Check Engine Light, Low Idle etc
 

Hi there,

Hoping someone can give me an idea of what I may be dealing with on my 08 Mazda 3, 2.0L.

Check engine light came on today, and I noticed at an idle the RPM seems to be much lower than normal. Currently around 500-700, has always been about 700-1000 rpm. Additionally I have noticed a slight shudder when starting the ignition. Over the last several weeks there has been a drop in fuel performance.

Has anyone had similar issues, or know what may be the cause?

Thanks!

Hi Cori, Based on your description, I have several suggestions. It sounds to me like an air/ fuel mixture problem. Either your EGR valve is stuck open, causing your mixture to be diluted and therefore noticible power loss during idle. It could also be a faulty MAF sensor problem, Failure to sense the amount of air coming in and therefore not able to put in the required fuel for best combustion. oxygen sensor could also be the problem, If your oxygen sensor is faulty and tells the pcm you are running rich for some reason, your car will lean out the mixture causing power loss or low idle. Spark plug could be faulty too, maybe causing one of the cylinder to not fire. I don't know what kind of equipment you have, if you have a DVOM you could check for the circuits to make sure they are all working within spec, If not I would start out by checking the spark plugs to make sure you have good spark in all the cylinders. well the easiest way is actually to find out what code you have thats related to the engine light.
Blindly replacing parts may end up costing you more at the end.

do you get a check engine code? it could be a vacuum leak, faulty pcv valve (easy to check, cheap to replace) up to a dirty egr valve like dasesany says. let us know uf you have a code

Idle air control / throttle body could be dirty. Some simple carbon stuck in there could plug something up & cause problems.