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Help and Advice please

I have a 1979 911 SC Targa

It runs like a dream on motorways but around town is a real issue as it hunts and jerks at slow speed

Any thoughts as to reasons or remedies very much welcome

Tony

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Hi Tony,

does it start and idle ok? First thing I’d check would be HT leads, dizzy cap and rotor.  If it runs fine on motorway but struggles at slow speed under load you probably wouldn’t notice a slight misfire on one cylinder but it tends to become more apparent at slow speeds.not sure about the hunting though if it idles ok. 

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I had some low down misfire type issues - have a read: 

I would suggest you check spark first.  Timing, rotor arm, leads, plugs and cap. Then move onto fuel; mixture, pressures etc. 

I think one of the problems I had was because my new rotor arm was dodgy. 

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Welcome to CIS. It could be many things and as above you will need to check them all. Other things to check are vacuum leaks and electrical connections to the many ancillaries associated with the CIS. There can't be many owners who can, hand on heart, say they don't have some degree of hunting and kangarooing. Even with expert tuning mine was never enjoyable to drive around town or in traffic.

Welcome, by the way.

Edited by Phill

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2 hours ago, Phill said:

 There can't be many owners who can, hand on heart, say they don't have some degree of hunting and kangarooing.

I must be one of the few then Phill, hand on heart, no hunting and/or kangarooing.

As said above, trouble shooting needs to be systematic and thorough, with a certain amount of understanding of the system and reference to a decent manual.

Mark

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Hi Tony, after the basic ignition stuff there’s a load of good info on K-Jet CIS here.

 

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I had this issue with my ‘first edition’ 74 K-Jet. Fixed it with new injectors. No kangaroo issues at all now. Really sweet at tickover too. Can even potter along in 3rd gear at less than 1500 rpm.

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Maybe I’ve been lucky? Never had any of these symptoms either. 

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