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Discussion Starter · #1 ·
Despite numerous repeat visits to two French Renault main dealers over the last year, my RX4 still periodically (ie at least once a fortnight) refuses to start. The Ignition switches on and the engine turns over OK, but it won’t fire up. It has also occasionally suddenly stopped, eg after hitting a speed hump a bit too fast! The ‘no start’ fault can occur both with the engine cold, or hot after an otherwise smooth run.

This problem was initially – and several times subsequently – put down to a duff TDC indicator module. This was changed (for €160!) but the fault kept recurring. Then the TDC indicator wiring to the EMS(?), or a connection along it, was blamed, so the wiring and connectors have been changed – twice - (another €70; 2nd time uner warranty), but still..... And of course, when at the garage, the Diagnostics tests never show up any problem!

I then learned from a very helpful EuropAssistance man (called out to yet another ‘no start’) that if one reaches down into the engine bay and gently ‘jiggles’ the wires near the TDC module, the engine fires up as soon as the ignition key is turned again. So as the Renault dealer ‘experts’ have failed me, this is now my standard practice on such occasions!

Problem is, my wife can’t/won’t drive the car alone, as she wouldn’t be able to reach far enough down into the (most likely, hot!) engine bay to reach the TDC wiring.

But could the fault be somewhere else on the car’s electronics systems (lambda sensor, immobiliser....), and the ‘wire jiggle cure’ is only coincidental?

Advice welcome please. The car is the 2.0 petrol-engine RX4 model, manual gearbox, and it’s only just clocked up 100,000 miles.
 

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I had the same problem with my 02 2ltr scenic On a regualr basis it would refuse to start either hot or cold. We could either wait a few minutes (3 to 15) or just "Wiggle" the wire on the TDC and it would start. But we have not had this problem since I started to clean the TDC sensor on a regular basis. Using a thin piece of bamboo cane with a ball of cotton wool wrapped around and then taped to the end of the bamboo cane Then dip it in some cleaning fluid (I used a solvent based one) DO NOT DO THIS WHILE THE ENGINE IS HOT!! gently pushed into the space between the TDC and the engine block a few turns back and forth let it dry out for a few moments and the car should start perfectly first time!
NB. As the sensor is open to the under bonnet elements it will attract all kind of dirt, regular cleaning should keep it going.
Hope this works for you, let me know
 

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Is the connector on the TDC sensor black or blue?

There is a known problem with this connector and a modified sensor and wiring is available with a blue connector.

If your car has a black connector it has not received this modification.

Problems with this sensor often do not set a fault code but it can be tested with an oscilloscope or diagnostic equipment at the time of the fault. If your sensor has a black connector it might be worth having it replaced anyway, as it'll almost certainly cure this fault as well as giving you peace of mind.

I've replaced over 100 of these and never seen a problem with the blue connector.
 

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Discussion Starter · #4 ·
Many thanks, ‘Rivermersey’ and ‘Disgusted’

First, ‘our’ RX4’s TDC sensor – now (Renault-garage) replaced twice in 12 months! – is blue. I’m sure the sensor is OK – it wouldn’t work otherwise? - but not so sure about the wiring to/from it!

Next, the ‘old bamboo cane test’: not certain how one gets such a device down to the offending (and mostly invisible from above) part without dismantling the entire air intake/filter system and performing Houdini turns around the myriad of hoses and wires! Would an aerosol can of ‘neat’ pressurised air with a long nozzle be likely to work, eg by blasting away any dirt? Or eg WD40 if the engine’s cold? And how do I persuade Mrs M (5ft 2in!)to perform this task in a supermarket carpark?(!)

Third, the “3-minute wait”: Today, after a 10 minute drive to our local supermarket, and as I’d not left enough room when parking for Her Indoors to open the tailgate, I tried to restart the engine immediately after stopping it. For the first time in a week, the RX4 refused to re-start! “Leave it while we do the shopping” said Mrs M, wisely. 20 mins later..... the car started first time! Not a hot day down here today (only around 26C), but..... engine Heat affecting the Sensor-to-wiring loom?

The plot thickens. Perhaps I should get the garage to remove the TDC sensor and solder the connecting wires to it instead of relying on what I assume are flimsy push-fit male/female pins.... ?

Thanks again both.

:mechanic
 
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