luukkala Posted May 25, 2015 Report Share Posted May 25, 2015 (edited) Hi, Asking some advice... The issue has been on for some time, but last weekend I just had enough of it... Starting my 1974 TR6 PI as cold, the engine works perfectly in all conditions: cold start normally choke on, and all cylinders firing perfectly in all driving conditions. But, when the engine is hot, say after 30 min driving, the nightmare begins: every time I stop in traffic lights or junction and let the engine to go idle, the engine works well in idle, but when then engaging the clutch and giving more revs to move on, the engine doesn't have all cylinders firing. When traffic light turns green, I need to stay stand still and collect revs before lifting the clutch and get going, even then the car sounds like tractor as not all cylinders are firing properly. Only after I have enough revs (roughly above 2500), all cylinders are fully firing, which usually happens after 100 meters leaving the traffic lights. Because of the issue, leaving traffic lights is not fast, nor smooth at all. Any advice where to start troubleshooting? Is this a problem wih dizzy or with the PI system, or something else? The engine works perfectly on idle in every conditions, even in hot. Similarly, no probs in higway speeds at all. Anyone else faced similar issue? Engine data: otherwise stock engine, but contacts changed to Lumenition Magnetronic system and engine head conveter to unleaded fuel. Cheers, Tommi Edited May 25, 2015 by luukkala Quote Link to post Share on other sites
Sapphire72 Posted May 25, 2015 Report Share Posted May 25, 2015 One possibility is that the fuel mixture is too rich, and could be fouling the spark plugs. An easy place to start would be to pull all six plugs to note their condition. If you choose to do so, post a photo for all to see the plug tips. Quote Link to post Share on other sites
marki Posted May 25, 2015 Report Share Posted May 25, 2015 Stick it back on points, I had a very similar issue which I chased all over the car replacing lots of stuff, since putting it back on points all well. Good luck Mark Quote Link to post Share on other sites
Peter Cobbold Posted May 25, 2015 Report Share Posted May 25, 2015 Tommi, I think the sprak might be too retarded, when hot. It seems to need to get to 2500rpm - when the centrifugal advance is nearly complete- to run. So set the static timing to 11-12BTDC. Like Mark above I am not a fan of electronic ignition. Fibre-heeled points ( from Distrubutor Doctor) with little molygrease lubrication are my choice. Perhaps heat is affecting the electronics. Peter Quote Link to post Share on other sites
luukkala Posted May 25, 2015 Author Report Share Posted May 25, 2015 Hi, Going back to the points would mean changing the whole distributor as mine is modified one. The little pin pointing up and holding points mechanism is taken out, therefore not an easy option as such (my distributor is actually from older TR6), just remembered. Peter, you mentioned heat impact... that would sound very logical as the problem comes after 30 min or so driving and like it happened last weekend, the problem was the worst when driving in city areas, low speeds, lots of stops. The Lumenition system has been in place for 15 years in my car. So far I've been pretty happy about it, and it has been very, very maintenance free, but could be indeed that it has reached the end of its life cycle. I'll check the spark plugs as well as suggested above, but I'm in doubt this would be the issue given the problem only comes when the engine is hot. But let's not leave any stones unturned... If I need to go for a new distributor, is the best option standard one for a standard engine like mine? I believe I can find another posts and discussions on that within this forum anyway. Tommi Quote Link to post Share on other sites
peejay4A Posted May 25, 2015 Report Share Posted May 25, 2015 (edited) I had the same symptoms with Lumenition failing when the aluminium control box got hot in slow traffic. I proved it in the garage with a heat gun. Edited May 25, 2015 by peejay4A Quote Link to post Share on other sites
Peter Cobbold Posted May 25, 2015 Report Share Posted May 25, 2015 Tommi, Distributor Doctor sells new contact breaker plates - maybe for TR6 disys: http://www.distributordoctor.com/ Peter Quote Link to post Share on other sites
Peter Cobbold Posted May 25, 2015 Report Share Posted May 25, 2015 I had the same symptoms with Lumenition failing when the aluminium control box got hot in slow traffic. I proved it in the garage with a heat gun. Now that's definitely a diagnostic trick to archive for future use. If/when the archive happens. Peter Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.