car wont start key light flashs once on dash.
 

hi all. im new to this group i think this could be my 1st post. i have a issue with me saxo vts. all ways starts on the button but i did some work on the car this week welding and painting. and now the car wont start. and i have a key symbol on the dash when i 1st turn the key. i havnt unpluged any thing on the car today only dissconnected the battery. any ideas how i can get it started. im guessin it imobilzer. i have a 3 plug ecu how do i over come this. thanks lee

an immobilised engine would have the key symbol on the dash flashing.

Normal condition is the light comes on steady, then goes off.

Does the engine turn over? Can you hear the fuel pump prime? The car can do both of these even when the ECU is immobilised. So if it dosn't turn over or you can't hear the fuel pump then you have another fault - either starter wiring or faulty fuel relay under the ECU.

car turns over fires once and then stops. i have fuel pressure at the rail and coil pack is sparking. i cant say ive noticed the key light on dash when starting maybe over looked it tho. i also have no codes saved in ecu. i drove the car in the garage and 1 hour later nothing. very strange.

Guess is you've burnt through a wire.

ive checked all wires all look ok i have found i have a weak spark on 12 and 4 and a strong spark on plug 3. no idea why. im guesing the welding has caused a issue. maybe coil pack or ecu issue. very strange. never seen this before.

The coil pack is driven directly by drivers in the ECU. the ECU's are very sensitive to static (this includes spikes from welding)

It's not an immobiliser issue if the engine starts.

How are you testing for spark? it's dual coil. So it's very rare to have a good spark on 1 cylinder and not the other three, they usually fail in pairs.

Where did you do welding on the car?

welding was on both front inner archs. os was fine no issue started when done ns. i have now fitted the ford coil pack upgrade spark is now spot on. fuels pressure is good at rail. but injectors only open for a split second and then dont open again. tested with injectors out. so i have a fuel issue. it looks like injector 3 is dry also. so maybe i have 1 injector down. im getting my muilt meter home from work 2moro and goin to check the wiring back to ecu and injector relay
after that il be looking for a 3 plug ecu if any 1 has one on here lol.

Ahh so you're actually getting a spark then. The ecu isn't immobilised then at least.

The flywheel sensor is the main trigger for the injectors and the spark. so if it's sparking correctly then the flywheel sensor is okay.

Not sure I can be of any more help. that's weird. I don't want to suggest that the ECU has died lol cos I've been there.

ive carried out wiring checks. i have 12v at injectors. so my guess is ecu is not earthing out to open injectors. so either im missing a input else were or i need a ecu. doin my head in lol.

Is the ECU bolted down? and are the earths clean and tight?

I ended up breaking my 16v for bits lol

ecu hasnt been bolted down for months didnt think that would cause a issue. need pin data for a 3 plug ecu before i check all the lives and earths in to ecu. ive only checked injection side back to the relay lives are all correct. just need to check back to ecu now. ive orderd a haynes maual so that should help with pin data. but my gut feelin in ecu issue. has any one on here got a unlocked 3 plug ecu for sale.

Nah I was just clutching at straws now :P the ECU doesn't need to be bolted down.

Be careful with the Haynes, I was just telling another forum member that it has mistakes in the wiring diagrams. the dash wiring being one of them - at the cluster. I'm not sure what else because I don't have it anymore.

Maybe find someone with access to auto data?

Apologies, posted in error.

i got auto data . no pin data for ecu on there tho. i cant get on to the sales pages on here. has any one got a ecu for sale on 3 plug.