A very annoying problem

[pena]

Am experiencing a weird problem with the car.
Last night the engine cut out on me at the traffic lights.
Tried to re-start, but no joy.
Waited about 15 seconds restarted the car, and it started up again.

Then for the rest of the trip home, everytime the engine got hot, the car behaves as if it running on 4-6 cylinders.

However it idles perfectly and drives fine up to about 2500 rpm, then it starts jerking like mad.

This only happens when the engine is hot and the fans are about to kick in.

I have checked that all the HT-Leads are connected properly, and they are.

Anyone know what the hell is going on?

Could it be the ignition amplifier ?

[GreenV8S]

Could be, but there are various other things that might be causing it. If you can reproduce the problem a decent sparky ought to be able to track it down fairly quickly. If you want to diagnose it yourself I'd start by putting a passive strobe in series with the king lead and follow the problem from there.

[petros]

Had that happen on my 4.6 MGB and it was the Dissie.Peter

[bugsy]

I had a similar problem before and it turned out to be the coil, it started with starting to cut out over 2500 revs but ticked over ok and eventually died all together.
Maybe worth checking, the easiest way I found was to try another coil.

[pena]

Boy, just had to drive it back from west end to surrey.
It drove fne for half the journey,nohiccups at all,then I got into a little traffic and after about 2 mins it cut off.

Waited a minute started (Started first time).
Got on the M-wayand hooted it all the way home.

Was perfect.
Parked up,let it runfor 10mins,hot and off again.

What a headache.
I will change the coil in the morning,hope it fixes the problem.
I don't need any more huge bills this month.

[M808CLR]

I recently experienced a similar problem and tracked it down to the Foxguard alarm. I found that the engine cut out completely from time to time with no warning and with no regularity. The alarm system immobilises the car by cutting power to the fuel pump and with a faulty alarm, power was intermittently applied to the pump circuit also causing misfire characteristics. I had to replace the immobiliser system but it cured the problem straight away. Have a word with Carl at Car and bike Installations www.tvruk.tv, he should be able to point you in the right direction.

[chicklets]

check the coil, happened to me with my Chim, heat affect it alot, but once you are on motorway, miraculously it fires up all the cylinders again...

you might also get a faint whiff of petrol as it's unburnt...

[ggt]

bugsy said:

I had a similar problem before and it turned out to be the coil, it started with starting to cut out over 2500 revs but ticked over ok and eventually died all together. Maybe worth checking, the easiest way I found was to try another coil.

ditto, see if you can borrow one , might save you a few bob in the long run.

[stringbag]

I have a known good spare coil. If you are down this end of the world you are more than welcome to borrow it.

[tpo]

The bible suggests that coils are prone to break down when hot particularly if leaking oil. I had this on a Norton twin where the coils are above the exhaust. They were fine when moving but a bugger in traffic.

>> Edited by tpo on Wednesday 1st June 17:17

[pena]

stringbag.
What location are you ?
Am in surrey.

[stringbag]

Sorry Pena, just seen your reply. Live in Bath, but work at Heathrow, so anywhere down the M4 is good for me if you are still in need of a coil.

[Wildfire]

Yep definitley sounds like the coil as when they are on the way out they degrade when getting hot. Happened to my S3.

[pena]

Oh..
No worries, problem fixed now.
It turned out to be the ignition amplifier.

[stringbag]

Good to hear. more , less!