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Model specific boards => Golf mk2 => Topic started by: mikemk4gti on 01 May 2012, 18:29

Title: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 18:29
Had a few moments spare so thought I would check over my earths on the gearbox and pos connection on the starter. I had the battery disconnected for about 20 mins.
Put it all back together, and now it won't start. The fuel pump is staying on constantly and it has filled the cylinders with petrol. I've took the fuel pump fuse out and spark plugs. I'm getting a spark ok. Have I wrecked the ecu somehow?
It's a 8v digi2 btw.
Title: Re: Help! Car won't start :(
Post by: tomp on 01 May 2012, 19:46
Yep sounds like the ecu is blown, same symptons as when I blew one once on an 8v

You will have to change the ECU and do an oil and filter change as the petrol will seem into the oil....
Title: Re: Help! Car won't start :(
Post by: clipperjay on 01 May 2012, 19:49
Checked your relay?
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 19:50
Oil and filters not a problem. But don't want to change the ecu until I know whats caused it incase it happens againn as soon as I plug a new one in (which I don't have :( )
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 19:51
Checked your relay?
Fuel pump relay? Surely that wouldn't allow it to bypass the injectors if they were closed?
Title: Re: Help! Car won't start :(
Post by: clipperjay on 01 May 2012, 19:53
Checked your relay?
Fuel pump relay? Surely that wouldn't allow it to bypass the injectors if they were closed?
Or stuck open?
Trying simple things for you!
Title: Re: Help! Car won't start :(
Post by: tomp on 01 May 2012, 19:55
I'd put money on it being the ECU, I did it when I was changing a gearbox, cylinders filled with petrol the same, bought one on ebay for about a fiver, problem solved...

Where in North Wales are you?
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 19:56
Ok, it's worth a try as I've got a spare one here, thanks.
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 19:57
I'd put money on it being the ECU, I did it when I was changing a gearbox, cylinders filled with petrol the same, bought one on ebay for about a fiver, problem solved...

Where in North Wales are you?
Colwyn bay
Title: Re: Help! Car won't start :(
Post by: tomp on 01 May 2012, 20:01
Don't forget to connect the positive first when reconnecting the battery...

Colwyn Bay is a bit far, could have lent you an ECU out of an 8v that I have here, pretty sure there is a guy on ebay who breaks mk2's in Colwyn Bay though
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 20:03
Ha ha, that's me that's breaking one on eBay, but not got an ecu.
Where are you?
Title: Re: Help! Car won't start :(
Post by: tomp on 01 May 2012, 20:08
Ha ha, that's me that's breaking one on eBay, but not got an ecu.
Where are you?

Oh right, no use there then!
Title: Re: Help! Car won't start :(
Post by: bodga on 01 May 2012, 21:09
Thought i recognised that golf in your sig mike. I'm the bloke who brought the bonnet of your dad the wk end.
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 01 May 2012, 21:17
It was running fine back then, only packed up today :(
Title: Re: Help! Car won't start :(
Post by: mk2bal on 01 May 2012, 22:19
Not witnessed it myself, but have heard of it a few times now. It seems having the gearbox earth removed causes starter return currents to flow through the ecu killing it. Always ensure all earths are in place before connecting battery/ new ecu. Also I think you want to connect earth before pos, as you ensure a return path which some components require
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 02 May 2012, 15:40
Ordered a replacement ecu now, hopefully it will be here tomorrow.
I've fitted a new earth from the battery to the gearbox. Is there anything else I should do or check to prevent it happening again?
Title: Re: Help! Car won't start :(
Post by: clipperjay on 02 May 2012, 16:06
Do you have a braided one from the ECU to the bonnet?
Plus we tend to double the negative lead to a gearbox bolt.
Title: Re: Help! Car won't start :(
Post by: tomp on 02 May 2012, 18:36
Not witnessed it myself, but have heard of it a few times now. It seems having the gearbox earth removed causes starter return currents to flow through the ecu killing it. Always ensure all earths are in place before connecting battery/ new ecu. Also I think you want to connect earth before pos, as you ensure a return path which some components require

I'm sure its positive first when reconnecting a battery, and positive last when disconnecting.... 
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 03 May 2012, 12:25
It's fixed, the replacement ecu turned up this morning.
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 03 May 2012, 12:27
Do you have a braided one from the ECU to the bonnet?
Plus we tend to double the negative lead to a gearbox bolt.

No there's no earth on the ecu at all? Should there be?
I added another to the coil as I had a spare from another mk2 I'm breaking.
Title: Re: Help! Car won't start :(
Post by: clipperjay on 03 May 2012, 13:06
TBF the one on the bonnet hook is more of a RF signal supressor, but Its still earths out, its on the scuttle pannel on the left facing the car. I don't have a picture, but find any bolts near the bulk head and then bolt it onto the exsiting bonnet hook bolt. This one is usually flat and braided. I've always though as its close to the ECU mounting plates it must help if static feed back does come around that side of the bulkhead?
The main one which stops the loopback of static that can do damage if not working, is the one from your earth cable to gear box! Hence doubling it will act as back up if one is corroded and not making good earth contact!
I just tend to find continuity test on all cables if its not a clear bleep it needs cleaning or replacing!
 
Title: Re: Help! Car won't start :(
Post by: mikemk4gti on 03 May 2012, 21:51
Ok thanks, just checked on the 88 mk2 I'm breaking and it's got one on the bonnet but on the n/s
Title: Re: Help! Car won't start :(
Post by: clipperjay on 04 May 2012, 09:28
Yeah you can have either side earths are your best friend!