Bad Cold Start Z1.9DT 120bhp Fault Fixed

[Danlisa]

Glad you got it sorted

Thought I had.

The first couple of days the car started perfectly, the glow plugs were on for an expected length of time during a cold start and it started first time.

Now, 3 days later, it's back to it's old ways, glow plugs don't illuminate long enough in the morning and it requires a few cycles to fire correctly.

Does a temp sensor need calibrating? Does it need operating temperatures set for it? Can something throw out or override the sensor?

Also, what is the importance of quoting a chassis number when ordering the sensor? As far as I know, my garage only quoted the Reg and model to the VX supplier.

[alcutler]

Thought I had.

The first couple of days the car started perfectly, the glow plugs were on for an expected length of time during a cold start and it started first time.

Now, 3 days later, it's back to it's old ways, glow plugs don't illuminate long enough in the morning and it requires a few cycles to fire correctly.

Does a temp sensor need calibrating? Does it need operating temperatures set for it? Can something throw out or override the sensor?

Also, what is the importance of quoting a chassis number when ordering the sensor? As far as I know, my garage only quoted the Reg and model to the VX supplier.

Hi, The temp sensor is a fixed unit that can't be adjusted in any way and does not have to be calibrated. You can only replace it and hope that it is working correctly.
The most important items for good starting on any diesel car are your battery,your charging system, ie alternator and your glowplugs. I have had similar starting problems to you on my 1.9 (120) and replaced everything, I eventually cured the problem by replacing the starter motor. Whenever i came to start the car it would always sound sluggish as though the battery was on the way out - even though it was a brand new battery and alternator fitted. On removing the starter I found the front bush on the motor was badly worn allowing the rotor (the part that turns) to bind on the stator (which is the stationary coils the rotor turns in) this was causing a massive drain on the battery as well as causing the starter to turn at a lower speed and therefore only turning the engine over at a lower speed than was needed to start it. After replacing the motor it starts first time every time whether it is warm or cold and I do not have to wait for the glowplug light to extinguish ( although I do). If you turn a diesel engine over fast enough it with start whether hot or cold even without glowplugs or coolant sensors.
Listen to your engine when the starter is turning the engine over - does it sound slow - I would consider replacing your starter - it worked for me.
Have a look at previous thread http://www.vectra-c.com/forum/showthread.php?t=159364

Hope all this helps - if I can help further please get back to me

[Danlisa]

Thanks for the reply/help.

I am reluctant to blame the starter motor as this was replaced no more than 4 months ago, due to a different fault. Even though the cold start on this car is sluggish, it's is not laboured in anyway, it just doesn't catch/fire. When I cycle the glow plugs to heat them, it fires instantly.

I also, do not believe that if the starter was at fault that the car would start fine after changing the temp sensor for about 3 days, then suddenly revert back to the initial problem/traits.

Could a thermostat that's stuck open/closed cause this starting issue? I also have an erratic temp gauge on my dash again (although it was fine for the 3 days after changing the sensor). I live/drive in the country and my morning commute is about 9 miles (country hills/roads) and my temp gauge didn't move above 70 degrees this morning. (FWIW the heater vents blow hot air after about 2 miles)

[alcutler]

It could still be the starter. By unplugging the temp sensor you are forcing the car to have the glowplugs on for longer, hence heating the cylinders up and making starting easier. If the starter is turning the engine too slow, even if it sounds ok, it is not compressing the air in the cylinders to the same degree and not creating the temperature needed to ignite the fuel. This is why other members who have changed the starter, find the engine starts easily, before the glowplug light goes out.
I am watching these threads about starters, as it seems to be helping alot of members out when they have starting problems.

Hi Barney Thanks for that - that is precisely what is happening - I am on a bit of a crusade with the starter motor issue - It cured my starting problems after months of trying/replacing everything. As you say by disconnecting the temp sensor you are causing the glowplug cycle to run longer that is heating the combustion chamber and fuel in it which does not need much compression to ignite it - so even a slow turning engine will start. If you can get any diesel engine to turn over fast enough it will start even without glowplugs.
I think what puts a lot of owners is the fact that the starter motor seems to be working ok - which was the case with me - but its the speed that it turns the engine over that is important as far as starting the engine.

