I've got a 2001 Millenia S with 49,000 miles on it. Recently I have noticed that when I'm idleing the car in my garage, at a stop sign or anywhere, the engine will drop below the normal idle RPM and it feels like the engine is about to stall. It does this about every 30 seconds or so and then the idle RPM goes back up, but still a little below the normal RPM for idle. The car runs fine and I don't think I've lost any power when I'm driving it. Any ideas what is going on?

Thx forthe help

 

babarf1bar

I experienced the same problem a few years back that ended up being a cat problem.
In this particular case, the car would idle very hard from time to time and then almost shut off. The CEL would stay on and not come off.
The Mazda dealership actually had to replace all 4 O2 sensors AND the 2 cats to figure out what the problem was, instead of replace the cats first. They had to follow procedures to troubleshoot the problem

 

Thx Vanesco. Do you, did youhave a Millenia S? What is a cat and what is the CEL(Check Engine Light)? My CEL comes on sometimes and I remove/install the interior fuse and the light goes out.

Thanks again for the info. I'm taking it in Tues AM to see what the dealer says is the problem. I'll post what they do to fix the issue.

 

replace both cats and all 4 oxygen sensors to fix an IDLING problem? i dont think so. so, i guess that when you have a running problem, they will replace the motor? what does the cats have to do with idling? i hope this was done under warranty, cause if this was customer pay, you got hosed. BIG time.

a small air leak can cause the idle to hunt. most suspect would be 1 or more of the plastic "tee's" that they use, sometimes, they just crack, and will leak intermittently. this will make the idle valve go nuts(idle valve is controlled by the pcm) trying to keep up. sometimes it can, sometimes it cant. it seems like every 's' has the broke tee problem, just a matter of time.

the reason your ce lite goes out after you do the fuse deal, is because you have cut power to the pcm, and it then erases the memory. you need to find out WHY the ce lite is lit, then go ahead and erase it. the car is trying to tell you something. also, changing the tee(s) is very labor intensive, it will cost you several hundred bucks at the dealer. the first time, it cost me 564. the next time i did it myself. took less than 3 hours, and i had the parts in stock.

 

Thx keninn, you gave some good info. What and where are the "tees" you are referring to? I dig the car and the Miller cycle engine, but don't know much about it(engine). Where the hell are the damn spark plugs! I hear they are on the bottom of the engine - great design......

thx again

 

The problem was fixed on 5/29/07. The T connectors (3 of them) for hoses were melted under the manifold. Dealer put new ones on and car drives great. Cost me $450 and $425 of that was labor.

 

Keninn, you said that you replaced the "T's" yourself. How hard are they to get too? And where did you get the replacement "Ts" from? My moms Millenia is having the same problem. It's worth a couple hours of my time replacing themif it willfix it for her.
Thanks for the help!

 

iirc, there are 3 different tees. i just ordered an assortment, and plus i have several left over from removal of the vacuum system on the mitsubishis i used to have. the mitsu tees are a lot more hardy than the mazda ones.
to get at them, you remove the plastic cover that says miller cycle, then you remove the intake tubes that come off the compressor. i dont remember if i removed the rear intercooler, but if you do, then to get at all the bolts/nuts for the rear intercooler, you have to pull the battery. i think i did pull it. both intercoolers and all the intake going to them. i left the abv connected, too. once you get it off, you can see all of the tees, and the ones that are the biggest problem are the ones right under the part of the intake that comes off the compressor. one of the tees is actually accessible without removing the intake, but you will not see it until you do. i would advise you to have a lot of the vacuum line, too. next time i go in there, i will change out all the line, too.