Idle too fast? How adjust?

[ILO]

Hi,
My '95 starts and idles at 2300 rpm for a full minute when starting cold. It then drops quickly to 1200. If I shift to either reverse or drive before it gets to 1200 the transmission bangs as it goes into gear. Is 2300 normal? If not, how can I adjust only the cold idle?
Thanks,
Mike

 

[mzdalvr]

the computer controls the cold idle to warm the engine up to prevent damage. 2300 is normal and when the engine warms up it should drop. the idle range is located under your hood on the mazda sticker. our 3rd gens run 700-800 when warm.

 

[ILO]

Thanks for the quick reply. Since 2300 is normal, I take it that there's no way to reduce it? Or reducing it would cause a problem?
If that's so, is there any way to keep the transmission from making that sharp "bang" as it goes into gear before the rpm drops to 1200? Does that bang cause any damage to the transmission?
If we wait the full minute (which seems long while you're waiting) and shift at 1200 the transmission goes into gear nice and smooth.

Mike

 

[mzdalvr]

tru, you can adjust it but it would have to be adjusted by computer since the idle is controlled by the ECU. the sharp bang into gear is comparable to "neutral dropping" the trans - where u race the engine and drop it into gear. the bang usually isnt a good thing for a transmission because it puts stresses on the gears and such. usually the best thing is to wait not only because the engine is in "self warmup" mode, but its also good to make sure that the engine components are well lubricated before setting out - esp when its cold cause engine oil is usually at its most dense - so engine damage and wear will happen more quickly.

remote starters or just getting out a bit earlier to let the car warm up before you set out is your only options unfortuneatly.

 

[ILO]

Thanks for the thorough reply/info.

 

[jred321]

(don't know much about your car specifically but) what about the idle set screw? on other cars there's a screw that you can loosen or tighten on the throttle body to adjust the idle level. with the car running and fully warm you can tighten it until it almost stalls and then back it out a little from there. there are other reasons cars idle high but that is the simplest thing to fix.

 

[ILO]

Thanks Jred. I'll check into it.

 

[gybe]

Setting your idle speed by rotating the screw on your intake manifold is not all you must do to set the idle speed. You must also reset the ECU to do that.

Preparation:
1. check all hoses - air intake, fuel intake...
2. put the gearbox in neutral
3. turn off any AUX device, including A/C, radio, heating/blowing, rear window heating ... EVERYTHING! If you have power steering, align the wheels straight forward
4. do not warm the engine to the state when radiator fan goes on
5. check the ignition system - it must be 100 % flawless

Now here's the procedure:
1. start the engine and let it idle
2. under the hood you'll find a box saying 'DIAGNOSIS' - open it and connect GND and TEN terminals with a jumper wire (do not plug the wire anywhere on the pin but in the tinniest, most narrow part of the pin!!)
3. adjust the idle speed screw
4. remove jumper wire
5. turn off the engine

That should be it. Good luck!

 

[ILO]

Hey, thanks very much for that detailed info. That's what makes these forums so useful.

 

[Sudz]

My brother had a 91 Mazda Pickup. The idle is high to heat up the engine. It was carburated (not EFI) It would rev to about 2800 RPM if he let it while it was cold. Its a "semi automatic" choke. Try tapping the accelerator once (quickly, to about 3000 RPM or so) and see if it falls after that.

I'm certian that your car is Definately EFI... so this is probably all in vain... But he went through a lot of time at the mazda dealer to figure this out, then the dealer talked to someone from mazda in japan let him know the case.