EGT indication

hydroguy2 · #1 07-26-2012, 11:52 AM

On our trip home yesterday, I saw #1 EGT was jumping around, when normally all 4 track closely together and <30*f spread. It was running about 1295-1300, but would dip to 1100, then 1380, 1250, then be normal for a while before bouncing around. I saw ranges from 1000, 1400....others normal and steady. During this CHT was 350 or so and steady.

I chalked it up to a failing probe and just kept tabs on it, but basically ignored it for the time being. SOme times to much info can over ride common sense. So, a few hours later a minute stumble caught my attention and I saw the CHT drop to 300 or so and come right back up. I was running lean so thought maybe too lean. a little richening and went on about our merry way.

80 miles out, at 12500' DA was 14700 or so, the engine stumbled pretty good. I went to the rich side and was on high alert. CHT appeared lower than normal, I usually only have a 15* spread now 20-25. EGT still bouncing around. During the descent, I get the typical engine popping(I actually enjoy the music out of a 4 pipe). But ran good and mag check while taxiing in was good also.

SO...clogged injector? loose intake boot? cylinder dieing?

where do I start?

Mike S · #2 07-26-2012, 12:00 PM

Was this the same cyl that had the broken exhaust pipe??

JonJay · #3 07-26-2012, 12:10 PM

I had a similar issue for some time. We then discovered that an exhaust valve was not stuck, but hanging up from time to time. Do a comp. check on #2. It may or may not show up like mine as it was an intermittent "sticking".
The other thing to look for is on start up, when the engine is cold, is number two EGT's lower than the rest or did it change from where you knew it was before.
By the way, mine tended to show up when at altitude and leaned. Enrichment always "cured" the condition.
We refrub. the cylinder and all has been well since.
Good luck.

hydroguy2 · #4 07-26-2012, 02:07 PM

Mike, different cylinder than the busted exhaust.

I'm due for an oil change in the next hour or two, so will do a comp check that day. Enriching seemed to make things better, but still had fluctuations. I'll download the EMS data this weekend.

RV10inOz · #5 07-26-2012, 09:09 PM

Did you try a mg check hole you were LOP? This is the time to do them.

Do a GAMI lean test t altitude and then lower much lower, but set the same MP, compare the result.

A falling CHT suggests less HP being produced so on the lean side TIS could well be an induction leak.

Should I ask, what are you doing on the 19-21 of October?

BobTurner · #6 07-26-2012, 10:44 PM

Swap EGT probes, see what happens.

hydroguy2 · #7 07-27-2012, 08:51 AM

Quote:

Originally Posted by RV10inOz

Did you try a mg check hole you were LOP? This is the time to do them.

Do a GAMI lean test t altitude and then lower much lower, but set the same MP, compare the result.

A falling CHT suggests less HP being produced so on the lean side TIS could well be an induction leak.

Should I ask, what are you doing on the 19-21 of October?

I didn't do a mag check. The engine was purring along nicely , with exception of 2-3 hesitations or stumbles. So being full of camping gear and my nervous to fly wife sitting in the right seat, I chose to minimze the trouble shooting. I only saw the CHT dip one time. As I descended from 12500, EGT appeared to stabilize. But to be fair I wasn't watching all that close, prepping for landing. Oil change time next week, so will go do some tests while warming up the engine.

I'll be working in October...every weekend.

RV10inOz · #8 07-27-2012, 10:57 PM

Inlet gaskets are worth checking.