Why do my rpms spike up when I start my car?
Common causes of high RPM excursion at start-up are typically: large vacuum leak, throttle plate stuck open, cruise control stepper motor stuck in one position; faulty throttle position sensor, and/or faulty idle air control motor or solenoid.
Why is my car surging at idle speed?
When an engine’s computer can “hunt” or “surge” at cruising or idle speeds it is searching for program compliance, there is a problem elsewhere in the system.
Why does my car idle high when I start it up?
On a carbureted engine, the fast idle screw sets the idle speed at a high rpm, like the name implies, to allow the vehicle to quickly warm up, while the choke is closed. If the fast idle screw is not tuned properly the vehicle’s engine will idle either too high or too low at start up.
When does idle come back to normal on a Harley Davidson?
Just seems to happen when I’ve been running at a fairly wide open throttle maintaining higher speeds for a while (fwy) or longer stints (catching all green lights) on the streets at a speed of about 45 or more. It always seems to come back to a normal idle after getting back into first gear when stopped, or when I start going again in 1st.
What to do when idle surges like crazy?
1. Warm up the engine completely. 2. Remove the intake boot at the front of the TB (throttle body). 3. Duct tape the big hole shut on the lower right hand corner in front of the TB plate/butterfly. Please make sure you clean where your gonna tape so the tape doesn’t get sucked in. 4. Connect the boot back.
When an engine’s computer can “hunt” or “surge” at cruising or idle speeds it is searching for program compliance, there is a problem elsewhere in the system.
How to troubleshoot an automotive engine high idle?
The troubleshooting procedure for high and low idle conditions are similar, which are included in the following: Step 1 – If the check engine or service engine light soon has illuminated retrieving the diagnostic trouble codes could lead you in the right direction of what the problem is, or is related too.
1. Warm up the engine completely. 2. Remove the intake boot at the front of the TB (throttle body). 3. Duct tape the big hole shut on the lower right hand corner in front of the TB plate/butterfly. Please make sure you clean where your gonna tape so the tape doesn’t get sucked in. 4. Connect the boot back.
What happens when engine idle speed is above programmed range?
When the engine idle speed is either above or below the programmed range, the ECU prompts the ISC to either increase or decrease bypass airflow. Naturally, as the IAC prompts the throttle plate to open, engine speed increases. The IAC features a plunger mechanism that may be stuck/sticking.