Berlingo 1.4 Petrol 2000

[Jate]

Any ideas on this problem?
Cold engine starts instantly and runs smoothly for 5 minutes or so.
Then one cylinder goes missing.
I guess from that that it's a heat-related problem.
Above 3000 revs the engine seems smooth again. (But this might simply be because, at high revs, the missing cylinder is undetectable.)
New plugs were fitted. No improvement.
Once cold, and started again, all four cylinders run smoothly, again for about 5 minutes.

The garage thought it wasn't the coil. Are they right? (The coil sits on the engine and so heats up, doesn't it?)
They suggested it might be valves but said the cost of further investigation wasn't worth it at 20 years old.
But everything else is fine on the car. It seems a pity to scrap it.
Any ideas?

[PontyAl]

Hi Jate.
It would be a shame to scrap the car for a misfire, it doesn't sound like valves, more likely a HT issue from your description. I'd definitely try a coil, or HT leads, cap etc but any OBD2 diagnostic tool should point you in the right direction if you don't have access to lexia diagnostics.
Hope you get it sorted.
Cheers.
PontyAl

[wheeler]

This is screaming out coil fault to me.

[Jate]

Thank you both for your encouragement and replies. We'll pursue the coil and HT leads further.

[Jate]

Hello again
Citroen Berlingo 1.4 Petrol 2000
Engine starts smoothly and runs smoothly for a few minutes then one cylinder misses. I took your advice and, as a test, got a secondhand coil module and fitted it.
But now we find that the car's wiring connector won't go into the socket on the new module even though it looks identical to the old one.
It's identical except for a very small plastic lug in the socket of the new module which prevents the car's plug going fully in.
Are there incompatible versions of the same model?
Such a small variation in the socket seems to indicate some designed incompatibility?
Any suggestions please? e.g.: should we simply cut the obstruction off and carry on?
Thanks again.

[CitroJim]

Any suggestions please? e.g.: should we simply cut the obstruction off and carry on?

Whilst I'd agree the coil is a very likely candidate I'd not risk modifying the replacement to fit... There is a reason and unless you know precisely the coils are identical bar this 'obstruction' you risk potential ECU damage.

A damaged ECU as a result may make the vehicle uneconomic to repair so proceed with caution.

Before condemning the old coil, have you had diagnostics performed? It's worth it if not as a malfunctioning coil will often throw up a fault code and therefore confirm the diagnosis.

[admiral51]

It is only a personal opinion but you state you have got a second hand part that does not seem to be compatible, not knowing the cost for a new replacement part i would personally go for a new part not a second hand part when it comes to the ignition/coil part of the system.

Colin