RE: 87 4KQ engine problems - fixed!

["Bruce Bell" <bbell04@ibm.net>]

First thing to check whenever you have cold starting problems. Common
failure and cheap and easy to diagnose and fix. BTW yours failed to "close"
(too much resistance). This is the worst as it can destroy the cat in short
order . They can fail to "open" as well (no resistance and too lean). This
is the only part, other than normal wear items, which has been replaced more
than once on my car in 230K Miles.

Bruce
87 4kq

> Thanks to all those who responded to my rough-idle problem. The fault
> was in the coolant temp. sensor and not the OXS sensor after all. The
> temp. sensor was an open-circuit with the engine cold (20 deg. C). I
> guess the fuel-injection system thought it was sub-zero, making the
> mixture very rich. The system must not be smart enough to be able to
> tell that the sensor has failed and put the mixture setting
> somewhere in
> the middle of the range. A replacement sensor measured about 2700 ohms
> with the engine cold.
>
> Craig Parkin
> 1987 4KQ 236,000km
> black with no more black clouds trailing
>
>
>