Header tube temp question.
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Fleet Mechanic
Joined: Oct 2025
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I used to inspect hazardous materials and explosives that flew on aircraft. When people wanted to argue more than once, I would tell them “Your inability to comprehend doesn’t dictate my accuracy!” I worked with a lot of true type A personalities.
Didn’t get to the plugs yesterday as the truck decided I needed a new battery instead. I did MAPP gas the intake and injectors with zero rpm difference. I know it’s not 100%, but that does narrow down some I think.
Didn’t get to the plugs yesterday as the truck decided I needed a new battery instead. I did MAPP gas the intake and injectors with zero rpm difference. I know it’s not 100%, but that does narrow down some I think.
Laughing Gas
Joined: Jul 2009
Posts: 1,026
Likes: 417
From: NE Ohio
A quick search of why ONE cylinder would have a higher EGT than another revealed this:
A single cylinder with a high Exhaust Gas Temperature (EGT) usually indicates an abnormal combustion event where the burn is slow or incomplete, leaving a hot charge to travel into the exhaust pipe. Common culprits include an ignition misfire, a clogged or failing fuel injector, or a leak in the intake or exhaust.
Verify Valve Sealing: A burnt or sticking exhaust valve can allow hot, pressurized combustion gases to escape into the exhaust manifold prematurely, causing a severe and immediate spike in EGT.
A single cylinder with a high Exhaust Gas Temperature (EGT) usually indicates an abnormal combustion event where the burn is slow or incomplete, leaving a hot charge to travel into the exhaust pipe. Common culprits include an ignition misfire, a clogged or failing fuel injector, or a leak in the intake or exhaust.
Verify Valve Sealing: A burnt or sticking exhaust valve can allow hot, pressurized combustion gases to escape into the exhaust manifold prematurely, causing a severe and immediate spike in EGT.
Thread Starter
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Fleet Mechanic
Joined: Oct 2025
Posts: 1,873
Likes: 408
A quick search of why ONE cylinder would have a higher EGT than another revealed this:
A single cylinder with a high Exhaust Gas Temperature (EGT) usually indicates an abnormal combustion event where the burn is slow or incomplete, leaving a hot charge to travel into the exhaust pipe. Common culprits include an ignition misfire, a clogged or failing fuel injector, or a leak in the intake or exhaust.
Verify Valve Sealing: A burnt or sticking exhaust valve can allow hot, pressurized combustion gases to escape into the exhaust manifold prematurely, causing a severe and immediate spike in EGT.
A single cylinder with a high Exhaust Gas Temperature (EGT) usually indicates an abnormal combustion event where the burn is slow or incomplete, leaving a hot charge to travel into the exhaust pipe. Common culprits include an ignition misfire, a clogged or failing fuel injector, or a leak in the intake or exhaust.
Verify Valve Sealing: A burnt or sticking exhaust valve can allow hot, pressurized combustion gases to escape into the exhaust manifold prematurely, causing a severe and immediate spike in EGT.
Last edited by 90project5.0; Jun 12, 2026 at 12:01 PM.
Laughing Gas
Joined: Jul 2009
Posts: 1,026
Likes: 417
From: NE Ohio
The gist is, A/F mixture can cause one cylinder to be different than another. hence looking at the injector in your 'problem' cylinder. Move that injector to another cylinder to ascertain if the problem follows the injector or not.
Logistics Pro
Joined: Aug 2010
Posts: 3,718
Likes: 586
From: Chillicothe
That cylinder could also be leaner than the rest. I.E. leaking intake gasket causing it to be hotter. If it is lean enough it will take longer to burn or not burn completely in the chamber and will take heat with it on the way out.
I learned this tuning carbs. The eye burning idle that most people think it rich, is actually partially unburned fuel because there was not enough oxygen in the mixture to burn it. So don't just assume it is a leaking injector causing this condition, it could be a partially clogged one too, or a vacuum leak.
I learned this tuning carbs. The eye burning idle that most people think it rich, is actually partially unburned fuel because there was not enough oxygen in the mixture to burn it. So don't just assume it is a leaking injector causing this condition, it could be a partially clogged one too, or a vacuum leak.
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Fleet Mechanic
Joined: Oct 2025
Posts: 1,873
Likes: 408
That cylinder could also be leaner than the rest. I.E. leaking intake gasket causing it to be hotter. If it is lean enough it will take longer to burn or not burn completely in the chamber and will take heat with it on the way out.
I learned this tuning carbs. The eye burning idle that most people think it rich, is actually partially unburned fuel because there was not enough oxygen in the mixture to burn it. So don't just assume it is a leaking injector causing this condition, it could be a partially clogged one too, or a vacuum leak.
I learned this tuning carbs. The eye burning idle that most people think it rich, is actually partially unburned fuel because there was not enough oxygen in the mixture to burn it. So don't just assume it is a leaking injector causing this condition, it could be a partially clogged one too, or a vacuum leak.
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