Mazda Rotary Club

General => General Technical => Topic started by: Matts-gen2 on October 04, 2007, 11:53:40 AM

Title: Fast idle nut?
Post by: Matts-gen2 on October 04, 2007, 11:53:40 AM
Is there an easy way to know the fast idle is adjusted correctly, was fiddled with when throttle was getting stuck, being mistakened for something else.

On a gen 2.
Title: Fast idle nut?
Post by: Brett on October 04, 2007, 12:06:52 PM
Are you referring to the adjustment screw on top of the UIM?
Title: Fast idle nut?
Post by: Matts-gen2 on October 04, 2007, 12:12:57 PM
no not the idle screw.

on the front, theres the two barrels, the lower one has a nut on it.

that nut has been turned and just wanna know if theres a way of telling where it needs to be adjusted to.
Title: Fast idle nut?
Post by: Matts-gen2 on October 04, 2007, 12:15:02 PM
i have read this is the fast idle nut.
Title: Fast idle nut?
Post by: Brett on October 04, 2007, 12:53:30 PM
I know where you mean - the easiest way to check is to see what the idle sits at when cold - it should be 1500, and gradually drop to 750 as the wax pellet warms. :yes
Title: Fast idle nut?
Post by: Matts-gen2 on October 04, 2007, 12:58:02 PM
i see, so how does the UIM idle adjustment control things?

is the UIM idle adjustment minor adjustments, and the fast idle bigger adjustment?

When trying to set idle what should be adjusted?
Title: Fast idle nut?
Post by: Brett on October 04, 2007, 01:18:43 PM
The main screw on top of the UIM sets the base idle speed (when the engine is warm) assuming your nominal warm idle speed is around 750rpm then theres no need to touch it.  
 If your cold idle (fast idle) is consistently above/below 1500rpm (bearing in mind this will drop as the engine warms) then adjust the fast idle to suit. (It\'s been about 3 years since I last had an EGi - but I think i\'m right)

:wave
Title: Fast idle nut?
Post by: Matts-gen2 on October 04, 2007, 01:18:58 PM
What i mean is should i

1. Turn the idle screw on the UIM fully closed then back off 1 turn.
2. Adjust the fast idle to 1500 rpm
3  minor adjustments on UIM idle.
Title: Fast idle nut?
Post by: Matts-gen2 on October 04, 2007, 01:21:24 PM
Okay, one last thing can the fast idle be adjust while running, clockwise is to lower RPM?
Title: Fast idle nut?
Post by: Brett on October 04, 2007, 01:44:21 PM
I don\'t see why not, just be careful not loose any fingers in spinning things!
Title: Fast idle nut?
Post by: Matts-gen2 on October 08, 2007, 10:15:52 AM
After reading up on fast idle, i found that the nut which i thought adjusted fast idle actually adjusts the bottom butterfly in the  UIM.  

The actual adjuster is on the flat headed screw which goes through the spring on the front, the part which the oil metering rod is attached.

On closer inspection, it seems there is a small amount of play in this part.

The part that you push to rev the engine, doesnt return fully, i.e. if you push it up lightly (opposite way to reving it ) it moves approx 3mm.

Is theis likely to be play in the bottom barrel, or a dodgy TPS?

Matt

:Hammer