EGT and TIT

JPI now has a screw-in type TIT probe – P/n 1020062 – Size: 7/16″.

If you need a different size, please go to Alcor’s web site at:

http://www.alcorinc.com/sensors/category-02.php

2 to 4 inches are recommended. Closer will shorten the life of the probes. Farther from cylinder head – up to 53/4″ – from exhaust stack flange is okay. Uniform spacing is important. Temperature differences of 100 degrees per inch can be expected.

We have larger clamps available. Call JPI 800-345-4574

Remove and squeeze the thimble and reassemble.

EDM-700/800 Pin assignments on the P1 connector:
yel 1, red 2, OIL
yel 3, red 4, IND
yel 5, red 6, CARB (or CDT)
yel 14, red 15, OAT
yel 16, red 17, TIT
yel 18, red 19, TIT-2 (2nd TIT)
gry 12, Remote alarm (Sinks to ground)
red 13, + Power
wht 24 , RS-232 data port
blk 25, Engine ground.   ** ( Pin # 11 not used.)

This is normal. Due to unburned fuel air continuing combustion in exhaust manifold

Yes, IF the aircrafts TIT probe is the same type thermocouple. ( Type K red and yellow wire.) Just parallel the conection. Connect red to red and yellow to yellow. See the EDM-700/800 Installation manual Report #103 under “Turbine Inlet Temperature Probe (TIT)”, or Installation Manual Report # 760 under “Turbine Inlet Temperature Probe (TIT)” for the EDM-760.

Calibration procedure:

1. Go to pilot program mode (Hold both buttons to see PROGRAM).
2.Tap STEP until you see RATE.
3. Hold both buttons until you see ORIGT-N.  ( ‘ORIG TIT?N’ for the 760)
4. Tap LF to change to ORIGT-Y. Now tap ‘Step’.
5. See CAL TIT then ‘TIT+0’.     ( ‘TIT ADJ + 0’ for the 760 )
6. Tap or hold LF to change the correction factor (Ex: if the EDM reads 100 less than the aircraft’s TIT, set the display to read TIT+100)
7. Tap STEP to exit.

  • The EDM might be in the Normalize view. Switch to Percentage view: hold LF button for three seconds.
  • Might be in Celsius units but the alarm limits are still set for Fahrenheit.
  • Check that if a bayonet or threaded adapter probe is installed, that it is screwed in tightly and the threads are clean in order to ground the factory probe. If adapter is not grounded well to engine, voltage will be applied to the adapter thermocouple junction and disrupt the EDM instrument.

May be an ungrounded probe, only replace with an ungrounded probe

2 to 4 inches are recommended. Closer will shorten the life of the probes – flame-front is at 1.5″. Farther cylinder head? (Up to 6 inches) is okay. Uniform spacing is important. Temperature differences of 100 degrees per inch can be expected.

Up to 150 degrees DIF is okay.

  • Unit starts reading at 825F.
  • Or the unit may be set to Celsius without changing the red line limits (set TIT for EGT limits). Set TIT limit to about 900 degrees C. When changing to Celsius all alarm must be reset to Celsius limits.

Check EGT digital reading on that particular cylinder. If lower than 825 degrees bar graph will not show. If 800 or lower, check probe and connections.

Check at ambient. Check as temperature rises to see where probe fails. Three causes for removal from scan are:

  • Open probe – shows error
  • Low probe reading when EGTs>1000 degrees – digital should read
  • Rapid fluctuations in temp reading on that probe.

Probably are set to Celsius. Reprogram to Fahrenheit. See Pilot’s Guide for programming information.

Check that if a bayonet or threaded adapter probe is installed, that it is screwed in tightly and the threads are clean in order to ground the factory probe. If adapter is not grounded well to engine, voltage will be applied to the adapter thermocouple junction and disrupt the EDM instrument.

•  Check that the EDM is grounded at the engine case(not in the instrument panel). Do not use panel ground, battery ground, or airframe ground. Airframe ground can vary from engine ground by 1/4v. This could cause the EDM to show too ‘High’ or ‘Low’,  EGT, CHT temps. Or show ‘Unsteady’ readings. If grounded to the panel, to check if this ground is OK, use a digital voltmeter to measure the difference between the EDM ground and the engine block ground. If the difference is greater than 0.5 volts with the alternator charging, then remove the EDM ground (black wire) from instrument panel and connect it directly to the engine block ground.

