Streetlife Posted February 17, 2002 Share Posted February 17, 2002 Started having a bit of a problem the other day on a decent drive from Wiltshire to Guildford. Car had been behaving perfectly on the way there but on the way back was getting lumpier and more sluggish when pulling away (VW Sharan beat me on a roundabout). Problem got worse for the remainder of the journey with the engine starting to hold high revs of its own accord (throttle cable not sticking) and running on for several seconds after the ignition was switched off. Day after it refused to start completely. Replaced plugs, dis. cap, rotor arm and checked tuning but without result. Checked compression ratio and was seeing 13 or 14 rather than the 9.5 quoted (could be a duff compression meter but it is brand new). Shone torch in cylinder and piston looks smooth and grey, rather than heavily coked up. All cylinders about equal, no sign of leaking valves. Carbs seem OK, jets all nicely clean, nothing sticking, fuel spurting out as it's supposed to. Timing is correct. Engine is 1700 and has done about 9K miles and was a recon with unleaded conversion in 1990 when Caterham had the X-Flow shortage (so I'm told by various sources). Has been rolling road tuned in the past with all the expected performance figures achieved. Looking for pointers because I've exhausted my limited knowledge! Thanks in advance nick Edited by - streetlife on 17 Feb 2002 18:17:35 Link to comment Share on other sites More sharing options...
Paul Drawmer Posted February 17, 2002 Share Posted February 17, 2002 Some guesses from a hammer chewer. I would think that maybe you have either a fuel starvation or an inlet air leak. The running-on and hanging onto revs, sounds as if there is a very weak mixture causing the plugs to overheat and then effectively 'glow plug' after you have switched off. If I'm right, you are in danger of doing damage to pistons etc with excessive internal temperatures. Your compression meter will measure the pressure in the cyls, not the compression ratio. Hopefully you will get some better answers than my guess. Link to comment Share on other sites More sharing options...
Roger King Posted February 17, 2002 Share Posted February 17, 2002 I think that Paul's suggestions are sensible. If you are sure that hanging onto high revs is not throttle cable related, an air leak may indeed be part of the problem. Check the carb mounts are in good condition and make sure none of the carb mount studs have fallen out. Additional thoughts are that your throttle linkage may have come adrift causing severely out of balance carbs and possibly a stuck throttle. Or your ignition system may have suffered from the usual rotor arm failure that causes the timing to go haywire (assuming that you have the Caterham supplied system that was notorious for problems like this). Link to comment Share on other sites More sharing options...
Streetlife Posted February 17, 2002 Author Share Posted February 17, 2002 Paul, did find a damaged O ring on the inlet manifold and replaced that (and all the others) first. As an update, it did start later today. Tuned it up, seemed to idle OK so went out for a run. Lumpy in low revs, smooth at higher revs and sluggish when pulling away. Stopped to buy a paper and..... wouldn't start again. Could only get it going by bump starting down a decent hill. Died as I arrived home with flames out the exhaust. Nick Link to comment Share on other sites More sharing options...
Streetlife Posted February 17, 2002 Author Share Posted February 17, 2002 Roger, studs etc. all OK. I've had various problems with the ignition in the past (vane switch shorting and the like). I'm going to replace the vane switch and rotor arm following your suggestion. Any recommendations on a replacement to the standard Caterham supplied ignition system? thanks Nick Link to comment Share on other sites More sharing options...
Paul Drawmer Posted February 18, 2002 Share Posted February 18, 2002 Ahh - was just having my morning coffee - and your posting re-appeared in the brain. I thought - the timing may have advanced itself - poor running, overheating etc. Find that the proper Guru has already suggested it. Now I will watch this thread and learn..good this stuff innit. Link to comment Share on other sites More sharing options...
philwaters Posted February 18, 2002 Share Posted February 18, 2002 Hi Nick, I had very similar problems on my 1600 X/flow and found it was the timing. I set off to a pub meet one evening and it was fine to begine with and as the trip went on it got worse (I was beaten by an MX5!!). Once at the pub we balanced carbs etc etc and it was the same on the way home. The only other thing mine did was to try to die when you lifted off the revs, like approaching a rounabout, and need blips of throttle to keep it from stalling. When we got a timing light on it we found it was basically showing 0 degrees. A quick rotate of the dizzy and all was well again. I found it very odd that it could just loose it's timing over such a short distance, especially as I had never touched the dizzy before so the bolt should have been tight. After that it became a routine check every couple of weeks. Phil Waters Zetec is in and running wink.gif Link to comment Share on other sites More sharing options...
Taran Las Posted February 18, 2002 Share Posted February 18, 2002 Streetlife, I changed my ignition system to a Lucas Competition ignition purchased from Roger, monster spark and a doddle to fit. Well worth the money. Regards Phil Owen. Link to comment Share on other sites More sharing options...
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