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No.1 CHT and EGT lagging and low

Derek

Active Member
Ive recently run and flown my engine (and aircraft) for the first time, the engine was pickled for 2 years.It's a zero timed 0-360 A4M converted to AFP's FI. What was noticable immediately was No.1's CHT and EGT was the last of all the 4 cylinders to rise, way behind the other three and significantly lower in temperature. In the first picture Ive attached you can see that on initial start-up No.1's CHT is 70 degrees lower than all the rest, and you can see that this trend continues in the next photo taken approximately 13 minutes later.

Also No.1 cylinder is fouling the plug during extended periods of idling on the ground, however this can be cleared by leaning.

Lastly....what's noticable after running WOT on the ground then pulling back to idle No1's EGT falls away noticably quicker than the other 3 cylinders.

Is what im experiencing the symptons of a new engine and will settle down once run in or should I be concerned ?




 
I see that you have let your CHTs go above 400 deg. During your break in period you should alway keep them under 400. Preferably under 380! Keep your ground run ups to a minimum duration. Don't be concerned with your EGTs until you get it broken in. The CHTS will also come down when you get it broken in. I would suspect this will take 10-30 hours depending on how well you maintain the breakin profile called out in the LYCOMING manual. After breakin you can look at equalizing your CHTs using the front air dams, further baffle sealing, etc. you can also flow match the cylinders after break in. Don't worry about the individual EGTs for now. This could be caused by probe calibration or location in the exhaust tube.
 
Given the fouling, its possible that your #1 is excessively rich. When does it peak compared to the others when leaning?
 
Flow problems

Given the fouling, its possible that your #1 is excessively rich. When does it peak compared to the others when leaning?

Check the spread on leaning. Possible fuel flow to #1 is way off the other three. I had the same problem and had to return my flow divider to fix it.
 
Is this the process ?

Given the fouling, its possible that your #1 is excessively rich. When does it peak compared to the others when leaning?

Thanks for you reply, newbie question just to be sure.

Do I lean progressivly on the ground ( making sure I dont exceed 380 degrees F CHT) and then compare where No.1's CHT is to the other 3 ?
 
Thanks Bill

I see that you have let your CHTs go above 400 deg. During your break in period you should alway keep them under 400. Preferably under 380! Keep your ground run ups to a minimum duration. Don't be concerned with your EGTs until you get it broken in. The CHTS will also come down when you get it broken in. I would suspect this will take 10-30 hours depending on how well you maintain the breakin profile called out in the LYCOMING manual. After breakin you can look at equalizing your CHTs using the front air dams, further baffle sealing, etc. you can also flow match the cylinders after break in. Don't worry about the individual EGTs for now. This could be caused by probe calibration or location in the exhaust tube.

I'll watch the max CHT more closely whilst ground running.
 
Thanks JD

Check the spread on leaning. Possible fuel flow to #1 is way off the other three. I had the same problem and had to return my flow divider to fix it.

Ive been told of a method to check the flow divider is to run the boost pump and capture then measure the amount of fuel being delivered at each of the injectors, this will indicate if the flow divider is functioning correctly. To me this sounds like an simple test, just wondering if anyone has done this ?
 
Thanks for you reply, newbie question just to be sure.

Do I lean progressivly on the ground ( making sure I dont exceed 380 degrees F CHT) and then compare where No.1's CHT is to the other 3 ?

Do not be afraid of the red knob. Go fly, keep MP below 24", check to see when all 4 EGT's peak. Check the difference in the fuel flow between the first to peak and the last. Use your efis to record.
 
Ive been told of a method to check the flow divider is to run the boost pump and capture then measure the amount of fuel being delivered at each of the injectors, this will indicate if the flow divider is functioning correctly. To me this sounds like an simple test, just wondering if anyone has done this ?

This is sometimes called the coke bottle test. Loosen all tubing clamps, remove injector #1 and at least one other, direct injectors into clear containers like coke bottles. Mixture full forward, turn on electric fuel pump until easy to see fuel is collected. Compare bottles, does bottle #1 have more gas than others?
 
Derek,

You need to do a lot of things.....call me ASAP. I reckon also start booking your airline tickets to Perth for Friday the 16th of May returning Sunday night.

Check your PM's
 
Injectors?

I just had an interesting conversation a few days ago with an RV-7A owner with a fuel injected Superior Engine. He told me a story about how he was on a cross country with another RV pilot with the same engine and the same amount of fuel on departure. When they stopped to refuel he discovered that had to put in about 9 more gallons of fuel than the other pilot, and he could not figure out why.

The investigation later revealed that a sleeve on one of the injectors was missing, and was allowing much larger quantities of fuel into that cylinder as a result. Apparently it was missed during assembly of the injectors. Not saying that is your specific problem, but perhaps this is something else to consider......
 
Thanks Bob

This is sometimes called the coke bottle test. Loosen all tubing clamps, remove injector #1 and at least one other, direct injectors into clear containers like coke bottles. Mixture full forward, turn on electric fuel pump until easy to see fuel is collected. Compare bottles, does bottle #1 have more gas than others?

The test sounds simple enough, I'll give it a go.
 
Thanks Bryan

I just had an interesting conversation a few days ago with an RV-7A owner with a fuel injected Superior Engine. He told me a story about how he was on a cross country with another RV pilot with the same engine and the same amount of fuel on departure. When they stopped to refuel he discovered that had to put in about 9 more gallons of fuel than the other pilot, and he could not figure out why.

The investigation later revealed that a sleeve on one of the injectors was missing, and was allowing much larger quantities of fuel into that cylinder as a result. Apparently it was missed during assembly of the injectors. Not saying that is your specific problem, but perhaps this is something else to consider......

Sounds like a simple check, I can do this at the same time Im checking the fuel flow.
 
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