6 replies to this topic

[Neilson]

I've reconnected my SPi after a rebuild and somethings not right. When I connect the battery up the main relay in the relay pack closes. The ignition switch is in the off position and is working fine.
This is sending a constant live feed to the coil which is overheating it.
Am I right in thinking the ECU normally earths the 'main relay' circuit when the ignition switch is turned on? I have taken the ECU apart and powdercoated the case. Does it sound like I have shorted something inside the ECU?
Or could it be something else? Any ideas appreciated.

[orcadian]

Hi,
It's possible that you did something to the ECU, but the very first thing that springs to mind is an earthing fault, allowing a 'false' earth being made through a relay coil. You've probably seen the same sort of thing when following another car while it's braking, and one of the indicators comes on dull - bad earth. Try checking that all of the earths you disturbed, to make sure they are making good electrical contact. If you have a multimeter, set it to OHMS and check between earth tags and the body bolts - it should read near enough zero ohms. Mine is MPI and has an earth block by the nearside inner wing in the engine bay - but SPI may have a different location.

[Neilson]

Hi,
It's possible that you did something to the ECU, but the very first thing that springs to mind is an earthing fault, allowing a 'false' earth being made through a relay coil. You've probably seen the same sort of thing when following another car while it's braking, and one of the indicators comes on dull - bad earth. Try checking that all of the earths you disturbed, to make sure they are making good electrical contact. If you have a multimeter, set it to OHMS and check between earth tags and the body bolts - it should read near enough zero ohms. Mine is MPI and has an earth block by the nearside inner wing in the engine bay - but SPI may have a different location.

But it seems to be earthing when it shouldn't be! So I wouldn't of thought it's a dodgy earth. The opposite in fact?

[Rented]

hi Neilson , are you in bournemouth itself or outskirts ? I live just outside blandford form - at our garage is diagnostic kit and 4 mechanics who can help if your local enough to the area - otherwise i can keep a look in the diary incase i am passing bournemouth sometime soon and take a look if you like .

[xrocketengineer]

I've reconnected my SPi after a rebuild and somethings not right. When I connect the battery up the main relay in the relay pack closes. The ignition switch is in the off position and is working fine.
This is sending a constant live feed to the coil which is overheating it.
Am I right in thinking the ECU normally earths the 'main relay' circuit when the ignition switch is turned on? I have taken the ECU apart and powdercoated the case. Does it sound like I have shorted something inside the ECU?
Or could it be something else? Any ideas appreciated.

Hi,
I had a problem with the main relay being active, see the link below. It turned out that is known failure mode of the ECU. However, I do not remember the HT coil overheating, but I might have missed that.

Hope that helps,

Ivan

http://www.theminifo...howtopic=119357

PS

You are correct, the HT coil would have power, I missed that.

Edited by xrocketengineer, 13 February 2010 - 04:50 PM.

[Neilson]

Thanks rented. I've sorted the problem now but I'm bound to get some more as I complete the re assembly! I'm in wimborne actually so just down the road from you.
The problem was I took the ECU apart and powder coated the case. When I put it back together I forgot to put a piece of insulation tape between the case and Triacs i think there called. Anyway it meant that some of the circuits were earthing through the case, inc the main relay circuit and coil as soon as the battery was connected.
It started up first time which was amazing. Seems to be idling at high revs at the moment but not sure until I get the tacho wired in.

[Blatherskite]

Thanks rented. I've sorted the problem now but I'm bound to get some more as I complete the re assembly! I'm in wimborne actually so just down the road from you.
The problem was I took the ECU apart and powder coated the case. When I put it back together I forgot to put a piece of insulation tape between the case and Triacs i think there called. Anyway it meant that some of the circuits were earthing through the case, inc the main relay circuit and coil as soon as the battery was connected.
It started up first time which was amazing. Seems to be idling at high revs at the moment but not sure until I get the tacho wired in.

Well found - had no idea about earthin g in the ECU.

Apparently, after disconnecting the ECU and reconnecting, it takes a while to relearn what it forgot abot the engine, so I guess it is likely to run a little wild for a while.