Problem with my Prelude

Heres a curly one, it's got me completely stumped.

I have an 89 Prelude, twin carb. (S model in the states, XX everywhere else).

It will start and run fine untill it warms up, then all the ignition simply dies.

Either something is over heating and stopping, or the something is killing the ignition when the temp sensor reachs a certian point.

It has fuel, but there is no spark from the coil.



The car is currently stuck some distance from home, so any help would appreciated.

could be as simple as a bad coil. Sometimes as they start to fail they'll only work when their cold, but they fail as they get warm.

Try testing the resistance across the primary and secondary both when its cold and hot. My guess is that the resistance is much higher when its hot.

That was my first thought, so I put a new coil in, started it up, and thought yay! Easy fix.

Then it got up to normal operating temp and died.

Should have mentioned that :)

Have you tried pulling a wire off the temp sender?

Have you tried pulling a wire off the temp sender?

I un-plugged it, but it made no difference.

Does anyone know if shorting it will tell the car its still cold, and prehaps let it run?


After reading the service manual: http://media.honda.co.uk/car/owner/media/manuals/PreludeManual/index.html

And apparently there are two different ignition controls for cold and warm running.
Since the car runs when cold, but just switches off once warm, I'm guessing there is a problem with the warm system.

If I can convince the car it is still cold, when its not, I should be able to drive it home before it fouls the plugs from running rich.

The temp senders I've played with had high resistance when cold and lower resistance when hot. The temp gauge was simply an ammeter which reads the current through the temp wire. The voltage supply is in the instrument panel, the earth in the engine block.

Shorting it (you'll want a resistor in there) will give you a high temp reading.

Shorting it (you'll want a resistor in there) will give you a high temp reading.


So leaving it open, unplugging it, or shorting it with a low resistance, should tell it it's cold?

It might be safer to pick up a used sensor from the wreckers tomorrow and tape it up in the engine pay somewhere cold :)

So, I had a chat with a mechanic mate today, he says there are 3 temp sensors in the car.
One for the gauge, one for the fan, and one for the ECU.

He thinks its possible the one for the ECU is shorting at a certain temperature, sending a bad signal to the ECU which is then shutting down the car.

Tonights mission, when I get to the car, is to find that sensor and un-plug it :)

Low resistance = hot.
High resistance = cold.
Broken circuit = very cold.

Carbs and ECU? Sounds like you've all bases covered.:grinyes:

Carbs and ECU? Sounds like you've all bases covered.:grinyes:


Honda thought they could be clever and combine the two, then use vacum to control it all...........