Vehicle idles rough and dies when in idle

GRAN10EM

MEMBER
2000 MAZDA MPV
180 MILES

My MPV runs fine during the Summer (a bit of roughness on idle) but in cold snowy weather idles a lot rougher specially below 25-30 degrees and completely dies in idle when under 10-15 degrees but it maintains its RPM's when the gas is depressed. The engine service light is always on during Summer and Winter. I have replaced the Idle Air Control Valve but the issue persists. There is also a horrible gas smell around the car when the engine is on, we can also smell it inside when we switch the air to defrost or to defog the windshield. Please let me know if there are troubleshooting steps I should be following to narrow down the issue and let me know if you need more details. Thank you for your help!

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

More than likely this is a going to be a vacuum leak as it is causing the engine to run lean when it is cold.

Let's start by checking for a leak using this guide.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Also, if you are smelling fuel then it may be the opposite issue of it running rich when it is cold due to the regulator sticking.

So that means we need to check the fuel pressure and see if it is low/high when this is happening.

Here is a guide that will help with this as well.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Please run through these two things and let us know what you find. If both of these check out, then we are going to have to move onto a misfire so we will need to check the codes and go from there.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Thanks