Mazda 3 2005 Rough Idle/Engine Light
 

I have a 2005 Mazda 3 I bought brand new. It has been a very reliable vehicle and I have had absolutely no mechanical issues, until now 50,000 miles later.

The problem 1st presented itself as a hesitation to start (normally fires right up) after filling up the gas tank on a cross-country road trip...This happened a few more times in subsequent filling station visits...the problem was short lived and the car seemed to run fine after the fact....

The 2nd symptom a week later was the check engine light, this has happened before as a result of my gas cap not being on properly, i learned my lesson the first time, so i figured it wasn't the case, i opened and replaced my gas cap just in case, a few miles later the CEL went off

3rd symptom, my car started idling rough at stop lights and the CEL came on again...

i just took it for a tune-up, oil change and transmission flush, started my car and the light was off...on the drive home it still idled rough and right as i was about to turn the engine off in my driveway the CEL came on again

my guess is give it some time to let the fuel injector cleaning fluid used by the mechanic work through the system, but i'm being optimistic

ANY IDEAS!?

john

You need to find out what the cel is. That will most probably tell you what is wrong.

is it common to be charged $98 to diagnose a CEL??

Yea, that's probably about right. They usually hit you for a $75 minimum.
On the other hand, you could probably buy a OBD reader for your car for the same or cheaper.

I know this sounds silly, but just take it to Autozone or Advance Auto Parts. They will hook up a code reader and pull the code.

That code will tell you what is causing the light to come on.

With that info, you can figure out what is causing the problem. There are too many variables at this point to accurately troubleshoot. DO NOT PAY GOOD MONEY TO HAVE SOMEBODY PULL A CODE FROM YOUR CAR. The parts stores do it for free b/c they figure you're going to need to replace a part or two.

Post back with the error code.

Your other option is to take it back to whatever shop just did this 'tuneup' and tell them what happened. They can tell you what the code is. They had to reset it before giving you the car back. You just paid them good money. They should rectify the situation free of charge, or you should never take your car there again.

If this is not a dealer, then they may have changed your plugs and put some non-iridium plugs in. This will cause your car to stumble like you are describing. It will trigger a CEL. Usually, the error code with this will be "random misfire, multiple cylinders".

No code...
 

I am having the same idling problem, as well as an accelerating engine right at about 1000 rpms. Had car worked on today and they said there was no code. Any ideas when there is no code issue?

Hey Heman,

Thanks for the website! The OBD2 sounds awesome. Wish I had had it earlier. My mechanic used the guide and followed it up all the way to replacing the throttle body. They cleaned it manually, very thoroughly, but it was still doing it. We considered having the computer flashed, but tighy now the Mazda is doing it only slightly, so I'm holding out. I can still replace the throttle body, but am just waiting to see if it gets worse again.

http://www.scangauge.com/ Get one! No......it's not spam!

i recently had issued like you with rough idle and a hard start up after a long trip...the answer is the purge valve and clean your air throttle...and you can install the purge valve yourself just open the hood hope this helps

I know this sounds silly, but just take it to Auto zone or Advance Auto Parts. They will hook up a code reader and pull the code.That code will tell you what is causing the light to come on.

I guess you work there the solution to the problem of the car is changing the purge valve and clean the air throttle why go somewhere and pay when the solution to your problem is right in front of you.....i have a friend that works at a Mazda dealership and he told me they sell many purge valves per week.

Is there such thing as an overall kit for mazda 3's

You could have overfilled the tank and gotten gas into the evaporative emission system. I'm not sure if you can pull it off and clean it / dry it out or if it'll fix itself over time.

I got the same problem
 

My wife's car is a 2005 Mazda 3i. It has been idling rough, sometimes it won't start then ten minutes later it's like nothing happened. We noticed some of that stuff with the gas cap too. the check engine light for ours is code P0661 Intake Manifold. we have 48,000 on ours. I have no idea what to do our warrany ran out last year. the guy said 120 an hour to daignose the code we also had the AT code come one P0715 either way it's gonna be costly I haven't been able to find much info on it

P0661 is the "variable intake air solenoid valve" circuit low (P0662 is stuck high). The solenoid is attached to a relay to battery (like ignition) and the control module in the car pulls the other side of the solenoid to ground. The control module is seeing the solenoid at ground all the time, which means that there is a broken wire / bad connection / burned out coil in the solenoid.

I'd guess corrosion on the connector causing an open circuit due to its location. If you pull the plastic cover off the top of the engine, there are two solenoids attached to vacuum lines on the left of the engine, right up top, the one at the left is the variable intake solenoid, the one on the right is the variable tumble solenoid valve (P2009 / P2010). Inspect the connector for corrosion, and see if you can figure it out.


P0715 "input/turbine speed sensor circuit malfunction" Gets set if there is no input from the sensor for more than 0.7Sec and the vehicle is in drive, and you're traveling more than 25MPH.
I can't see from the pictures where the sensor is, but you have to take the battery box out to get to it... so probably right on top of the transmission. I've got a manual trans so can't help you there.
Again i'd assume corrosion, the sensor should pulse at ~350hZ when the engine is at idle in park. The resistance should be 250-600 ohms - good luck troubleshooting.


If anyone wonders - this is why the set of manuals is handy for the car - finishlineperformance.com $140 for the manual and $80 for the schematics... well worth it, especially if you spend under $100 on a code reader like was mentioned above. YOU WILL SAVE $ FROM THE SHOP.
Good luck getting your ride running well again.