ECU relay box

mjb · Post by **mjb** » Mon Jun 04, 2007 10:21 pm

Anyone know what the relay block (the lump in the ECU box with a big connector, next to the ECU) actually controls? The connector clips on mine have broken and it managed to vibrate its way loose earlier causing an interesting stall. I say interesting because trying to re-start the engine failed, but the starter caused noticeably more vibration in the car than if I tried to start it with the immobiliser active!

If anyone has a duff wiring loom they're about to throw out, can you hack off the little blue relay connector (leave about 2" of wires) and sell it me?

Post by **Welly** » Tue Jun 05, 2007 9:01 am

When you stalled m - I bet you thought ''oh no - CAMBELT''

mjb · Post by **mjb** » Tue Jun 05, 2007 9:09 am

Welton wrote:When you stalled m - I bet you thought ''oh no - CAMBELT''

Actually no... it was a gentle stall from idle, like switching the engine off only slightly slower. My first thought was actually blaming it on my uneven idle being a bit too uneven!

jameslxdt · Post by **jameslxdt** » Tue Jun 05, 2007 6:58 pm

its the engine management double relay, it controls the injectors and ignition coils, the ecu sends out a low current signal to the relay, which in turn fires one of the coils and all of the injectors ( as the MP5.2 L3 runs wasted spark and simletaneous injection) and the other side triggers the other coil

mjb · Post by **mjb** » Tue Jun 05, 2007 8:36 pm

I'm intrigued as to why the car noticeably shook more with it unplugged. If there's no injector activity then shouldn't the only difference between the relay box being unplugged and the immobiliser being active be the fuel pump?

jameslxdt · Post by **jameslxdt** » Tue Jun 05, 2007 8:59 pm

ah yes i forgot to mention it also controls the fuel pump, so if it unplugs or starts to unplug it will shudder to a halt, as you will have intermittent low fuel pressure, odd injector timing and the ignition timing will also be out or have a weak spark