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2000 Mazda Protege: air intake system problems

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Feb 5, 2013, 2:33 PM

Post #1 of 4 (8690 views)
2000 Mazda Protege: air intake system problems Sign In


Here my specs:
Protege LX
150K+ miles

When I went for an oil change, the mechanic said my vacuum hose was cracked and needed to be replaced. I didn't ask him to replace, and instead I checked it myself. I saw that air intake hose was cracked and almost splitting. I'm not sure what the vacuum hose is. I decided to tape the air intake hose temporarily while I order a new part. I saw some other things. They seem like problems to me, but I was surprised the mechanic didn't point them out. Here are some pictures.

Firstly, here's the whole engine:

Here's part "A" expanded. It seems that the areas I've boxed should be connected. I assume what I'm holding is the vacuum hose. Is this correct?

and for "B" it seemed there shouldn't be a gap between where I have the box. The compartment at the top is for the air filter.

I'm not a car expert, but I assume these are problems, correct?


My engine stopped while my car was idling yesterday, and that's the first time that's happened to me (this can be another topic). Other than that, no problems.

(This post was edited by autojunky on Feb 5, 2013, 3:01 PM)

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nickwarner profile image

Feb 5, 2013, 5:35 PM

Post #2 of 4 (8657 views)
Re: 2000 Mazda Protege: air intake system problems Sign In

You are right about having a problem. That piece you taped up is your air inlet ducting. If it isn't sealed your engine can draw air through it instead of through the air filter, which would allow dirt and dust to be ingested by the engine and cause it to wear out way faster than it should.

That hose coming from your valve cover to the air ducting in picture A is for your PCV system, and it also needs to be hooked up. I'd guess the missing section is because the hose deteriorated. A new one won't be expensive and you should fix it immediately along with the intake ducting.

Your airbox connection in picture B should be slid together as you have correctly pointed out. This isn't all that critical though, as all air going through that hole must pass through the air filter prior to getting to the engine.

Your stalling is likely dues to the issues in picture A. Your car has a mass airflow sensor in the ducting and the engine uses data from it to determine how much air is getting into the engine. If makes decisions on how much fuel to add based on that along with several other sensors. But with the PCV hose unhooked and the the air ducting damaged the engine is pulling in extra air that the MAF didn't read, and the ecm is getting confused when it sees the different than expected readings from the O2 sensors based on the fuel it added when it looked at the MAF reading. That extra oxygen was seen by the 02 sensor, which told the computer you were running lean and the computer added more fuel to make up for that. You need to get that fixed fast. I wouldn't drive it around while it can suck in dirty air directly into the engine. On the upside, fixing what is wrong with this can be done by a novice like yourself with simple hand tools you would commonly have around your home. A return trip to a shop would be unnecessary and the parts are inexpensive.

Get that taken care of, drive it around for a day or two and let me know how its running for you.


Feb 5, 2013, 7:20 PM

Post #3 of 4 (8649 views)
Re: 2000 Mazda Protege: air intake system problems Sign In

Thanks for detailed reply, Nick. I have noticed that my fuel economy has gone down.

When I replaced my air filter and taped the ducting, my engine check light went away. That light came on seven years ago, and my mechanic said it was for the EGR valve, which he said opened and closed too early. He said I needed a new valve, but he said the car doesn't need the part, and so we left it as it is. I always managed to somehow get the light turned off for inspections. One time I took my car in to get the problem fixed to another mechanic, and he said I didn't need a new valve, but just needed to clean it. He charged a bundle, but the light came back two weeks later. That was years ago, and when I went for an oil change recently, the mechanic said my light is on because of the air intake hose. I didn't think much of it because he didn't know the whole story, so I was surprised when the light went off today.

Anyway, I can find the air intake hose on RockAuto, what is hose coming from the valve cover called? I can't find another hose in the "Fuel/Air" section or any other appropriate hose. Is there a name for it?


Feb 6, 2013, 12:50 PM

Post #4 of 4 (8631 views)
Re: 2000 Mazda Protege: air intake system problems Sign In

I saw this video for installing a new intake hose: link deleted ...... not allowed and it says the hose is called a "breather hose." I couldn't find anything online, so I went to Pep Boys. They cut a fuel line hose for me, and it fits just fine:

I also bought some clamps. Got everything for $6.50. I later realized the old clamp I already had on the PCV would have worked as well. Boy, buying those clamps is paining me right now.

I'll go ahead and order the air intake hose. Thanks for all the help.

(This post was edited by autojunky on Feb 6, 2013, 2:31 PM)

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