Fast tickover

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Fast tickover

Post by jas_racing on Sun May 25, 2014 7:38 am

My Uno currently has a minimum tickover speed of 1800 rpm...checked all the obvious things (throttle linkage, ICV, etc) to no avail and will try swapping over components tomorrow weather permitting but thought I'd see if anyone has any tips or ideas on the matter?
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Re: Fast tickover

Post by Slim on Sun May 25, 2014 10:00 am

Sticky butterfly slightly open?
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Re: Fast tickover

Post by jas_racing on Sun May 25, 2014 10:37 am

Slim wrote:Sticky butterfly slightly open?

Checked that, it moves freely and even when fully closed the engine is still running at 1800rpm so I'm wondering if there's an air leak downstream of the butterfly?!
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Re: Fast tickover

Post by Slim on Sun May 25, 2014 10:48 am

I've never had anything similar to this happen to me so I can only speculate. Did it come about all of a sudden?
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Re: Fast tickover

Post by jas_racing on Sun May 25, 2014 8:27 pm

Slim wrote:I've never had anything similar to this happen to me so I can only speculate. Did it come about all of a sudden?
First time I fired up the engine a couple of weekends ago it initially ran fast but then settled to about 1000rpm once it was up to running temperature. Firing up yesterday however it stayed at 2000rpm even when warm.
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Re: Fast tickover

Post by Slim on Sun May 25, 2014 9:06 pm

What have you checked? Is the throttle position switch set up and tight?
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Re: Fast tickover

Post by jas_racing on Sun May 25, 2014 9:25 pm

So far I have:

- set the butterfly closed position according to spec (0.05 - 0.10mm gap at the bottom)
- checked the mechanism works freely and closes fully (it does)
- set the TPS correctly (i.e. so there's a 'click' just as the throttle starts to open)
- screwed the main idle adjustment screw all the way in (screwing it out makes tickover even faster)

Then with the engine running I've squeezed the ICV and DV pipes closed to rule them out (made no difference)
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Re: Fast tickover

Post by Slim on Sun May 25, 2014 9:33 pm

Timing?
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Re: Fast tickover

Post by gtirx2 on Mon May 26, 2014 12:30 am

Mine did this and it was the throttle butterfly that was worn out,it all measure up correctly but was worn just enough to cause a problem.

You could also try adjusting the screw on the afm as this affects idle and off boost cruising fuelling but if you idle is that high I dout its this causing the problem and messing with this will affect your afr's.

To higher fuel pressure can also cause it if you have an adjustable fpr fitted.

Try removing the top 90 degree boost pipe going to the plenum turn it 180 degrees and blow down it and see how much resistance can be felt when blowing against the throttle butterfly when its shut,i know there was a marked improvement when I changed mine as before very little resistance could be felt.

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Re: Fast tickover

Post by jas_racing on Wed May 28, 2014 7:55 am

Problem solved - a combination of fitting a brand new TPS, turning the circular brass plate in the butterfly assembly over (I assume I fitted it the wrong way around when reassembling) and slackening the throttle cable this evening has her ticking over at 900rpm Smile

Thanks for the hel & suggestions guys  rockon 
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Re: Fast tickover

Post by jas_racing on Wed May 28, 2014 7:55 am

jas_racing wrote:Problem solved - a combination of fitting a brand new TPS, turning the circular brass plate in the butterfly assembly over (I assume I fitted it the wrong way around when reassembling) and slackening the throttle cable this evening has her ticking over at 900rpm Smile

Thanks for the help & suggestions guys  rockon 
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Re: Fast tickover

Post by Slim on Wed May 28, 2014 8:30 am

Excelent news!  Very Happy 
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