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EGT Changes Recently

istrumit

Well Known Member
Hello -

My EGT on #2 has always (since I have owned the plane) been the lowest EGT on my Fuel Injected 540.

The last two flights, it went form being the lowest, by 30F to the highest by 30F. A total change of about 100F

Basically, without any trend whatsoever from flight to flight, it when from around 1350 F to around 1450F. All flights prior, its the lowest, and then, last three flights, its the highest.

Looking at the data, it seems to not to respond to fuel flow like the other cylinders do. Meaning, moving from rich to lean or vice versa, Cyl #2 EGT stays someone steady while the other Cylinders move down and up.

Dr. Google says that that its a bad wire or fouled plug, but, my run up is smooth as silk and the engine seems very very smooth.

I have no idea what to make of this.

Advice ?
 
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This happened in my Beech. It was an exhaust leak - the hot gasses were heating up the cylinder. Worth a quick check.
 
Instrument error or a change in delivered air/fuel ratio. If this is a carbureted 540, look at the intake tube gasket.
 
Intake leak?

Have you tried leaning to see if the peak EGT across the engine has changed? Perhaps you have an intake leak on that cylinder.
 
That or a clogged injector. Confirm by looking at a higher CHT (if ROP) or lower CHT (if LOP) from your previous experience. You can also confirm by doing a data run and record fuel flow when each cylinder peaks. A cylinder with a clogged injector will peak early compared to the others.

Carl
 
Instrument error or a change in delivered air/fuel ratio. If this is a carbureted 540, look at the intake tube gasket.

Its fuel injected....I did check the intake manifold gasket and it was in bad shape, so I replaced it.

But, the EGT variance did not improve.
 
Its really weird. Looking back through the data from a month or so ago, when it was still the lowest temp, I see an instance where #2 got hotter while all other Cylinders got cooler while in a decent.

That sounds like an intake leak, but I replaced that gasket already with no improvement.

#2 is higher by a significantly margin than all others.
 
....Swap the temp probe and see if it follows? :rolleyes:

Yes, and another easy thing to do would be to remove the restrictor nozzle for number 2 and inspect it under a loop or magnifying glass. Blow compressed air backwards through it and replace.
 
Its fuel injected....I did check the intake manifold gasket and it was in bad shape, so I replaced it.

But, the EGT variance did not improve.

But did you check the EGT peak spread while leaning? A large change points to nozzle clog or induction leak
 
But did you check the EGT peak spread while leaning? A large change points to nozzle clog or induction leak

I have not done that, no.

I plan on some data collection on my next flight.

But, here is a twist.

I just looked back through about 20 flights of data and in at least three other flights, the EGT on #2 was high compared to the rest.

While on the rest of the flights, it was the lowest.

So, out of about 20 flights, in 75% of them #2 is the lowest EGT by a good margin, and on 25% of the flights is the highest by a good margin.

I have only just now noticed this and I don't understand it at all.
 
Check the injector as someone mentioned. On your next flight when you pull the throttle back to idle while airborne watch the EGT. If it rises you have an intake leak on that cylinder. I know you changed the gasket, but did you check the intake tube hoses at the other end of the tube? They are cheap to replace and do leak.

Vic
 
Check the injector as someone mentioned. On your next flight when you pull the throttle back to idle while airborne watch the EGT. If it rises you have an intake leak on that cylinder. I know you changed the gasket, but did you check the intake tube hoses at the other end of the tube? They are cheap to replace and do leak.

Vic

OK...I will try that this weekend...along with the mag check.

Makes no sense to me that it can flip from coldest to hottest from one flight to the next...I dont really care whether its a sensor, or a leak, or an injector...I just want to find it...I hate anomalies.

Interestingly, I should point out in the interest of journalistic integrity, that the CHT reading on the same cylinder was failing...meaning, actually x-ing out on the display...then, last weekend I removed it, tightened it...etc....NOW, it reads, but it reads a little low and oscillates by about 10-15 degrees.

I really feel like the CHT probe is bad and this is coincidental, but, maybe not.

When the CHT probe was not anomalous, back when I first got the airplane, it was always steady and in pretty much matched #1 in all phases of flight..but, after a bumpy (so so) landing, it became intermittent.

Now its part of the overall measurement weirdness of #2
 
Inconsistency like that doesn't make any sense as far as fuel flow. The fuel distribution unit doesn't regulate to each cylinder. If #2 had a clogged injector or air-induction leak, #2 would run lean all the time. I like Alan's idea of swapping the wiring from the EGT sensor on #2 with say #4 and see if the indicated problem travels to #4. This method is 1st go-to when looking at JPI's troubleshooting section when getting "strange" readings for EGT's. Been there.
 
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We had something almost the same a few weeks ago. Cleaned the injector and it went back to normal. It's quick and easy to do so no reason not to.
G
 
But did you check the EGT peak spread while leaning? A large change points to nozzle clog or induction leak

Any one know the socket size I need for checking the plugs ? and what tools are needed for removing the injector ?
 
Any one know the socket size I need for checking the plugs ? and what tools are needed for removing the injector ?

NVM on the tool request...its not plugs or injector.

Mag check on the ground showed all CYL rising EGT together...no one CYL was out of line.

Mag check in flight showed the same thing.

EGT in flight at low MP showed #2 slightly higher than the others, but not at high MP...at high MP, everything was pretty in line.

So, I am going with a small intake leak on #2.

Side note: CHT 2 has been glitchy. This time it was good until landing, then it failed low...then failed high...then failed low again. Its toast.

I will tighten the intake when I put on the new CHT probe (on order).
 
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