View Full Version : TR4/4A TR4A Engine Misfire?

04-17-2006, 11:24 PM
#1 cylinder ignites fuel sporadically. No vacuum leaks that I could find, new Pertronix. There is firng at #1 cylinder,however with engine warm and idling , you can disconnect #1 plug wire and their is no change in the idle. The engine runs strong under acceleration but when held to constant rpm, it tends to rock the car back and forth a little , I'm thinking it's igniting the fuel sporadically. It does this at all rpms , just more noticeable at lower speeds. What do yall think the problem might be? Also, new spark plugs ,ignition parts new, carbs check ok, verified the spordic flaming with the colourtune system. All the other cylinders igniting correctly.

04-18-2006, 06:00 AM
Charlie, are you familiar with Jim the mechanic over on Cameron St.? Coming from Amb. Caffery, turn right on Cameron and look, after a few blocks, on your right. Jim ain't much to look at (looks like a Harley dude) but really knows British sports cars and won't remove your eye teeth. Probably worth your time to buzz over there and have him look at your problem. I have used him off and on for 20 years, knows some stuff.


Andrew Mace
04-18-2006, 09:19 AM
Personally, I'd be a bit suspicious of either the #1 spark plug or #1 lead, even though new. What about swapping plugs with another cylinder and seeing what happens?

04-18-2006, 09:43 PM
Thanks Bill for the Mechanic info,I'm sure it will come in handy for me. Andrew, changed plugs with another cylinder and also the plug wire, no change. It must be a mechanical problem because I verified firing using the colortune, only on #1 cylinder it showed an intermittent blue flame, #2,3,&4showed a consistent blue flame at idle. #1 cylinder is igniting the fuel every so often even though it has a consistent spark. Must be valves, rings, valve springs, whatever. Does anybody have any theories about what is happening in #1 cylinder? Thanks , Charlie

Andrew Mace
04-18-2006, 09:51 PM
Time for a compression check, and possibly also a check for leaks around the intake manifold and carbs?

04-18-2006, 10:12 PM
Yep, compression check would be a very good and easy diagnostic. Another fairly painless thing you could do is pop off the valve cover and see if at least the valves are moving properly before you get more serious.

But maybe this still could be electrical - hows your distributor cap and rotor? Switching wire and plug won't fix that if the problem is internal to the distributor.
Good luck!