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Author Topic: staring problem tdc sensor or loom or both  (Read 2642 times)
kertrats24
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Posts: 28


« on: September 04, 2012, 11:45:02 pm »

Hi
looking for advice again i have a 2002 espace race  dci 2.2 g9t a while ago it wouldnt start i found moving or unpluging and reconecting the wire on the tdc sensor fixes it until the next time i have also found a loss of power that seems to be linked with this.
my question is should i replace the sensor or the loom that runs to it or both.?
It looks like the connector has been replaced in the past but i suppose it can go faulty again as it is very exposed.
Do you think the tdc fault will cause loss of power the car drives fine but when i hit a hill it slows down quickly and i need to change down i have cleaned the egr valve and even tried a blanking plate this seemed to help with pickup but still down on power/torque.
thanks stu
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roy4matra
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Posts: 925



« Reply #1 on: October 17, 2012, 04:33:48 pm »

Hi
looking for advice again i have a 2002 espace race  dci 2.2 g9t a while ago it wouldnt start i found moving or unpluging and reconecting the wire on the tdc sensor fixes it until the next time i have also found a loss of power that seems to be linked with this.
my question is should i replace the sensor or the loom that runs to it or both.?
It looks like the connector has been replaced in the past but i suppose it can go faulty again as it is very exposed.
Do you think the tdc fault will cause loss of power the car drives fine but when i hit a hill it slows down quickly and i need to change down i have cleaned the egr valve and even tried a blanking plate this seemed to help with pickup but still down on power/torque.
thanks stu

Hello Stu,

First I think you may have two issues not one.  A TDC problem will certainly cause non-starting issues, but unlikely to be the cause of a loss of power.  Total loss of power as in 'it won't run', but not down on power.  So IF the starting issue is the TDC, you still have another problem causing the loss of power.

First thing is to re-seat the TDC sensor and see if it makes any difference.  These are fussy engines with regard to the TDC sensor gap to flywheel.  The sensor is held by a spring clip, so go underneath, push the clip to release its hold on the sensor and push the sensor against the flywheel, and then release the clip to hold the sensor in that position.  When you start the engine it will set its own (correct) gap.  That is the correct method for setting the sensor.  Now see if it improves starting.  If it starts every time first time, over the next few days or week, you have probably cured that fault.

If however, the starting is still poor, then combined with your power loss problem which should still be there, it means the likely fault for the power loss is also causing the starting issues.

Do you have an injection warning light on or intermittently coming on?  If not, then you really need the car connected to a Clip (Renault fault diagnosis tool) so you can see all the engine parameters when it is running.  You may have a fuel pressure issue, or a sensor fault, or one of various other things that without seeing all those readings will be difficult if not impossible to diagnose.

These common rail engines need at least 150-200 bar just to start, and should idle with around 280-300 bar fuel pressure.  That is a huge amount of pressure, which is why you must never slacken a high pressure pipe when the engine is running.  If the pressure is down even a little, the starting will be poor and so will the power on the road.  It can be a poor low pressure pump or a worn high pressure pump, or very often a tiny bit of dirt stopping a needle from closing properly and causing a pressure drop on the leak-off system.  Or it could be a partially blocked fuel filter.  When was it last changed?  If I remember correctly, these have a tap on one of the pipes that is switched when bleeding the system (say after a filter change) and if that tap is not properly switched back it can cause a loss of pressure.  Or your fault is nothing to do with pressure but some other fault such as turbo boost being down on what it should.  Or oil in the inter-cooler from a leaking turbo partially blocking and causing problems; or...  See why you need to connect it and see what the parameters are telling you.  Anything else is guesswork and that could take a long time and cost a great deal before you find the problem.

So try re-setting the TDC sensor and then get the system read.

Please let everyone know the outcome as it always helps others.

Roy
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