Q: Missing IAC valve vacuum line.

asked by on

I recently redone my vacuum lines and noticed a small port on my IAC valve that while open caused some hesitation in the engine but after capping it off the engine runs alot smoother, even during shifting gears. My vacuum lines seem to have a T-splitter near this area and I was wondering if this was an indication that the IAC was meant to have one of the lines from my Carbon filter box run to it instead of having it capped off.

My car has 187000 miles.
My car has a manual transmission.

The IAC (Idle Air Control) valve is required to have a vacuum line on it to work the engine properly. The line from the carbon box filter is supposed to be hooked to it, but it may be damaged. Take the hose on the carbon box filter and suck on it to see if it holds a vacuum. If it does, then I suggest hooking up the hose to the IAC. If it does not, then I recommend replacing the carbon box filter and then hooking up the vacuum hose to the IAC. If you need further assistance with your vacuum lines disconnected, then seek out a professional, such as one from Your Mechanic, to help you.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Missing IAC valve vacuum line.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Truck is overheating - 1992 Chevrolet C1500

There are a few things to check over. The water pump produces flow. To check this remove one of the heater hoses (small diameter) going to the heater core. Locate the hose end to a container to check flow of...

Q: Q: Engine will turn over but will not start.

Hello there, many common faults will cause your 1985 Ford F-250 to crank but not start. You have done great so far in inspecting the vehicle and changing the spark plug wires, fuel pumps, and filters. There are a few...

Q: Vacuum hose unhooked brake - 1990 Dodge D150

Hello. The vacuum hose from the brake booster goes into a tube on the intake. This tube is going to be about the same diameter as the hose and may need a clamp to secure it properly. The small vacuum...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...