Have i Fried my ECU?

[cam_ra40]

Before i start, my car is an Aus spec AE92 with an AFM 4AGZE.

I installed an A/F ratio kit from jaycar a few days ago, it was only going to be there temporarily. Anyway, to cut a long story short, I left the Oxygen sensor wire off and it was on the interior, this morning i started my car and the oxygen sensor wire happened to touch the steering column and sparked (i didn't realise the thing was live!). The car then stalled & blew the EFI-Heater fuse under the bonnet, i replaced the fuse with another 15A fuse (reccomended type) and it just keeps blowing them, the car turns over but won't start.

Any suggestions? every other fuse seems to be good, there is a couple of chunky things in the underbonnet fuse box that look like relays and are listed as EFI-Heater as well, could i have blown one of them?

How can i test if it is the ECU or not? anyone got an AFM 4AGZE ECU for sale?

[Draven]

follow the oxy sensor wire back and look for any charring/smouldering on the plastic - you could have welded the wire to somewhere else, and it is now permemantly earthed out. You're pretty unlikely to blow the ecu as easily as that - that's what the fuses are for

The car won't start with the efi fuse blown, so until you fix that problem I wouldn't be worried about it not starting.

[cam_ra40]

Sorry i didn't word that right. The oxy sensor is just setup normal with no A/F gauge anymore. I still have the positive and negative connected to the A/F gauge and the Oxy sensor wire dangling on the interior (stupid i know) turns on the oxy sensor wire was live and bumped the steering column.

I'm going to take out the ecu and see if the efi fuse still blows, this should rule out or confirm that it is the ECU shouldn't it?

if it isn't the ecu where should i start looking for a short?

Thansk Heaps

[NeoNasty]

yes, if you remove the Ecu completly and it still blows fuses, then your problem is elsewhere.

Look in the engine bay for physically damaged wiring, it could be touching the chassis, as said above.

Pay special attention to where the wires go through the firewall.

good luck buddy, I hate shorts! Hope you find it quick

EDIT: If you remove thje ECu and it stops blowing fuses, taek the ECU to someone who knows lots about them, or is pretty cluey. If your lucky it may just be some protection diodes have shat them selves.
If the ecu is blowing the fuses, open it up, Look for damaged components. DONT go running your hands all over stuff, like sensitive ICs! Have a smell of it too. You can usually smell something has burnt.

[oldcorollas]

O2 sensors produce voltage.

the sense wire should not have voltage on it

is the jaycar kit still there?

pull it out...

then work out why there is power on the O2 sense wire....

it's not the O2 heater power wire is it? (12v)
got them mixed up?

[sideshow]

y would u use that kit anyway

most those cheap air fuel meters are very innaccurate and only work at light throttle

[The Witzl]

cam - i answered all this over at twincam.org... i hope all works out ok.

[cam_ra40]

oldcorollas: The ae92s have a single wire oxy sensor with no heater, the kit was made exactly as it was written in the instruction manual so i'm not sure what it was a live wire, all i know is that it was certainly live! the O2 metre is completely removed now.

Witzl, thanks for the reply on twincam! i'm about to go and start work on it now, i'll let you know how i go with it.

[cam_ra40]

Problem solved

I unplugged the ECU and the fuse still blew. Then i thought shit, where do i start looking to find the short circuit. Turns out that there was a spade connection from the alarm with a little bit of metal showing that had welded its self to the dash support.

Thanks heaps for the help guys!

[Grega]

good find!

[cambelt]

Thers nothing wrong with the jaycar mixture kit as long as its callibrated from a known acurate meter, i fit the simple jaycar mixture kit to all my cars on lpg just so you can tell if the lpg goes 2 lean or rich
Dave