EI EGT Readings

[AZOutlaw]

I've got the Electronics International EC-1.  A real simply toggle readout to a single CHT and EGT.  Recently the EGT started jumping all around.  The CHT reads good all the time and the EGT reads air temp when in the hangar but start it up, and it loses its mind.  This tells me the gauge, or readout, is fine.  My probe seems to "ohm" out fine based on what they say it should on the EI website.  I think it may be the connectors.  They are the cheap push in type which seem more suited for a toaster than an airplane.  Anyone have experience with this?  Should I dump the connectors and solder the wires together? 

[N601RX]

It's likely that the egt probe going bad. These take a lot of abuse in the exhaust stream. It's probably intermittent when the hot gas is applied to it.

[HRM]

I've got the Electronics International EC-1.  A real simply toggle readout to a single CHT and EGT.  Recently the EGT started jumping all around.  The CHT reads good all the time and the EGT reads air temp when in the hangar but start it up, and it loses its mind.  This tells me the gauge, or readout, is fine.  My probe seems to "ohm" out fine based on what they say it should on the EI website.  I think it may be the connectors.  They are the cheap push in type which seem more suited for a toaster than an airplane.  Anyone have experience with this?  Should I dump the connectors and solder the wires together? 

 

They actually are not "cheap" and are the best way to install the EI system. I have an MVP-50 which is a bit more sophisticated than an EC-1 and it has a significant number of those connectors. I will tell you that if they are not installed correctly they will give you problems. If they are installed correctly they are a godsend in terms of maintenance and replacement.

 

If you want headaches, go ahead and solder everything up. Who installed the unit?

[takair]

As Mike, 601RX, suggested, check the EGT probe. You will likely find the outer metal housing is breached. I think you will find that the connections are not easy to solder and may set up another cold junction that may just skew readings. I have had good luck with the stock connectors, I think I have 16 on my engine.

[AZOutlaw]

Thanks for the input and HRM, I do not know who installed it. As I mentioned, I checked the probe with my voltmeter and seem to get the ohm numbers they called for. The EI website says to make sure the wire is bent in half before crimping into the connector. I pulled hard on all 4 and one came off, and had a short piece of straight wire. Hope this is it. I'll let you know.

[Lood]

I once had a similar problem with one of the CHT's on my EDM700. Upon checking, I found one of the terminals not being crimped properly, so with engine vibration, it didn't make good, continious contact. I crimped it properly and made sure that the terminals fitted tight - problem solved. Could aslo be the probe as mentioned above.

[AZOutlaw]

I re-crimped the terminals with no better luck so I went ahead and ordered a new probe.  Does anyone know the correct immersion depth of a Electronics International P-110 EGT probe.  There's a real nice instruction sheet with great information, it just doesn't mention how far to put it into the side of the exhaust pipe.  By the way....the new probe comes with a much improved mechanical connector.  They don't like the crimp-ons either. (I will not call them "cheap" again)

[Vance Harral]

Does anyone know the correct immersion depth of a Electronics International P-110 EGT probe.

 

The installation instructions for the "fast response" flavor of P-110 specify 3/8" from the shoulder to the ferrule, which results in about an inch of the probe being inside the exhaust pipe.  I'd guess this is sufficient for the "massive" flavor of P-110 as well, but I actually don't think it's a critical measurement.  The round end of the probe that goes inside the pipe is just a housing.  The thermocouple junction is inside that housing, and as long as it's inside the pipe, it should be fine.  Sliding the probe further in/out of the pipe may vary the measured temperature a few degrees, but EGTs should be interpreted as relative rather than absolute numbers anyway.  If it makes you feel any better, our probes are installed 4" down from the exhaust ports rather than the recommended 1.5", and that's not an operational issue for us.

 

I hear you about the old style connectors.  We had all kinds of trouble with them on one cylinder, and needlessly replaced at least one good EGT probe before figuring out the issue was wire breaks at the connector crimp joint, rather than the probe itself.  EI sent us a bag of the new style connectors, which we installed on the EGT probe for the troublesome cylinder, and haven't had a problem since.  I keep wondering if I should replace all the other old style connectors as well, but those have held up OK for whatever reason.  My guess is the EGT installation on the troublesome cylinder experiences more vibration than the other locations.

[AZOutlaw]

Thank You Vance.  I saw that note but since I didn't have the "fast response" version I had no ferrule to measure off of.  I had I call into Electronics Int. and they did call back late yesterday.  They told me the end of the probe should be as close as possible to the center of the exhaust pipe. 

The reason I was asking this is I was still having jumpy readings with the brand new probe.  I did some digging under the dash this morning and found more of the fabulous crimp connectors that were loose.  I would sure suspect that all will be good when I fire it up this time.