"?

Are you saying you got a harness with EGT wires labelled as CHT, and/or vice-versa?

 

[Remy]

CHT and EGT Probes labels of Cylinder 1 were inverted

 

[swatson999]

I'm having a tough time believing that Dynon mislabelled a stock EMS EGT/CHT harness...

 

[Cliffy]

I was told by a very knowledgeable source to get the little hook up tubes with set screws that EI uses for their EMS and remove the spade connectors the Dynon uses out at the wire splices.

 

[SkippyDiesel]

I was told by a very knowledgeable source to get the little hook up tubes with set screws that EI uses for their EMS and remove the spade connectors the Dynon uses out at the wire splices.

Spade connectors have been "bagged" as unreliable, pretty much since they became commonplace electrical system connectors and yet they continue to be used in domestic, automotive ,agricultural, marine, small aircraft, etc applications.

They;

• Work well when tight, not subject to vibration and corrosive environments.
• Are relativly cheap, quick & easy to install/connect

The key to their function is correct installation - use a proper crimping tool, use the correct connector for wire size, purchase quality connectors that are tight/secure when male/female inserted, support the cable/connections to reduce effect of vibration, protect connections that may be exposed to weather/salt atmosphere (a smear of dielectric grease may help).

All the electrical connection systems work. It's up to you to decide which one will best suit your application. I would caution against complex multi part systems.

 

[GKC Aviation]

I was told by a very knowledgeable source to get the little hook up tubes with set screws that EI uses for their EMS and remove the spade connectors the Dynon uses out at the wire splices.

Do not use these, they are the worst.
They are called an OLC-2 connector, and EI have been supplying them for years.
I can't tell you how many I have removed due to causing all kinds of problems.
They are first thing to go in the bin when I install anything from Electronics International.
Mind you, the first thing to go in the bin when I install Dynon systems are their spade connectors supplied with the EMS.
AMP spade connectors installed correctly with the proper crimp tool, and heat shrink over the top have never let me down.
You will find this issue commented on many times throughout this forum.

 

[jakej]

As GKC said & I've posted several times on this forum about the reasons why some are having issues - IMO, the only simple cost effective connectors (female side is already on the probe) are the AMP brand however you should use a double jawed crimper & nowadays I also spray the connectors with contact cleaner before and after crimping - these are lessons learned during more than 800 (not kidding) thermocouple connections. I do installs all over Oz & the last thing I want is a callback due an issue that could have been prevented. YMMV
Ps - the original early probes & wire were a single conductor that needed a simple solution to rectify 'issues'.

 

[Cliffy]

I do have the proper crimpers but the problems I have seen (just a few) is with the sliding connection and not the crimp portion.
I can unhook and reslide the connection and the issue goes away for a while- sometimes to return.

 

[jakej]

I hear you but are you using the AMP (TE) brand ?

 

[Cliffy]

In looking at the AMP TE connectors on line I'm certainly not currently using "them".
I have only used single connection spade connectors as those kind supplied by Dynon.
In a quick look on the AMP website my first concern is Mil Spec compatibility.
I haven't seen that reference yet for use on certified aircraft
If I was working on Experimental aircraft my first impression of TE is that they are a superior
connection than what I have used for years. Using single spade connectors has been a bane
of mine for a long time as I have always felt there had to be a better way.