New EGT probe different

[jc2da]

I am having difficulties with new EGT probes bought just a few weeks ago. At first i thought it was a cylinder problem - ruled that out. I bought 2 new probes and the 2nd behaves exactly the same as the first.

My original EGT probes were bought about 2 years ago. They have the red plastic quick connectors on them. One of them started to flake out on me, so i ordered 2 new EGT probes a few weeks ago.

Below is a photo of the slip with the new ones. They also have a more clear plastic connector on them, as opposed to red.

I have noticed some peculiarities with the new probe. At low EGT temps, it seems to be inline. However, at higher temps starting around 1400, the new one seems to read at least 50F to 100F and even higher than the older probe. I have even seen the probe increase and increase until it hits my max value of 1600F.

I swapped the probe with a different cylinder, and sure enough it is not a lean cylinder problem. The problem stays with the new probe even on a different cylinder.

Has anyone else gotten a new EGT probe and seen anything like this? I've already called support and apparently, this is the first report of this type of issue.

Thanks!
Jae

 

[rogersmart]

I have the same problem, I replaced 2 EGT sensors in January 2013. The 2 new ones show readings similar to the old ones at low temperatures. When cold they display the same ambient temperature within 1 degree. Both new ones show higher temps as the temps rise reaching as much as 75 degrees higher. I also swapped cylinders and the higher readings followed the new sensor. I made the assumption that Dynon had a different supplier but also felt the sensors might read higher when new. Neither is an acceptable situation as the sensors should read accurate or their value for information is diminished. I have not had the time to pursue it but since you have brought this up I would love to hear what Dynon says about it. My original sensors are about 4 years old.

 

[jc2da]

ok, thanks for the report. that makes at least 2 of us with similar issues. if people are starting off with these defective new probes, they are in for a world of hurt.

also, in my case, it is not just an absolute value issue. the new probe behaves differently at the higher temps where i cannot find peak EGT like i used to. according to the new probe, the peak EGT is now 2GPH higher than with the old probe. there is just something wrong with the new probes.

i have done several tests to isolate that the issue is with the new probe, and not a lean cylinder or cylinder specific.

 

[tommyturner]

I also installed a new EGT probe 3 weeks ago and the temp readings are 50 to 100 degrees higher than the old probe when running lean of peak at cruse.

 

[mmarien]

I always wondered if EGT probes were calibrated. and did they deteriorate with age. Turns out that they are a consumable as they don't last forever.

According to Mike Busch the absolute EGT doesn't mean a lot. His method of leaning doesn't use EGT's and his twin TIO550s have been running for over 4000 hours.

When I upgraded to electronic fuel injection the EGT ran so hot they eventually fried my EGT probes. When I did the research it turns out that there was not a lot to worry about. I replaced the EGT probes with a better quality probe (good to 2000F). Not that I use them for anything anymore, but they didn't look good on the screen when they didn't work.

When it comes down to it there are two things I care about in engine performance. That is maximum power (for climb) and best economy (for cruise). Peak EGT is an indication of stoichiometric or ideal fuel mixture but you can't use EGT to determine maximum power or best economy. You need an oxygen sensor to measure the air fuel ratio (AFR) to determine power and economy mixture settings.

EGT does have an application in engine analysis. If you want to find out what the EGT is telling you download the Skyview user log and use Mike's web site to do some free analysis.

 

[jc2da]

Here is a quick update on my experience thus far.

The EGT probe is still reads high but maybe slightly less high. I adjusted all of my EGT warning and alert levels about 50F or 100F higher or so to account for the higher readings.

I think the new EGT probe gets better over time - ie less peaky highs and less absolute highs than before. That is just my experience over the past 20 hours or so.

https://www.savvyanalysis.com/flight/357500/537b3a2c-6754-4fb6-935e-2ba7056f1067

E.g. this is my very first flight with the new EGT probe on #4. You can see there is little correlation between the #4 and other cylinders. It was so bad, i thought it had to be a fuel issue.

https://www.savvyanalysis.com/flight/374556/cd2d98cf-9fe5-405a-8261-57fb690b5118

This was on a recent flight. EGT4 is still high but less so. It also rises and falls the same as the others now.

Hope this helps someone.

jae