Symptoms of a Bad or Failing Automatic Timing Advance Unit

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Automatic timing advance units are a component commonly found on many vehicles equipped with carburetors, as well as vehicles equipped with diesel engines. Their purpose is to automatically adjust the timing according to the operating conditions.

Most automatic timing advance units are mechanical in nature and operate using centrifugal force to automatically advance the timing. This allows for a more dynamic engine power band as well as a more efficient operating engine. For diesel engines in particular, the automatic timing advance unit plays an even more significant role, due to the difference in combustion process in comparison to a gasoline engine. When the automatic timing advance unit fails it can cause a variety of problems that can disturb the performance of the engine. Usually, when there is an issue with the automatic timing advance unit, the vehicle will display a few symptoms that can alert the driver of a potential problem that should be serviced.

1. Engine knock

One of the earliest symptoms of a problem with the automatic timing advance unit is engine knock. Engine knock occurs when the air-fuel mixture is ignited before the optimum timing, causing uneven combustion to occur.

Uneven combustion can cause engine knock, which in turn can cause permanent damage to the engine if left unchecked. This symptom may be even more pronounced with diesel engines, where the ignition relies entirely on combustion pressure to ignite the fuel mixture. Engine ping or knock can be heard as an audible pinging or knocking noise coming from the engine.

2. Sluggish performance

Another symptom of a problem with the automatic timing advance unit is sluggish engine performance. The timing advance unit is designed to automatically advance the ignition timing to achieve better performance and efficiency from the engine. If it fails, the engine’s timing curve will be changed which can negatively affect the performance of the engine. In more serious cases, the engine may experience a noticeable loss in power, acceleration, and fuel efficiency.

3. Excessive black smoke

Another symptom of a problem with the automatic timing advance unit, one more specific to diesel engines, is excessive black smoke from the tailpipe. The timing on diesel engines is much more complicated to set due to the fact that there is no ignition system on a diesel engine and it relies solely on fuel pressure and cylinder compression to ignite the mixture. For this reason, a problem with the timing advance unit can quickly cause problems that can upset the the combustion process. Usually, the combustion will be incomplete, and the excessive fuel will be burned inside of the vehicle’s exhaust producing black smoke.

The automatic timing advance is an important component that is critical to the ignition timing and performance of an engine. For this reason, if you suspect that there may be a problem with it, have the vehicle diagnosed by a professional technician, such as one from YourMechanic. They will be able to determine if the vehicle needs an automatic timing advance unit replacement, or if another repair needs to be made.


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Bernie

50 years of experience
41 reviews
Bernie
50 years of experience
Honda Accord - Brake Pads Replacement (Rear) - Phoenixville, Pennsylvania
I specifically asked for Bernie to come back, since I was so pleased with the work he did on our other car. This time I got to meet Bernie personally. He is a kind family-man who exhibited the quiet confidence of someone you would expect with the 50 years of automotive experience that he has. I felt very comfortable giving him the key to my car. Two of my kids (ages two and four) came out to greet him, since they remembered him from his first visit. Bernie is great around kids and was very kind to my two-year old son who was trying to "help" Bernie do his job. Thanks again, Bernie!
Honda Odyssey - Brake Pads Replacement (Front, Rear) - Phoenixville, Pennsylvania
I was very pleased with Bernie's work, professionalism, and courteousness. Best brake job I have ever had, and I have had many done (and several done myself, but not on this vehicle). This was a maintenance appointment -- not a repair of something broken -- so I was surprised when the brakes felt so much better after Bernie did the work. You can really see the care he took with our vehicle when I examined everything after he was finished. Thanks, Bernie!

Daniel

9 years of experience
17 reviews
Daniel
9 years of experience
Hyundai Sonata - Brake Pads Replacement (Front, Rear) - Sacramento, California
Awesome customer service. On time and answered my questions with patience. Listened to my concerns and made helpful suggestions. Seemed very knowledgeable and experienced. I will be glad to request him again. Thank you!!

Breck

18 years of experience
532 reviews
Breck
18 years of experience
Toyota RAV4 - Brake Pads Replacement (Rear) - Conroe, Texas
Breck was awesome! He called ahead of time and asked if he could arrive early. He was friendly and easy to talk to. He made me feel comfortable with the service he was going to provide and explained things clearly to me. He smiled and made this experience a good one. I will absolutely be booking future appointments with Breck and I will recommend him and Your Mechanic services to others I know. Thank you!

Brian

19 years of experience
101 reviews
Brian
19 years of experience
BMW Z4 - Brake Pads Replacement (Rear) - Phoenix, Arizona
Brian knows what he is doing and I am so happy yourmechanic.com suggested him for my Z4 car inspection prior to purchasing and even happier he was available to perform my 1st service on the vehicle I purchased. His knowledge on the brand gave him ability to to an in depth inspection and he communicated very well informing me what to prepare for in ownership of my BMW. When he came to perform maintenance on my vehicle he shared so many tips with me. I will absolutely be having Brian come back out when I need future servicing on my car.

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