Can someone tell me the exact location of the coolant temp sensor on a 1990 4x4 Cosworth. I believe it is on the back of the head between engine and firewall but cant for the life of me see it. Want to replug/contact clean conection to see if it improves an intermittant problem where car will be idling and suddenly start reving erratically and running rich (black smoke from exhaust and missing/farting about) My heater is bypassed and there is a hose running behind the engine so this may be hiding the sensor.
Also a couple of questions about reading fault codes. Does the ECU store codes from an intermittant fault like this or would I have to read them while it is faulting. Also I am guessing you cant drive around with the link in the connector for the code reading so you could read it when the problem happens.
Thanks David

 

On 2WD CTS is on inlet side at the rear of the head, behind inlet manifold, not sure on 4x4, it is a thermistor and it won't do any harm to replace it if you do suspect it's this, (They are cheap enough) being a thermistor the output can give false readings after a while. The ACT is exactly the same sensor in a different housing.

The ECU uses a flash code system for fault diagnostics, it will only log an error if a sensor goes totally open or closed circuit IIRC, once you turn the ignition off any faults that have been logged will be lost! Trouble is some remapped software does not keep this facility!

Martin

 

The ECU coolant temp sensor is in the same place as described, as well as the temp GAUGE sender on the 4wd, on the 2wd this is at the front of the near the turbo.
As said if at all suspect replace, should really be a service item imo every 3 years, due to it's importance.
tabetha

 

Thanks for that. I thought I had found it last night in the posn described hiding under a hose. I did only find one though and now not sure if it was the CTS or the temp gauge sender. It had the two pin connector with the sliding wire locking mechanism (although like a number of mine this was broken) do they both have this connector or does this prove I had the right one. The problem is when my intermittant fault happens - if you turn the car off it will not start again. When I disconnected the CTS (assuming it was the right one) the car started O.K. Any particular sensor that stops the engine starting if faulting and causes to run rich and rev up on its own. Thanks again David

 

Yes thats the one, temp gauge sender is just a single wire and has a much smaller sender

Yes the CTS is one of the most important inputs as the info it supplies will be used to determine the base level of fuel injected from freezing to boiling, I should think if you disconnect this the ECU will think it's very cold and fuel accordingly!

The hunting can also be caused by a bad TPS calibration as could the overfuelling I should think!

Martin