I sold my old A2 1.4 TDI to a good friend a couple of years ago... He loves it (I've now got a newer one, so everybody's happy) but recently it's developed an occasional problem... It always starts when cold, but sometimes, having warmed up properly but then briefly stopped, it just won't start. My mate just has to wait in the car, trying it every 5 mins or so, and then it'll eventually get going again, sometimes after as long as half an hour... He's had a diag test at his local (non specialist) garage, but as it's intermittent, no fault has been diagnosed. Has anybody got any ideas? Thanks...
intermittent starting problem
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- intermittent starting warm
It may be a cank speed sensor problem - http://www.a2oc.net/forum/showthread.php?21120-Starting-issue&p=163736#post163736
Cheers Spike
Cheers Spike
Foghorn
Member
I'm reseraching my problems of poor hot starting and figure ite either the crankshaft or camshaft sensor. I get the impression if it was the crankshaft the engine would run poorly once fired up whereas the camshaft (CMP) sensor is only used on start up. Here is a write up from a Rover forum:
Camshaft Position (CMP) sensor
The CMP sensor is located on top of the engine on the camshaft cover. This sensor is a Hall effect sensor producing
one pulse for every camshaft revolution. The CMP sensor is only used on start up to synchronise the ECM programme
with the CKP signal. This is to identify number one cylinder for correct injection timing. Once this has been achieved
the input from the CMP sensor is no longer used in any of the ECM strategies.
Electrical input to the CMP sensor is supplied via the main relay located in engine compartment fuse box. One output
is sensor earth, the other is the signal output to the ECM.
In the event of a CMP sensor signal failure the engine will crank but will not start.
Camshaft Position (CMP) sensor
The CMP sensor is located on top of the engine on the camshaft cover. This sensor is a Hall effect sensor producing
one pulse for every camshaft revolution. The CMP sensor is only used on start up to synchronise the ECM programme
with the CKP signal. This is to identify number one cylinder for correct injection timing. Once this has been achieved
the input from the CMP sensor is no longer used in any of the ECM strategies.
Electrical input to the CMP sensor is supplied via the main relay located in engine compartment fuse box. One output
is sensor earth, the other is the signal output to the ECM.
In the event of a CMP sensor signal failure the engine will crank but will not start.
Similar info from the A2oc - http://www.a2oc.net/forum/showthread.php?20520-Help-camshaft-sensor&p=156838#post156838
Normally a failing crank sensor will cause the engine to cut out whenever it gets hot so other things to consider are problems with coolant or fuel temp sensors
Cheers Spike
Normally a failing crank sensor will cause the engine to cut out whenever it gets hot so other things to consider are problems with coolant or fuel temp sensors
Cheers Spike
jonbad
Member
Purely based on the description of symptoms, it sounds to me like it could be the coolant temperature sensor (in agreement with Spike). Also cheaper to replace than the CMP sensor as a first try. Though my car is petrol, it had exactly the same symptoms as you've described (of sometimes not starting when warm - intermitently) and also did not show on any diagnostic. That said, I was sent a faulty one initially - failed after a month - but that time it did show up on the diagnostic as something along the lines of "temperature sender signal too high" or similar such term.
Lastly, it's not likely to be earthing points unless the problem happens at any temperature - but it was suggested to me to take a look at mine (at the base of the A pillar on the inside of the car - forum search for it!). A relatively easy inspection and something worth ruling out; without any cost too!
Lastly, it's not likely to be earthing points unless the problem happens at any temperature - but it was suggested to me to take a look at mine (at the base of the A pillar on the inside of the car - forum search for it!). A relatively easy inspection and something worth ruling out; without any cost too!