clio won't fire

annie · Unread post by **annie** » 02 May 2005, 23:11

Hi I have a Clio that refuses to start, it turns over fine, has fuel compression but no spark, I have eliminated the coil from the problem but the coil is not getting the full 12v ( it seems to only be getting 2v feeding into it) I don't want to got to the expense of replacing thru ecu can anyone suggest any other cheeks I can make?

JamesQB · Unread post by **JamesQB** » 03 May 2005, 16:00

The 12V supply to the coil is switched (by the TDC sensor on the flywheel) in order to produce a spark, which is created when the 12V disappears and the EMF field is has produced collapses (known as flyback), so how are you measuring it? The 2V DC may be an average the meter is showing, or simply the highest figure it has time to climb to before the 12V disappears and then reappears again, unless it's too early in the morning and I've missed something obvious here...
Have you ascertained there is no spark by removing a spark plug, connecting it to its HT lead, grounding the outer of the plug and then getting someone to crank the engine whilst you look at the plug? No juicy blue spark across the electrodes of the plug?
Might be worth removing the TDC sensor and cleaning any swarth and filth from it, in case it isn't picking up any signals.
Before condemning the ECU, if your reading of 2V across the coil is correct, then it is possible that the coil has a short and is bringing the voltage down. Is the coil getting very hot?

bwellard · Unread post by **bwellard** » 03 May 2005, 16:46

I had a similar problem with my Laguna. It turned out to be the rotor arm needed replacing. Spark to the centre of the dizzy, but nothing to the spark plugs. Very easy to diagnose (JamesQB has given instructions!) and very cheap to fix.

JamesQB · Unread post by **JamesQB** » 03 May 2005, 23:31

Of course, that's a likely culprit! Said it was too early in the morning...

You can confirm such a problem by disconnecting the HT lead from the distributor (so it's coming directly from the coil) and, using a screwdriver or similar pushed inside it, placing the screwdriver ~0.5cm from chassis ground and seeing if you have a torrent of sparks jumping to ground when the engine is cranked.