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sprinkles08, ASE Certified Technician
Category: Car
Satisfied Customers: 21807
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I have an issue at times when the car is at idle rev up then

Customer Question

I have an issue at times when the car is at idle rev up then almost dying.
JA: How many miles are on the car? What size is the engine?
Customer: around 74,000
JA: Tell me a bit more about what's going on so he can help you best.
Customer: When the car is warm and at idle it is like it is missing. The idle will bounce up and down. And has died once. Started up right away, if I rev it slightly it is fine till I let off the gas.
JA: Are you hoping to fix this yourself?
Customer: Yes
JA: Great! What have you tried so far?
Customer: I have only ran injector cleaner, through it a couple times, which seems to help for a while then back to the same problem. I run premium gas which helps instead of the mid grade.
JA: Is there anything else important you think the Mechanic should know about your car?
Customer: Not that I can think of.
JA: OK. Got it. I'm sending you to a secure page on JustAnswer so you can place the $5 fully-refundable deposit now. While you're filling out that form, I'll tell the Mechanic about your situation and then connect you two.
Submitted: 7 months ago.
Category: Car
Expert:  sprinkles08 replied 7 months ago.

Hello and welcome to JustAnswer!

There are many things that can cause an idle fluctuation, especially depending on what the vehicle is. No vehicle information was posted with the question, but an erratic throttle position sensor signal is a common cause of an idle fluctuation.

What year and model is the vehicle and what engine do you have?
Have you checked for fault codes?

Customer: replied 7 months ago.
It is a 2009 Mitsubishi Lancer. 2.0 engine. There has never been a check light come on.
Expert:  sprinkles08 replied 7 months ago.

Have you checked for fault codes?
Do you have the ability to monitor data?

Customer: replied 7 months ago.
No I don't have the ability to monitor any data.
Expert:  sprinkles08 replied 7 months ago.

Will idle speed fluctuate just with the engine running and the car sitting still?