JPM 700 doesn't match saratoga digital engine TIT

Jon Hamilton

Just flew to new to me 98 saratoga from Iowa to Tulsa. Enroute I observed the JPM 700 indicating 75 degrees hotter than the steam gauge and digital readout. This made quite the difference in my fuel flow and not sure how to differentiate which is incorrect?

Bob H

Hi Jon,
The TIT probe should bee installed in the Exhaust Stack Accumulator at 2-4 inches from the turbine inlet at a depth of 2 1/2 inches. Make sure that the probe to the JPI is in that location and installed per that spec. The Saratoga gauge will obviously not be in that same location and is likely to read differently. The JPI is probably the more accurate instrument and deserves the better probe location. Ignore the other instrument! Why the FAA insists you keep a less accurate gauge in the aircraft when you install a better
engine monitoring tool defies logic sometimes? Good Luck! Bob Hart www.AvionixHelp.com

m.cusumano@hotmail.com

I have the exact same problem in my 1999 Piper Saratoga II HP. Does your model year have the DDMP which digitizes all the analogue gauge information? I think 1999 is the first year to have it. (your better off without it...it fails every 5 or 6 years due to the CMOS battery going bad, which remembers the date, and it won't work without it. It costs 2800 to fix it). Anyhow, I have a very expensive Digital engine monitor, in addition to the DDMP, and I used to use it all the time, but now I just go off the stock probe's EGT and CHT information. I do check the JPM unit from time to time, but for normal leaning purposes, I find its just easier to use the stock readouts....