Tune Up

The alloy body that the valve fits into and is bolted to the plenum with 3 allen bolts should have a gasket to seal it against the back of the plenum, that is the gasket I was referring to, fibre washes can be bought from any spares shop, as can gasket paper, Regards Frank.

I never bothered with a new gasket, just use a smear of RTV on the thread and screw it back in.

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Originally Posted by It'sNotWorthComplaining!

I never bothered with a new gasket, just use a smear of RTV on the thread and screw it back in.

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What channel is RTV on :wasntme:.

If I go that way won't the stepper motor need to be reset - if so is it key on - key off - key on - key off, after waiting a few seconds between each on/off.

If you listen carefully, is that the stepper motor you can hear initalizing when you first turn the key on.

Regards
Rich

No the sound you hear is the fuel pump pressurising the rail.
The stepper opens fully as you turn off.
That is why the engine revs up as you start and then slows to the correct idle, maybe with a couple of bounces .
No resets are required.
Regards Philip A

Quote:

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Originally Posted by PhilipA

No the sound you hear is the fuel pump pressurising the rail.
The stepper opens fully as you turn off.
That is why the engine revs up as you start and then slows to the correct idle, maybe with a couple of bounces .
No resets are required.
Regards Philip A

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Thanks for that info,

Does the stepper look as though it has opened fully (see pic) or is it supposed to sit flush with the base.

If I wanted to clean the stepper in the extended position (closed) could I after removing it, just re-attach the plug and turn the key on, or is it not necessary to go that far to clean it.

Regards
Rich

This I learned from painful experience. After I broke one I pulled it apart to see how it worked.
Do NOT try to screw out or pull out the stepper cone from the base.
The stepper photo you show is fully retracted, and this is the correct "resting " position. ( when I said 'opened" maybe I should have said "retracted" as by retracting , it opens the flow of air past the cone and seat)
Inside the stepper there is a stepper motor (surprise) that turns according to Binary signals from the ECU. The motor armature turns and the cone has a rack /thread on the shaft which screws the rack in and out. The rack has a keyway to stop it turning with the motor so it goes in and out.
if you try to pull out the cone, it will break the keyway. You cannot wind it by applying a voltage either.

You can pull the plug while the engine is running, and this may expose some of the shaft, but really if the stepper is so slow that it cannot control idle within a few rev oscillations , then it is time for a new stepper. There are many on Ebay at reasonable prices as these were used in many Chevrolet models.
Regards Philip A

Quote:

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Originally Posted by PhilipA

This I learned from painful experience. After I broke one I pulled it apart to see how it worked.
Do NOT try to screw out or pull out the stepper cone from the base.
The stepper photo you show is fully retracted, and this is the correct "resting " position. ( when I said 'opened" maybe I should have said "retracted" as by retracting , it opens the flow of air past the cone and seat)
Inside the stepper there is a stepper motor (surprise) that turns according to Binary signals from the ECU. The motor armature turns and the cone has a rack /thread on the shaft which screws the rack in and out. The rack has a keyway to stop it turning with the motor so it goes in and out.
if you try to pull out the cone, it will break the keyway. You cannot wind it by applying a voltage either.

You can pull the plug while the engine is running, and this may expose some of the shaft, but really if the stepper is so slow that it cannot control idle within a few rev oscillations , then it is time for a new stepper. There are many on Ebay at reasonable prices as these were used in many Chevrolet models.
Regards Philip A

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Thanks mate,

No I won't play around with it any more as I am happy with it's performance, it's more that I am the inquisitive type and like to fiddle to the stage of getting into trouble, but I am now learning to ask questions before trouble strikes.

Pity I didn't learn to do it 40 odd years ago:mad:

Ps: I found some fibre washers in Bunnings tap section that done the job.

Regards
Rich