Hello all.
I hope someone can help. In the picture below you will see two adjustments on the throttle body. The larger of the two is for setting the idle; I found that in the Chilton manual. The second, near the top of the pic is an adjustment, this one seems to control some kind of vacuum flow. I was looking into the engine suddenly running bad, started tweaking on stuff before I found a huge crack in the air supply boot down-stream from the filter. I need to know about where to set the two adjustments, and what a reasonable idle would be...manual does not say.

http://s96.photobucket.com/user/crai...zda%20626%20LX

Many thanks,

Christopher

Check out the forums over at mazda626.net. Not much activity there but the few regulars are quite knowledgeable. I myself own a '90 626LX. I love it!

Thanks.

Well, dont know if you found what you are looking for yet or not but basically saying that neither of those two screw should be adjusted on for a properly running engine. The screw next to the throttle linkage is for bas idle adjustment. The bigger screw goinf into the throttle body is an air bleed adjusment and it controls air flow bypass passed the idle air control assy. If you feel you need to make a minor idle adjustment, you might try adjusting the bigger screw a little bit. Loosening the screw should allow more air bypass and increase the idle speed. You dont really want to mess with the little screw too much because it will start opening the throttle plate and increase the TP voltage.

Your running problem should be fixed first, that air intake tube is probably the problem and they were notorius for cracking and can cause all kinds of running problems from idle concerns, to bucking, jerking and loss of power on accel.

TP voltage? Is that throttle plate?

TP = throttle position but the throttle plate is directly related to the throttle position. The TP sensor is mounted on the side of the throttle body and it is splined to the same throttle shaft that the throttle plate is mounted to.

The boot is now replaced. The small screw with the lock-nut is bottomed out and tight. I have the larger screw adjusted to where when you rev the engine momentarily, it does not bog down (recovers to a smooth idle again). I think this should work for now, but I would like to get it adjusted properly. Thanks.

post a pic! Here's my little 626:

Im not quite sure which screw you were messing with to adjust idle, but from the sound of you description and pic the small screw with a jamb nut doesnt sound like its for idle. In your pic just to the right of where the throttle linkage goes into the throttle body you should see a flat head screw down in a circular recess, thats for idle speed adjustment. I really dont know what that other screw is with the jamb nut, but it looks like it helps control vacuum/flow to one of those vacuum lines.

There should be a single wire green connector over by the drivers side strut tower or along the inner fender area. Use a jumper wire and ground that wire out to the body or negative batt post. On a warm engine the idle speed should be around 750 RPM. Use that flat blade screw to adjust idle up/down to spec.

I believe the one with the jamb nut is for the butterfly adjustment. The problem you have could be that something is warped somewhere? Mazdas' like to warp things. whether throttle bodies, air intake flanges, you may have just bypassed the problem and not fixed it.
Where in NW MO are you? I may know someone that can help.

Just outside Rock Port. I'm getting 28 MPG and engine runs well, so I might just leave it alone

Mine gets about 26. Fantastic for a 23 year old car. It complements the weekender XJ well

right on