I'm new to the Mazda scene and don't really understand why my 97 Protege is doing this.. Say I was driving and was coming to a complete stop, and i throw my car in neutral why I idle to wait for the light change. When the Idle is at 700-750 I guess that is normal, but my car will sometimes go from 700- to like 400 and back up to 750 and maybe back down to 400.

There is no engine code being thrown and for some odd reason it leaks a bit of oil, but I always make sure she is topped off to the full line, so I don't think it would be that. Car seems to work perfectly fine other then that. Any idea what could cause this Mazda Enthusiates? haha

Thanks.

 

inspect intake air hose CAREFULLY for cracks . idling engine fine, but crack open when the engine torques .No CEL's ???? ......hmmmmm.

 

...??

No, there is no CEL's at all. The intake is a little old, it's just a stock intake, the intake pipe itself might be a bit dirty and the filter not too worn. Any other hose's I should be looking at?

 

the reason why there is no code is because the leak is behind the mass flow air sensor, for all the car know's there is no leak because it cannot read a change in the air flow so its not going to be in the intake and if it is it will be between the motor (throttle body) and the mass flow air sensor. my best advice is to check every vaccum hose in that car, somewhere there is ithier a crack, or an in-dent that when the car vaccum's when you let off the gas pedal is squezzing a vaccum hose, to start off check the hose that run's to the pvc valve, not the valve itself it should be fine but the hose it should run from the back of the intake manifold to the pcv valve going into the exhaust manifold, if thats not it check all the vaccum hoses somewhere there is a leak i had the same problem with my focus it turned out to be the pcv hose.

 

will do! I changed a pvc valve before on my civic and it was a way bigger job then for the protege, and its not a very expensive part at all so I may as well change that. Ill check that hose and all the vac hose's tomorrow after work.

I just wanna fix the problem before anything worse might happen. thanks!

 

so I wounder if this problem is related to my current problems with my alternator? would it affect the rpm rev level if a belt wasn't tight enough or something? I never found any vac hose leaks, but the problem is still doing it when the car idles..

 

I'm no expert but have seen a lot in my 00 protege.

Things I'd check.

1. Vacuum leaks (but it sounds like you covered that). When my intake hose cracked, I'd get funny codes like bank 1 too lean or Catalytic converter below threshold.
2. Does your battery go completely dead because of your alternator issue? When ever I disconnect my battery, the car goes through a process to relearn the correct idle speed. It normally fluctuates between 400-700 2-3 times once the engine warms up and then doesn't occur any more.
3. Clean the Idle air control piston. I do this by starting the engine and spray carb cleaner directly into the IAC port. You'll probably have to keep the throttle cracked as you spray. Clean the throttle plate while you're at it (Engine Off). I use an old tooth brush and carb spray. Have a helper hold the throttle plate open so you can scrub the mating surface between the plate and throttle body.
4. Clean the intake air temp sensor. Mine is located in the MAF. Not sure where it is in the 97. When mine was dirty, the engine would cut out intermittently normally under load and heavy throttle. Took several months of this before it finally threw a code. Clean the MAF while you're at it. I use brake parts cleaner but allow it to dry thoroughly before reconnecting. Perferrable use light compressed air to dry. Do not attempt to touch the electric coil inside.
5. Spark plugs and boots/wires. One of my cylinders leaked oil into the plug cavity and created a intermittent miss but normally under load and heavy throttle.

Don't know if this will solve your problem but won't hurt and you'll spend <$10 on 1-4. Good luck.

 

thanks alot for the reply motorhead. ill check a few things out tomorrow after work and see if that will fix my problem