[alcutler]

Thanks for the reply/help.

I am reluctant to blame the starter motor as this was replaced no more than 4 months ago, due to a different fault. Even though the cold start on this car is sluggish, it's is not laboured in anyway, it just doesn't catch/fire. When I cycle the glow plugs to heat them, it fires instantly.

I also, do not believe that if the starter was at fault that the car would start fine after changing the temp sensor for about 3 days, then suddenly revert back to the initial problem/traits.

Could a thermostat that's stuck open/closed cause this starting issue? I also have an erratic temp gauge on my dash again (although it was fine for the 3 days after changing the sensor). I live/drive in the country and my morning commute is about 9 miles (country hills/roads) and my temp gauge didn't move above 70 degrees this morning. (FWIW the heater vents blow hot air after about 2 miles)

Hi, No a faulty thermostat will not affect the starting - that does not kick in until the engine has been running for a few minutes and the coolant temp begins to rise - from what you describe - if the car was starting ok and the temp gauge was showing the correct reading - it could be that the coolant sensor is defective (it has been known for new units to be faulty) or your thermostat has failed. If the car was starting ok for the three days - it looks more like the sensor, which could also account for the temp gauge readings.
If you've had the starter motor replaced that should rule that out.

[Danlisa]

Thanks, I'll get the Sensor tested again. It's easier to rule that out and then move on.

[C-Owner]

Thanks, I'll get the Sensor tested again. It's easier to rule that out and then move on.

I always recommend a genuine GM sensor. to be fitted in case you bought a patent one.

Also did you check my first post regarding non starting number 2.

Engine wont fire first time >

2. When using multiple glow plug heat cycles.

It seems you may have a separate issue if you

can start the car first time >

2. When using multiple glow plug heat cycles.

Check the sensor anyway also check the wiring,
if your temp gauge was responding correctly for 3 days then back to the poor starting,
it could be you disturbed the wiring.
Also
I'm wondering if the ECU is registering the wrong temps from somewhere else.



.

[Danlisa]

Also I'm wondering if the ECU is registering the wrong temps from somewhere else.

This crossed my mind also. Although I don't know where else the ECU takes a Temp Reading from.

In an (possibly unrelated) issue, I tested something on the way home last night.

I turned off the cabin vents, turned the heater dial to cold and switched the internal fans OFF. Over the distance of about 2 miles, I watched as the dashboard temp dial rose to 85 degrees and stayed there.

I turned the heating back on and watched it drop to below 70 degrees.

Why would my vents control the engine temp readings?

I think I may have more than one problem here.

[alcutler]

This crossed my mind also. Although I don't know where else the ECU takes a Temp Reading from.

In an (possibly unrelated) issue, I tested something on the way home last night.

I turned off the cabin vents, turned the heater dial to cold and switched the internal fans OFF. Over the distance of about 2 miles, I watched as the dashboard temp dial rose to 85 degrees and stayed there.

I turned the heating back on and watched it drop to below 70 degrees.

Why would my vents control the engine temp readings?

I think I may have more than one problem here.

The cabin heater matrix in your car is in effect a small radiator - when you have it on full heat, cold air is forced through the heater matrix, the air is heated by passing through, and warm air comes into the interior of the car,pushed through by the fan. The air passing through also cools the coolant in the matrix hence the vehicles coolant temp falls. What you are describing sounds very much like a faulty thermostat - as the coolant temp drops the thermostat should close slightly and maintain the temp at a constant temp of approx 88 degrees.

[rioni]

I changed a temP sensor and same again i also changed a starter motor and same problem i dont know where to start changing parts i dont have any kind of error relating whith poor starting i dont know anymore what to do.