Warm start problem - Renault Megane 1.6e

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Tue 2 Jan 2007 13:18
Warm start problem - Renault Megane 1.6e - nin
Renault Megane 1.6e Sport (R reg)

The car starts and runs normally until it warms up when the engine cuts out and would not start until it cools down. Clicking sounds can be heard from the fuel pump relay and the injectors.

The longer story: Some time ago my sister?s car suddenly started to misfire. AA called and towed it home. Local independent garage replaced coils and the car seemed to work for a week. Then suddenly it started the "coughs" again but could run for several miles to home. We took it for a short test run when it stalled. The garage towed it in again and had been looking at it for a week but could not fix it and gave up. They claim that unlike during the first visit the diagnostic tool did not show any error codes. They also tried to run it with fuel relay bypassed but it did not make any difference. Suggested to go to a Renault garage but the nearest is 15 miles away and my experience with them is that they are expensive and not very reliable.

Has anybody experienced similar problems? Is there anything that can be checked or fixed without special testers and diagnostic tools?

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Tue 2 Jan 2007 13:48
Warm start problem - Renault Megane 1.6e - DP
Are these equipped with HT leads, or are they individual coils? Can you get a strobe or an HT Tester on to check for a spark? I've had ignition coil failure on two cars and on both it happened only when the engine was hot.

Cheers
DP
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Tue 2 Jan 2007 19:58
Warm start problem - Renault Megane 1.6e - nin
I assume if this was the problem it should have been fixed when the garage replaced both ignition coils.

After the second breakdown we called AA again and the guy said the sparks were OK. Later the garage tested the sparks again and did not mention any problems. To be sure, I will try to find HT tester and re-check.
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Tue 2 Jan 2007 19:22
Warm start problem - Renault Megane 1.6e - Screwloose
nin

With any temperature-related starting problem on a Renault, I always think of the crank position sensor [TDC sensor] first. They don't always leave codes when they fail.
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Tue 2 Jan 2007 22:11
Warm start problem - Renault Megane 1.6e - nin

Thank you for the tip. Is there any way to test the crankshaft speed position sensor with multimeter? Renault quoted around £50 for the part and it will be good to know, if possible, if the sensor is faulty before going for a new one.

Is it possible that bad earth can cause similar problems?
Bad earth points seem to be quite common issue with these cars (three days ago I had to fix bad earth of the rear light panel in my car which is the same model and age; see also car-by-car breakdown on this site). I recall the garage mentioning that at some point during a "cough" even the plugged in test unit lost power. I assume one possible explanation for such "blackout" could be an unreliable earth point of the ECU.
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Tue 2 Jan 2007 22:36
Warm start problem - Renault Megane 1.6e - elekie&a/c doctor
Clicking sounds from fuel pump relay and injectors could indicate a poor earth connection for the fuel injection control unit.The ground earth points are usually on the front of the engine block or at the rear of the engine below inlet manifold.Another possibility is poor connections to the efi control unit multiplug , situated behind o/s headlight by inner wing area.
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Tue 2 Jan 2007 22:43
Warm start problem - Renault Megane 1.6e - Screwloose
nin

The crank sensor should show a resistance of around 200 ohms across it's two [disconnected] terminals. An oscilloscope is the preferred method of testing; but they're not widely available. If you can test it when it's not starting; then resistance may well be good enough.

Bad earths/bad wires/bad connexions are very possible; but it's the temperature component of the symptoms that suggests something that gets hot is at the root of the problem. This is a very common fault on all Renaults.

Some Renault engines break their engine management earth wires where they connect onto a bolted terminal at either the inlet manifold area or near the alternator. Given the scanner incident; worth a check. If not; maybe a secondhand crank sensor from a breakers for a quick test?
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Wed 3 Jan 2007 12:53
Warm start problem - Renault Megane 1.6e - nin
elekie&a/c doctor , Screwloose

Thank you for the advice and detailed descriptions.
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Sun 14 Jan 2007 08:29
Warm start problem - Renault Megane 1.6e - nin
We called local mobile electrician/mechanic who quickly found the offender. As elekie&a/c doctor suggested it was bad ECU connection: good cleaning of both the plug and the socket had fixed it.



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