Hot splutters

[Ernie Arnold]

Any suggestions or thoughts on the following :
Stag (Auto) has done 89,000 miles (50,000 since major rebuild works 15 years ago) It has been rallied most years with no problems or overheating during very hot summers in Spain & France. Always runs well and trouble free. When cold runs well and power is normal for acceleration and running. The last rally in July as day temperature rose above mid 20's towards the 30 deg C the car hesitates, almost splutters and slowly picks up. Also stalled if stopped. Keeping the rev’s up helped a bit, and once moving with couple of thousand revs seems normal power, till foot down and splutter / hesitation back.
Engine temperature slightly above normal (as expected with high air temp, but well within limits). All plugs looked uniformly healthy when removed.
Question – is it a fuel or electric problem. It feels like it could be an electrical component breaking down (coil/ luminition capacitor / HT leads?), but which? The car has run OK previously in v hot weather so tend not to think its fuel starvation / air lock.
Comments / suggestions welcome on cause (checks) before I start replacing bits. Problem is it needs to be v hot to confirm its fixed. Thanks in advance for any feedback.

[wilf]

Lumenition triggers can behave like this, but first check the (three cables?) connector to the lumenition box - the internal connectors can become prone to going o/c especially in heat.

If that's OK, then I would suspect coil.

Does the tacho flicker during the misfire?

If none of the above, then it might be heat soak into the fuel lines giving vapourisation. What cooling fan(s) do you have?

[Stagsongas]

Ernie,

All you can do is choose between fuel and electrics as a place to begin, follow that path and prove / disprove the theory.

After suffering a very similar problem with my car it will be no surprise to anyone that I'd bet on an overheating coil, but as I don't run my car on petrol I had a head start, it could not be fuel. To prove one way or the other is easy, carry a spare, cold coil. Connect it up temporarily when it misbehaves and then see what happens.

Good Luck

Steve

[Bob Heritage]

Hi Ernie, Good to hear from you again. We have our club night this coming Tuesday, I'll be happy to have a look for you.

Bob

[GDPR]

Try extending the wires and HT lead and mount the coil off the engine

[Ernie Arnold]

Hi Bob,
Good to hear from you. Tuesdays always difficult for me as since so called retirement have started Tai Chi club. Tuesdays I teach. I keep reading the magazine too late for the events but will make one soon. All the best Ernie

[Ernie Arnold]

Thanks Wilf,
I will replace coil, overhaul the Lumenition and maybe replace the HT leads.
Tacho was steady and no extra cooling fan just the standard.
I will post results. Thanks again. Ernie

[Ernie Arnold]

Thanks for reply Steve,
I need a "reply all" for this posting.
I will replace coil, overhaul the Lumenition and maybe replace the HT leads. Wait for hot day and post results.
Thanks again. Ernie

[Stagsongas]

Thanks for reply Steve,
I need a "reply all" for this posting.
I will replace coil, overhaul the Lumenition and maybe replace the HT leads. Wait for hot day and post results.
Thanks again. Ernie

Ernie,

None of those can be time or money wasted. Keep your old coil though, in the boot. That could be the cold one to simply connect up to see if the engine runs when it won't, if that makes any sense.

Good Luck

Steve

[Ernie Arnold]

Replaced coil / HT leads / rotor arm / distributer cap. Positively purring now - running smoother at all speeds.
Thanks to all for replies. Ernie