Why does my Honda idle speed go up and down?

Why does my Honda idle speed go up and down?

A customer’s Honda runs perfectly fine when the engine is cold, but then develops a weird surge condition after it’s warmed up. For no obvious reason, the idle speed fluctuates steadily up and down. Assuming that the cooling system is up to snuff, this is a classic symptom of a failed fast-idle valve on a fuel-injected Honda.

How does the Honda fast idle thermo valve work?

Dan explains how Honda’s fast-idle valve works, the symptoms you’ll encounter when it doesn’t and how you can home in on diagnosing a leaker. A customer’s Honda runs perfectly fine when the engine is cold, but then develops a weird surge condition after it’s warmed up. For no obvious reason, the idle speed fluctuates steadily up and down.

What to do if your car is idling too fast?

A throttle body cleaning is likely to cure the high idle speed as well. There are many possibilities when your engine is idling too fast. Here are some common ones to help guide you towards the root of the problem.

What to do if your Honda Civic Idles up?

Just pump your Gas Pedal a few times if you have ” Cold Starting Issues “…. But once your Engine is Warm / Hot, Idle will be ” NORMAL ” again. NOTE: That is the only ” DOWN FALL ” to this Bypass. B. Block Off By-Pass – You can make a Gasket and ” Block ” the 2 holes on your IACV and put the IACV back. It will ” NOT ” harm anything.

A customer’s Honda runs perfectly fine when the engine is cold, but then develops a weird surge condition after it’s warmed up. For no obvious reason, the idle speed fluctuates steadily up and down. Assuming that the cooling system is up to snuff, this is a classic symptom of a failed fast-idle valve on a fuel-injected Honda.

Dan explains how Honda’s fast-idle valve works, the symptoms you’ll encounter when it doesn’t and how you can home in on diagnosing a leaker. A customer’s Honda runs perfectly fine when the engine is cold, but then develops a weird surge condition after it’s warmed up. For no obvious reason, the idle speed fluctuates steadily up and down.

Just pump your Gas Pedal a few times if you have ” Cold Starting Issues “…. But once your Engine is Warm / Hot, Idle will be ” NORMAL ” again. NOTE: That is the only ” DOWN FALL ” to this Bypass. B. Block Off By-Pass – You can make a Gasket and ” Block ” the 2 holes on your IACV and put the IACV back. It will ” NOT ” harm anything.

How can I tell if my Honda is running a cold engine?

If this were the case, a cold engine would start and promptly stall. You can quickly check valve operation by removing two screws and pulling the cover off the top of the valve. When a cold engine is running, you should feel suction at the tip of the air bypass valve.

Why does my car idle when it is warm?

When the cars idle gets rough, it hard to comprehend the related causes. It is because rough idle when warm can either be caused by one faulty component or through series of problems. Hence, after knowing the ways to troubleshoot rough idle when warm problem, anyone can now keep a check on their vehicle’s status.

Is there a problem with rough idle when warm up?

So, once there’re visible signs of rough idling, trouableshoot the problem without causing any further delay. As reported by Car From Japan experts, most Makes getting this engine rough idle after warm up are: Though the problem is not common but drivers of the Makes had their car serviced at garages for Rough Idle When Warm.

What causes idle surge on a Honda Accord?

When the valve fails, it causes idle surge. Here’s how to check it out. 1) Start by making sure the cooling system is filled with coolant and there’s no air in the system. If it’s low on coolant, that can trick the fast idle valve.

How to test the fast idle valve on a Honda?

3) Once the engine coolant is above 90 degrees F, you can proceed to test the fast idle valve. Start the engine and remove the vacuum line on the lower portion of the throttle body. Check for vacuum. There should be NONE.

What causes fast idle thermo valve to not close?

By far the most common problem is a valve that won’t close after the engine warms up. In the early stages of this failure, a sluggish fast-idle valve may cause a surging symptom only when the engine is partially warmed up.