RPM drops and dash lights come on

[felizcortez]

When shifting the car occasionally from park into drive, the RPM will drop and the lights on the dash will come on and the car feels like it has no power. It's a 2007 2.3L Mazda 6. Also sometimes this happens at stop signs and seems to be an issue more when the engine is cold. It has happened a few times in the last few days, any thoughts on what I could do to check this out to see what is going on. The check engine light is not on. The car has about 90k miles on it and I replaced the spark plugs at around 75k. Any help is greatly appreciated. Thanks.

[elemento_74]

I would start by checking for vacuum leaks

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[ctmazda]

^+1. Sounds like either a vacuum leak or maybe old ignition coils if not a vacuum leak since you said you changed your plugs already. Any flashing CEL's?


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[felizcortez]

I haven't seen any check engine light codes. I don't have a scan tool and the CEL is not on.

Anyway I can check to see if there are codes without a scan tool?

Also what is the best way to check for Vacuum leaks? Are there any hoses that I should pay particular attention to? Is there a schematic of the vacuum system so I know I don't miss anything?

Thanks again for the quick responses, this is very useful.

[elemento_74]

If the CEL never came up you shouldn't have any codes to read,and yes,you do need a scan tool to read any codes,autozone or advance auto parts can read the codes for free.
There are a couple of videos on YouTube on how to check for vacuum leaks

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[Final Impact]

Its V6 cousin gets some of the idle air through the PCV (positive crankcase ventilation) system. Engines that don't receive regularly schedule Oil changes can gum up this simple check valve and have idle variation issues. As best I tell the L3/2.3 is a little different but it is service item that should be changed at scheduled maintenance intervals.

I personally run Techron Fuel cleaner at least 3 x year to reduce the deposits on the injectors and rest of the intake track. It can't hurt and also keep in mind that winter temperature changes tend to create more condensation in fuel tanks and fuel cells. Some of these products will help keep the moisture in suspension in the fuel tank so it gets burned instead of resting at the tanks bottom to sicken your car with unburnable content.

Can someone else chim in on the 2.3 PCV? Is it connected between the TB and the cylinder heads intake track?

[xkreedx]

The PCV is connected under neath the intake manifold. You need to remove the intake manifold to access it which is ~two hours worth of work if you know how to use simple tools. There is a write up in the 2.3 how to sticky.

[Final Impact]

The AJ V6 3.0 is easy to follow but I don't have schematic of the L3.

This shows why the metering orifice diameter of the PCV is important and how sludge build up internal to that orifice can change the idle making the ECM have to perform corrections idle control air at the TB.

Fresh air is available at the air filter. When the throttle is closed at the TB, the engine is running and idling burning its own fumes from the crankcase.

Air in at air filter, into the Red hose on top. Is sucked into one valve cover and through the crankcase and out the other valve cover BEHIND the throttle plates and back into the intake (blue). Again - for all those who wish to blame the PCV valve for oil consumption, NOT ITS FAULT! An engine that is poorly maintained and has blow-by past the piston rings will burn and consume its own oil. If anything - that valve slows it down.

You can also see why the accordion hose fills with oil. The more blow by an engine has, the greater the odds are that it builds MORE pressure than the PCV system can allow into the intake track so littlerally builds up in the intake ahead of the TB.

Can someone find an illustration like this for the L3?