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MG TD TF 1500 - Engine misfires after idle

Can anyone suggest where I should look for this fault?
After a few minutes of idlying in stopped traffic I have a misfire which clears within a couple of minutes of driving.
The temperature gauge shows normal.
The other night after a few traffic hold-ups the usual misfire started only this time it refused to clear.
I changed to a spare coil, checked the point gap ... all ok, then after about 20 minutes she cleared and pulled as good as ever.
I was wondering if it was fuel related, ie vapour lock from the exhaust manifold perhaps, I don't have a heat shield.
Any suggestions?
Cliff Harvey

Vapour lock only happens after a shut down, and a hot restart a few minutes later,,,, it will not happen whist the engine is running,,
I would think that it is running a bit rich at a low idle,, Try to make if happen in a parking lot,,, when it does happen, shut it off, and check all the plugs,, they might be black and fouled,,,
How many miles are on the plugs?? Are they gapped OK??

Steve Wincze

You might replace your ignition condenser. I had a similar misfire situation after I replaced my condenser and points. It got progressively worse. I, too, suspected the coil, then the plugs, etc., because the points and condenser were NEW! Turned out to be the new condenser, and I had already tossed the old one. Hint: DON'T order a condenser from Moss. I managed to pick up a NOS condenser from a friend that once owned a Brit car shop. Online suggestions were to get a 1978 Plymouth Arrow 1.6L condenser at NAPA or Advance. I had already gotten my NOS one, but the Arrow piece is far less expensive.
Frank Bice

Steve, the plugs are gapped ok and have 3,000 miles on them, I'll certained have a look next time and check their condition, in the meanwhile I'll try Frank's idea of a condenser, it's just that I find it puzzling that it clears itself after a period of time, do condensers do that?
Cliff Harvey

Are you sure your SU's have the correct amount and type of oil in the dampers?

Jim B.
JA Benjamin

Dont fall into the trap of adjusting carburetors, 99% of issues of this nature are ignition related.
G Evans

Seems like we are experiencing condenser problems more and more. I wonder if it could it be the result of the influx of those made in the Far East?
Jim Merz

Jim the dampers are full (with 3 in 1) and the condenser is an old original one, perhaps it's come to the end of its life, I'll try a replacement and let everyone no the outcome, thanks for the ideas.
Cliff Harvey

One thing I believe we all can agree on is,, if you change or adjust too many things at once, and it clears up, you won't know which change or adjustment made the difference!
Sooo, go through the routine that makes it fail,,
Change or check one thing,,
If it still fails, try the next idea,,,

Steve Wincze


Applying a little more grey matter to your problem I am wondering if it might be voltage related. At idle your geny will not be producing, if you have a bad connection in either the primary or secondary ignition circuits low voltage will come into effect. You have inferred that when the engine revs are up, geny operational, the fault clears, this has led me to this train of thought.

Some quick voltage checks of the voltage at the points with the engine stationary might provide some clues.

G Evans

Check your battery voltage. When the engine is idling, the generator is not charging, so voltage dips significantly. A weak battery will provide a weak spark, ESPECIALLY with headlights on.
For example, the other night, before we left for a long night trip, I put the battery charger on it so our good batteries were supercharged. Even with great batteries, long stop & go through stoplights can be a real drain, even with our HID headlights that only draw 35 watts.

This thread was discussed between 04/11/2014 and 07/11/2014

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