Honda EV1 / EW1 / EW5

Honda's engines of the early and mid 1980s — the EV, EW and ZA fours, and the 2.0 A20A — in the Civic, CR-X, Accord and Prelude.

These predate almost everything a modern technician expects. Most are carburetted, several use Honda's CVCC three-valve stratified-charge head, and the engine management where it exists is rudimentary. There is very little to read with a scan tool and nothing to read at all on the carburetted ones.

So diagnosis is physical. Compression, vacuum, ignition timing with a light, and fuel delivery measured rather than inferred.

The CVCC carburettor is the part that makes these hard. It is complex, it has a great many vacuum hoses, and most running complaints on a surviving car trace to perished hoses rather than to the carburettor itself — which is worth establishing before anybody opens it.

Very few of these survive, and parts are the practical constraint on all of them.