2002 Mondeo Poor starting after short engine run

My 2002 Mondeo !.8 LX (147,000 miles) has started to exhibit very bad starting after a short engine run from cold then left to cool. I know this is a problem with a lot of cars but, up till now, it has only been a minor problem, (engine turns over for just a few more turns before firing OK). It has now become very bad and nearly wont start at all. Had the car into a very competant Bosch Dealer who has checked all the fault codes and nothing showing wrong. Plugs looked ok but we renewed them in case that was the problem. Not had circumstances arise to check if OK but has anyone any other ideas?

Reply to
Merryterry
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Fuel pressure regulator ?? Leaky injector(s) ??

David

Reply to
David

Sorry to say it, but you need to let a competent mechanic have it for a couple of days. There are many possibles, including a faulty Coolant temp. sender, air leaks, leaky injector, etc.

Reply to
Mrcheerful

Coolant temperature sensor would be my first choice. If that is stuck constantly giving a signal appropriate to a cold engine then it will start from cold but the fuel mixture will be far too rich after the engine has wamed up. Fuel consumption will probably be very poor too. The hot and cold resistance can be easily checked by anyone who knows what they are doing.

Reply to
Dave Baker

Yes I have had that on a Cavalier before but It showed up on computer fault check. In this case they ran a fault check on the computer and no faults showed up. Surely it would have shown up on that?

Merryterry

Reply to
Merryterry

How exactly do you suppose the diagnostic computer knows what the engine temperature really is and therefore what the sensor should be saying other than by going by the reading from the sensor itself?

Think about it Sherlock.

The computer can only show a fault code if the sensor is giving a reading totally out of spec or is completely broken and giving no reading at all. If it's just stuck on "cold" no one is the wiser.

Reply to
Dave Baker

I will bow to your superior knowledge but when the Cavalier Temp Sensor went down the engine ran roughly, (too rich). In this case the engine runs perfectly normally once started. In this case the only time I have a problem is if the aforementioned circumstances take place.

Merryterry

Reply to
Merryterry
[...]

Perfectly logical. It could happen with two identical make/models; there are two basic failure modes for the sensor for a start.

Chris

Reply to
Chris Whelan

Try a new set of plugs

Reply to
Rob

...

Reply to
Tony (UncleFista) Bond

Only if the person running the check engaged their brain & noticed that it's unlikely that a hot engine has a 35degC coolant temperature, rather than just shrugging and saying that there's no fault codes.

Reply to
Duncan Wood

My Ford (2003 Focus) has had occasional starting difficulties since I got it. (BTW, it has two engine temperature sensors, a cylinder head temp sensor, and a coolant temp sensor.)

I thought it was fuel related, ie: leaky injector or fuel pressure regulator, but yesterday it threw a P0340 code for the first time. This code is 'camshaft position sensor circuit'. The car runs fine when started, and is rarely tricky to start. Some more investigation is required.

David

Reply to
David
[...]

What engine?

Lots of cars only need a valid signal from the crank sensor when starting, and essentially ignore it when running.

If it was mine, I would clean up the connector for the sensor, spraying the connections with *proper* contact cleaner (NOT WD40 please!), clear the code and check after a week.

Chris

Reply to
Chris Whelan

Thank you Chris, I was just giving the OP another route to follow.

David

Reply to
David
[...]

Doh!

...*cam* sensor..

Chris

Reply to
Chris Whelan

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