Revs not dropping fully

[Gavinsmithartist]

Hi
I'm having contiuing issues with the revs not dropping to propoer tick over.  It sticks at about 1000 rpm, and sometimes higher. If I'm in traffic running in with revs about 2k, it can also stick there. If I jab the trottle it will returtn fully. It appears to be worse when the revs are dropping slowly. It dosn't appear to be kinked cable or peddle sticking as I can replicate it by hand on the throttle body.

I've had the butterfly out several times and cleaned. I dont want to use emery on  butterfly in case I take too much off (?).

It's a right bitch to drive in traffic.
All advice/ideas welcome.

[SM25T]

Is the body holding the butterfly plastic ? Air filter retaining clamp over tightened ... deforming the body ?

[Gavinsmithartist]

Thanks SM25T
It appears to be sticking in body, even without the air filter it sticks. Am I been over cautious with rubbing/cleaning the butterfly?

[SM25T]

Have you tried a spot of lubricant on the spindle ?

[DaveMorris]

I asssume you can disconnect the throttle cable from this butterfly - just to check that you've not got sticktion in the cable run. Dave

[CharlesElliott]

If you have a plastic throttle body, getting an aluminium one might be the best solution. You can get them on eBay for not much.

[SM25T]

You say you can replicate it by hand .... but as above ... disconnect cable. Favourite is a sticking pivot on throttle pedal. Lubricate that. But do disconnect cable and check three items separately .... pedal movement, cable inner and throttle body. Then you'll find the culprit. I bet it is the pedal pivot.

[Roadsport06]

It does sound like a sticking throttle cable, a thread broken off not always giving a clean return, but pivot likely too. If this turns out to be the case of the cable it is likely to get worse and snap. This happened on the last Aberdovey chip shop run. At Halt cafe it was holding by just 3 threads. I carry a spare though so was up and running in 5 minutes.

As said, a deformed plastic plenum could be an explanation (if yours is plastic). If you don't have a spare cable then make one. There was a thread last year about making your own for a few £.

[Myles]

With regard to the sticking throttle cable, this can be a bunch of laughs to catch if you do your testing with the bonnet off, find the problem is 'resolved' and then go for a drive.

I've had problems in the past where the cable works fine - except when it is gently bent out of natural shape when the bonnet is put back on. If you find this affects you, try zip-tying the cable as little as possible out of the way. You may need to do this in more than one place to achieve a smooth cable action. If nothing else, it should provide a level playing field (bonnet on or off) for further debugging...

...and help stop your cable/bonnet eating into each other over time!

[tbird]

I am sure you have probably done this but just in case, I had exactly that on my CSR and and after a lot of faffing around it turned out to be the screw holding butterfly to spindle was loose, once tightened fault was still there. eventualy worked out that with the butterfly  closed so you could tighten screw it sat slightly low in the housing causing it to stick. I ended up fitting screw but left loose, slipped tip of finest feeler guage  under butterfly then tightening screw, this gave just enough clearance top and bottom and all was tickety boo afterwards.

Tim

[tbird]

Any joy ?