Symphony tickover

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Symphony tickover

Post by boxerman on Thu Jun 01, 2017 7:22 pm

I arrived home a couple of nights ago and the tickover was very high. I got out of the van to open the gates and the tickover dropped to normal-ish, then it increased and then it dropped etc. etc... It was late so I left it until the morning.

In the morning it was just the same - up and down. I decided that it might be the stepper motor so ordered one off eBay.
I have to say that I was impressed with the service, I ordered it in the afternoon and it arrived the following day, all for the princely sum of £8:50 inc p&p. It was from This Seller. and it even came with the two torx fixing screws.

Undid the old one [genuine Magneti Marelli] and it fell in pieces as the second screw came out, which I thought was a good sign.
Fitted the new one and after a couple of ups and downs, it settled to a nice even tickover. Tried it again today before writing this and the job seems to be a good un!

Just thought I'd pass that on.

Frank
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Re: Symphony tickover

Post by Bartfarst on Sun Jun 04, 2017 9:35 am

Sounds like a very good outcome Frank.

Does that stepper motor only control tickover revs? If so what is the logic behind it rather than a simple adjustable backstop?

Stuart
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Re: Symphony tickover

Post by boxerman on Sun Jun 04, 2017 1:08 pm

Hi Stuart
Bartfarst wrote:
Does that stepper motor only control tickover revs?
Yes, just the tickover. The motor converts rotational movement to linear movement of the cone on the end of the shaft.
This cone moves in or out of a tapered bypass orifice in the throttle body to control the amount of air going to the engine.
If so what is the logic behind it rather than a simple adjustable backstop?
The ecu can control the tickover speed dependant on engine and ambient conditions. A fixed throttle stop may be fine for one set of conditions but not for another. [Although, probably like you, I've never found it an issue]

As a practical example, before the up/down tickover started, I found that I was having to give it a little bit of throttle before it would start. Now when I start it, it will start without my foot on the pedal. In fact, when it starts, it sounds like I am giving it a whiff of throttle for a second or so, then it slows down to it's normal tickover speed.

Frank
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Re: Symphony tickover

Post by Bartfarst on Sun Jun 04, 2017 1:21 pm

Thanks Frank.

All makes sense!

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