Cutting out when hot

I’ve just finished a mini resto on a 1991 1.6 Eunos and when the engine gets fairly hot it cuts out and is difficult to restart.
Today it cut out on me and I couldn’t restart it for 5 minutes, I did open the bonnet at this point.
I’m aware it could be either coil pack/cam angle/coolant temp sensor but is there a method for testing to try and narrow it down?
Starts great when cold.
Thanks in advance.

Hi Craig

I would discount CAS - cam and crank sensor. I would also think it unlikely to be temp sensor at rear of engine as this usually struggles for a moment between choke and normal running but unless under serious load would not stall the car.
Coilpack is a poss but these are pretty reliable on the 1.6 MK1/Eunos. Having said that I have seen some really dodgy ones recently that allegedly work!, I wouldn’t chance them for a test on my cars.
Have you done an LED diagnostic check?

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Not yet, the car cut out on me around 2 miles from home so ive left it there to cool down.
Will get it home later and do the code read.
Luckily my father in law has a 1993 model so could borrow the parts from this.

Well why not? someone’s parts and someone else’s advice. It appears to be what is it all about nowadays :slightly_smiling_face: Good luck!!

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I wouldn’t discount the engine coolant temperature sensor on the back of the head. I’ve had a case where it was the cause of an engine cutting out when hot. I was fooling the ECU into thinking the engine was still cold so the engine was being over fueled.


So pulling the codes I think I got 26 and 1.
26 makes sense, I’ve got a carbon canister delete.
1 is ignition pulse, I did find the coil pack connector not seated quite properly, it hadn’t clicked the retaining tab so maybe it was this all along.

26 is purge valve and one of two that is flagged before ignition; the other being MAF, code ‘8’.
ECU does not monitor coilpacks; ‘1’ is igniter which may well be the issue.
You have the spares available; a very easy swap to test.


Took it for a good run today and got it nice and hot and it didn’t miss a beat so I’m hoping it was a poor connection at the coil pack.
Will keep the spares in the car just in case!

Hopefully that is it:-)
The coilpacks are not monitored but perhaps the failure of the igniter to connect with the coil units on your MK1/Eunos 1.6. is?
All other MX5s, MK1 1.8, MK2 and MK2.5 have coil units with built in igniters.

I’d guess as it’s not firing correctly it logs the code 1 as it’s not that intelligent a system.