• Swap the ‘faulty’ EGT probes wire to the next cylinders ‘good’ probe.  Now since that ‘good’ probes wire is now off, fasten it to the ‘faulty’ probe. You just swap the wire, not the probes. Now turn on the EDM. Does the other ‘good’ EDM cylinder channel now behave in the same way – jumps up and down..?  Then it’s the probe. If not and the original ‘faulty’ cylinder is still behaving in the same way, (no change)-  then it could be a bad crimp or connection or instrument is bad.

• Check for a bent or recessed pin on the rear P2 EDM-700/800 connector. (P1 & P2 for the 760)

• Check crimps between probe and harness.

•  Check that the EDM is grounded at the engine case(not in the instrument panel). Do not use panel ground, battery ground, or airframe ground. Airframe ground can vary from engine ground by 1/4v. This could cause the EDM to show too ‘High’ or ‘Low’,  EGT, CHT temps. Or show ‘Unsteady’ readings. If grounded to the panel, to check if this ground is OK, use a digital voltmeter to measure the difference between the EDM ground and the engine block ground. If the difference is greater than 0.5 volts with the alternator charging, then remove the EDM ground (black wire) from instrument panel and connect it directly to the engine block ground.

• Check that leads are not shorted together on the harness or where the probes connect to the harness.

• Check if the probe may have been mounted in a slip joint. Probes are not under warranty when mounted on a slip joint.

Check if the EGT and CHT probe leads are reversed.

Probes should be 2-4″ from exhaust flange.

 

This is normal. Fuel and air distribution is not optimal at low power settings.

Loose connections at the eye terminal – tighten or replace terminals.

This is normal due to incomplete combustion causing the flame head to persist longer.

Make sure that the unit is grounded at the engine. If voltage difference is greater than 0.5 volts with the alternator charging then move ground to engine block.

EGT & CHT probe leads swapped. CHT too high to register.

Check CHT on that cylinder to see if may be bad cylinder. If the CHT is okay then proceed, otherwise the cylinder is likely bad.

•  Swap the ‘faulty’ probes wire to the next cylinders ‘good’ probe.  Now since that ‘good’ probes wire is now off, fasten it to the ‘faulty’ probe. You just swap the wire, not the probes. Now turn on the EDM and get up to operating temperature. Does the other ‘good’ EDM cylinder channel now behave in the same way – missing bar column?  Then it’s the probe. If not and the original ‘faulty’ cylinder is still behaving in the same way, (no change)-  then it could be a bad crimp or connection or instrument is bad.

• Check for a bent or recessed pin on the rear P2 connector.

• Check crimps between probe and harness on that particular EGT channel.

• Check that leads are not shorted together on the harness or where the probes connect to the harness.

Check for copper wire substituted for thermocouple wire

Reading should not be trusted. Check for loose wire crimp or bad probe.

Adapter probe not grounded or probe leads reversed.

  • Go to pilot program mode (Hold both buttons to see PROGRAM).
  • Tap STEP until you see EGT 1? N.
  • Tap LF to change to EGT 1? Y.
  • Tap STEP repeatedly to END Y.

Keep the distance from the cylinder head the same for each probe. 2 to 4 inches is recommended. Closer will shorten the life of the probes. Farther (up to 5 3/4″ inches) is okay. Uniform spacing is important. Temperature differences of 100° per inch can be expected.

Do not mount probe in a slip-joint. If you must mount in a slip joint, drill the inner stack hole oversize(3/8″) so that vibration won’t shear the probe. Outer stack hole: 1/8″. Probes sheared by slip-joints are NOT covered by waranty.

To calibrate the EDM-700/800/760 using the ‘factory’ TIT probe.

Parallel the conection. K type thermocouple – connect red to red and yellow to yellow. See your EDM-700/800 Install Manual Rpt #103 for documentation supporting this, or your Pilot’s Guide. Also Rpt # 760 for the EDM-760, or its Pilot’s Guide.

To calibrate the EDM:
1. Go to pilot program mode (Hold both buttons to see PROGRAM).
2.Tap STEP until you see RATE.
3. Hold both buttons until you see ORIG TIT … ORIGT-N.
4. Tap LF to change to ORIGT-Y.
5. See CAL TIT … TIT+0.
6. Tap or hold LF to change the correction factor (for example, if the EDM reads 100 less than the aircraft’s TIT, set the display to read TIT+100)
7. Tap STEP to exit.