What Causes Rough Idle In My Car

rough idle speedI have a 323 Mazda at present I have a problem with idle speed. When I start the car it is idling good. When I put it into drive the gear, after driving for (5) minutes the engine is racing and the gears is not changing,the car will lost power and cut off.

Then I will restart the car after (10) minutes I will put it into drive gear,after driving for (5) minutes the same will happen

Can you please assist me with your knowledge.
Thanks in advance

Hello back Patrick

Hummm interesting. I think I would first look under the good to see if there is a vacuum leak somewhere, like from the air cleaner to the engine…that large black hose. Do you see a hole in it, or can you hear a sucking noise coming from it with the engine running in park?

Rub your hand along the hose, underneath and at the connection to the air cleaner box and at the engine where it attaches to the throttle body. It’s pretty common for the fast oil change guys to not reinstall the air cleaner box or leave the hose loose after they try and sell you a new air filter 🙂

If you have a broken motor or transmission mount, it will allow the engine to move up and down and could have plugged apart that hose or it’s connections.

You might be able to see if there is excess movement in the engine by having someone inside the car place the transmission in drive and also reverse then with one foot on brake slowly bring up the engine speed with the accelerator.

If the engine moves more than an inch, your motor mounts are probably bad…watch the black hose as this happens and any other rubber hoses to see if they cause an air leak/vacuum leak.

Next thing I would look at is the throttle body, and does it need to be cleaned. Remove the large fresh air hose that is attached to the engine and look inside the throttle body for dirt and grime.

Watch my video below and see how easy it is to clean it yourself. You just need some intake cleaner spray and a hard brush, like a tooth brush or a small metal brush and a rag.

Please share this with your friends
Austin Davis

Posted in: Running Problems

4 Comments on "What Causes Rough Idle In My Car"

Trackback | Comments RSS Feed

  1. jule says:

    thank you, this was very helpful. keep it up

  2. Gomez says:

    You are the man. I found a vacuum leak in the exact same hose you talked about from the air cleaner to my engine. I never would have thought about that or ever even looked at that. owe ya one brother.

Got Something to Say?