How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Matt Your Own Question
Matt
Matt, Engineer
Category: Kia
Satisfied Customers: 20592
Experience:  Mechanical Engineer BEng Hons22 years experience in car engine industry, 10 years in formula 1
12772297
Type Your Kia Question Here...
Matt is online now
A new question is answered every 9 seconds

We just bought a 2013 soul....eco package. When at a traffic

Customer Question

We just bought a 2013 soul....eco package. When at a traffic light, if it does not turn off, the idle seems rough...like the engine vibrates. Car runs super fine no hesitations at any other time. is it because the idle is set differently so the engine can turn off/on when stopped?
JA: Is the rough idle intermittent or consistent?
Customer: consistent at traffic lights
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: no...we really just bought the car. just put a tank of premium gas in yesterday.
JA: Anything else you think the mechanic should know?
Customer: the idle is only rough when the engine doesn't shut off at traffic lights. smooth the rest of the time. starts back up if it's in ISG mode with no problems. doesn't lose power at any time, no hesitation going up hils.
Submitted: 3 months ago.
Category: Kia
Expert:  Matt replied 3 months ago.

Hello

This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.

As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running.

Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts.

The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engine

Might also be worth checking the wiring and connector to the airflow meter for any signs of corrosion or damage. you can do a quick fault find if you unplug the meter and run the engine without it.

if the engine condition is the same then chances are the meter or the connection to it is faulty

It’s also worth cleaning the MAF sensor wires, as they can get coated with dirt over time which then offsets the reading

Use some contact cleaner or brake cleaner to spray onto the wires to remove the dirt – on no account touch the wires with anything as they are very fragile

Expert:  Matt replied 3 months ago.

Hi

do you still need help?

Bear in mind that the site takes a deposit from you at the beginning and this is held by the site until you rate my answer at which point the cash is split between the site and the expert. I am only paid for my work on this question if you rate my answer, using the star system at the top of the screen. Please do not forget! Thank you