Build up on spark plugs?

Hi,

Wow, that is a mess. Is that carbon? Also, you don't need a scan tool to retrieve codes from this vehicle. All you need is a short jumper wire or even a paper clip.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Let me know what codes you find. Also, even if the engine light isn't on, there could be codes on this system.

When the truck is running, do you feel the misfire? Also, if you haven't already, you may want to check compression in that cylinder. It looks like it is carbon fouled.

A spark plug can become carbon fouled when deposits of carbon build up on its firing end. This build-up occurs due to incomplete combustion of fuel, oil, or other contaminants in the combustion chamber. Several factors can contribute to carbon fouling:

--Rich Air-Fuel Mixture: If the air-fuel mixture in the combustion chamber is too rich (contains excess fuel), the combustion process may not be efficient. Incomplete combustion leads to the formation of carbon deposits on the spark plug.

--Oil Consumption: If the engine is burning oil, either due to worn piston rings or valve seals, the oil can enter the combustion chamber and contribute to carbon fouling. The oil burns along with the fuel, leaving behind carbon deposits on the spark plug.

--Short Trips or Idle Time: Engines tend to operate at lower temperatures during short trips or extended periods of idling. In such conditions, the combustion process may not reach its optimal temperature, leading to carbon fouling on the spark plug.

--Low-Quality Fuel: Poor-quality or contaminated fuel can contain additives or impurities that contribute to carbon fouling. These substances can leave deposits on the spark plug, hindering its performance.

--Defective Ignition System: Issues with the ignition system, such as a weak spark or improper timing, can result in incomplete combustion and carbon fouling.

--Old or Worn Spark Plug: Over time, the spark plug electrodes can wear out or become covered in deposits, reducing their ability to produce a strong spark. This can lead to incomplete combustion and carbon fouling.

Let me know if you find codes and if any of the possible causes, I listed make sense for this case.

Take care,

Joe

Hi,

The borescope is a great idea. As far as removing the valve cover is concerned, that won't tell us anything because you can't see the actual valve.

I have a feeling we have a fuel pressure issue. If you are comfortable, I would test the pressure and the pressure regulator. The fuel pressure is part of the fuel meter cover assembly. It isn't serviceable. Actually, there are four screws that hold it in place, but don't remove them. There is a very strong spring behind them.

Do you ever notice a rich fuel smell when it's running or black/dark gray smoke from the exhaust? A rich or lean fuel mixture can cause a backfire.

Take a look at this link:

https://www.2carpros.com/articles/engine-backfires-while-running

Because there is a backfiring issue, my theory at this point is the engine is getting too much fuel at this point and washing junk into the cylinder. Please understand I could be wrong. This is only a theory.

Let me know.

Joe