mazda123x5

Hi, I have been working on learning how to set my idle
speed and I think that I have got it running o.k.
But still every once and a while mostly after the
car is warmed up or after a steady cruise it
will hang at 1300 rpm then at the next stop
its back to 900 its seems better i.e. doing it
less frequently. But I wonder what part could but
doing this it seems there is something sticking or a vent valve thats starting to go. I was thinking its maybe
acv I am going to ckeck it when I get some more time.
So have any of you that drive a gsl-se had a similar
problem and what was causing it?

Thanks

LongDuck

At 26 posts, you really should take a few minutes to run a search against "SE" and "idle". This will turn up a lot more information than just what I can relate here...

What I've found on my SE is that the idle speed tends to change from time to time when the BACV (Bypass Air Control Valve) is getting dirty. This is the barbell shaped thing hanging off of the driver's side of your RE-EGI Dynamic Chamber. What happens is that when the BACV gets dirty, it will tend to stick when it should open or close a little bit more. This results in a slightly higher or slightly lower idle speed when the engine returns to idle (as in your example, from light to light). While it only every moves about 100-200rpm, IME, I've found that if you're really picky, remove and clean out the BACV with carb cleaner, and it should solve the problem for awhile.

If you find that the A/C has a tendency to bog the engine down when you turn it on, there is an adjustment on the BACV underneath a black, plastic disk on the left side. Remove the plastic cover, and there's a screw in there. Back the screw out to increase bypass airflow, run it in to decrease bypass airflow, and this is what adjusts how high the idle compensation is set when the car needs more throttle to compensate for A/C or electrical draw. Reseal the cover and you're set.

There are a lot of things that go into a smooth and steady idle on an SE, and the BACV is only about 20-30% of the available causes. If this doesn't fix the problem, you'll probably want to look into the vacuum solenoids that control the BACV, and/or the TB and hard idle settings and idle mixture adjustment.

Good luck, and HTH,

mazda123x5

Thanks LongDuck I have cleaned the bac valve and done lots of reading and searchs on idle problems.
I recently downloaded the factory manuals. Its just
that this is all new to me. I will look at the bac again
clean and lube it and and check the vacuum solenoids.
I am trying to learn how to fix things myself. The forums
have been a great help I have fixed many things already that I could have never fixed without all
the good advise I have found here. thanks for your help.