1.6L temp warnings

[Guest]

The temperature gauge on my 1.6L Montego has been acting up for a while. It goes straight to 'overheating' with the light flashing. This also means the autochoke doesn't speed up the engine, although it is cold. Usually it corrects itself after a few miles, but it can happen any time, when restarting, or even while driving. It is definitely not overheating. I have changed the temperature sensor in the block for a new one, tried different ecu and fuel ecu (not new but ok in the other car). I had almost become resigned to it. Then yesterday it took a different twist. I drove 20-odd miles with the temperature gauge not registering at all - it just stayed on cold. The heater was working ok. When I restarted after a stop, there it was, flashing 'overheating' again. It's so annoying. I have previously tried unplugging the fuel ecu, cleaning the contacts etc, which may have made it a bit better. Is there anywhere else I can look?
Apart from the collapsed head lining, this is the only fault on this car, so it would be really good to correct it.

[steve smith]

sounds to me like the wiring have u tried another ecu as i had same trouble with minde till i changed the ecu again for a new one or it could be the connections on the back of the dails i had that years ago.

[E_T_V]

The fuel ECU is the likely suspect as it drives the gauge.

Cleaning up the contacts on the fuel ECU may help (maplins etc sell contact cleaner in aerosol tins), but often plugging and unplugging it in several times will do the job.

[G Force]

I have changed the temperature sensor in the block for a new one,

Hi RobertP, I am sure you mean the correct sensor, but just wanted to confirm you had changed the coolant sensor in the thermostat housing on the end of the cylinder head, and not the knock sensor in the centre front of the engine block. That would be too easy a solution though

Is there anywhere else I can look?

There are a few other things you can check.

Check the large multi plug connection on the N/S inner wing under the bonnet close to where the loom goes through the bulk head. Pull the plug apart and reconnect a few times, and check for corrosion and poor conections, close up all the female connections to give a tight fit. If the plug is filled with grease clean it all out with electro cleaner and repack with vaseline or other grease suitable for electrical connections. If you have a multi meter check for continuity / short circuit in the wiring between the sensor and ecu on the pink green and pink black wires.


Check the earth points on the car are clean tight and not corroded, There are points on both front bumper mounts, battery tray, and on the N/S A post, you need to drop the glove box and find it with a torch.

If you have no luck it is possible the temp gauge its self is malfunctioning.

Cheers

[Guest]

Thanks for all your suggestions. The forecast says dry all week, so I'll have a look tomorrow. (we need an 'eternally hopeful' smiley for all M&M owners!)

[Guest]

Well, it is tomorrow and the sun has come out. So far I have found, unplugged, cleaned, replugged and jiggled the multiplug near the washer bottle. I have also changed to yet another ecu, which looked nice and clean, and cleaned the plug which ..er.. plugs into it. I have removed the battery and cleaned the tray, which looked a bit rusty, though probably that wasn't a major factor. But you know how it is. The car still starts ok, runs ok, and the temperature guage merrily goes up and down as it pleases. Perhaps it is the guage, but I am very reluctant to rip all that stuff out just on the off-chance. However, I have just discovered a glove box lid complete with fuel ecu that I had forgotten I had. So, after this coffee and jam tart break, I'll try replacing that (again). It does strike me that the wires above the glove box are very scrunched up, and this is probably not ideal. I'll look again for poor connections, and keep trying. Rhetorical question: is anything more annoying than a machine which does not do what it was made for, with no apparent reason? Grr.
btw, yes, it was the temperature sensor near the distributor that I replaced. There is a shop in Worthing that was selling off a lot of Maestro/Montego spares, so this was one thing I actually bought new, not salvaged from a scrapper.

[Guest]

...later
well, the jam tart did its job. I replaced the fuel ecu with the one I found in the drawer, after cleaning all the contacts, and now the car runs perfectly, for the first time in about three years. Starts instantly, ticks over fast while it is cold, the temperature warms up a lot more quickly, and the tickover slows down after a minute or so, as the guage moves off the stop. I had forgotten what a nice car it is to drive.
Thanks to everyone for your advice, suggestions, and moral support.

[E_T_V]

Glad it was a simple fix in the end.

[daveyboy]

Great news Robert i trust this is on B322SNX? Glad you have sorted her out i hope apart from this she has been good to you since you had it off us

[G Force]

Hi RobertP.

Gosh how unlucky to find 3 out of 4 ECU's faulty, I think that is testament to the unreliability of that part of the ECU. It does on the other hand re-enforce what has been said about the fuel ECU being the most likely culprit for causing the set of symptoms you have described.

Glad to hear that the car now drives as it should do now. On a note of optimistic consolation for the hours spent checking and cleaning connections and earth points etc. it can never be time wasted as so many niggling little faults are due to problems in these areas, and I would not be at all surprised that along with the good ECU if they were not in part helping to contribute to how well the car now runs.

Fingers crossed now for a good few years of trouble free driving.

Regards, Gforce.