Understanding Engine Vacuum and MAP - What is Vacuum? Why engines have vacuum & why it's important

Подписаться 2,7 тыс.

Просмотров 3,4 тыс.

50% 1

Gasoline engines with throttles develop vacuum in the intake manifold. That vacuum provides information about how the engine is running and can be used to diagnose problems.
So what is vacuum, why does an engine have vacuum and how is it measured? What causes it to be high or low, what is normal? What is MAP and how does it relate to vacuum?
DISCLAIMER: In my videos and written or text comments, I provide demonstrations, suggestions, and opinions on techniques, methods, and materials for various projects. While I try to be accurate, there are no guarantees, expressed or implied, that my information is correct and will work for you. If you wish to use any of this information, you must check and verify that it is appropriate for your use - use it at your risk. Do-it-yourself projects are variable and there are risks in conducting them.

Опубликовано:

29 сен 2024

Ссылка:

Скачать:

Готовим ссылку...

Добавить в:

Мой плейлист

Посмотреть позже

Комментарии : 18

@budsodalsky 4 месяца назад

Thank you for this - when i was a kid i wondered why people had accesory vacuum gauges installed on their dash. Lol "What's it good for" in pirate voice.

@bitsofwisdom460 4 месяца назад

Yes, that is why. They were popular, especially when gas was in short supply.

@mikebruegger8654 4 месяца назад

Great in depth training for lots of us. Thnx!

@PlanetTwilow 3 месяца назад

We are standing on the bottom of an ocean of air that covers the planet Earth. The weight of the 100 miles of air above us, is 14.7 Lbs. Air weighs a lot less than water, don't try this at the bottom of the Pacific.

@EricKiltie 19 дней назад

Great video - thanks.👍

@DadsGarageDiagnosticSpecialist 4 месяца назад

This is premium content. A goldmine of knowledge.

@aidan9958 11 дней назад

Could this explain why the oil filler hole/dipstick tube pulsates air in and out during idle? I understand there's PCV connected to the crankcase, but I was a bit alarmed by how much air appeared to be coming out of the oil filler hole during idle. If I placed a sheet of paper of the hole, it would rapidly push and pull the paper to the hole as if it was "pulsating" Or is this just air displacement within the crankcase from the pistons moving up and down at a rapid rate..

@bitsofwisdom460 7 дней назад

There can be some pulsating, but most of the pulsation (in most engines with even number of cylinders) should be neutral because as a piston moves down, another moves up. There will be some net flow outward due to the "blowby" or leakage of combustion gasses past the rings. If you have a cylinder with higher leakage you might get a stronger outward pulse when it fires. The entire intent of PVC is to pull these vapors and burn them.

@TaylorJensen-ys2cv Месяц назад

Man I hate it when people know what they are talking about, leaves nothing for me to criticize........... this is one of those over look thing today, I think if more people really understood how vacuum is used in Modern EFI and it's affects on intake draw and Injectors, there would be a lot of really good tuners out there.

@bitsofwisdom460 Месяц назад

Thank you, and I agree that vacuum or manifold pressure is often not understood. When I was working in the hybrid vehicle world, our calibrators had to watch manifold pressure very carefully. A particular example was that if you wanted a smooth restart while you had been running in a hybrid mode with the engine off, it was best to spin the engine with the throttle closed and the fuel off until the intake manifold pressure pumped down to the right pressure / vacuum. Then you could fuel the engine and not have a big spike in torque due to all the air in the intake. It made for very smooth restarts.

@jimknowlton342 4 месяца назад

Thank you so much!

@bitsofwisdom460 4 месяца назад

You're welcome!

@ernestdamo677 19 дней назад

Thanks for the knowledge you have provided, please what does late ignition timing means

@bitsofwisdom460 17 дней назад

Late ignition timing is a little variable. In general, engines like to have a base timing several degrees before top dead center. Depending on the design it can be from perhaps 5 degrees before TDC up to as much as 15 degrees. If the timing is much lower than that, then vacuum would be lower and would be considered late timing. It might even be AFTER TDC. When I say it is variable, if an engine should be set to 10 BTDC and it's running at 2 BTDC, it would be late.

@ernestdamo677 17 дней назад

@@bitsofwisdom460 thanks