Earthing the ECU - UPDATE Post #11 Intermittent Starting

[Ibiza125]

Basically my car has been intermittently not starting. It goes through spells where it starts everytime, then out of the blue it won't start. When it did this one time I kept trying to start it and eventually it went after leaving it for about 5 minutes.

Now I put in vag-com, and what happened was it wouldn't connect with the ignition on, but would connect with it off and even without the key in the car. This led me to think it was something ECU related. I have the codes that were on the car saved but they are in the car which is at work.

So I had a look at the ECU and saw the earth cable wasn't connected, so I put that onto the wiper motor bolt and that seemed to work ok for a while. But now it won't start again.

So yesterday I put the earth cable on the proper earthing point but behind the ECU cradle, should it be infront to get the best earth?

Basically I'm asking what is the proper way I can earth it?

 

[Chez]

my car did this last year, took 6 months to eventually fix :-(

i had the same prob, no communications with ignition on but fine with it off, turned out to be a melted resistor and cable in the instrument cluster circuit board which stopped communication between the ecu and cluster.

 

[CupraElliott]

There's noting really wrong with the original earths, along as it's clean and the cable itself is fine I can't see how that's the problem?

 

[Ibiza125]

I had these fault codes come up when I first checked it.

5 Faults Found:
18057 - Powertrain Data Bus: Missing Message from ABS Controller
        P1649 - 35-10 - - - Intermittent
16487 - Shareware Version. To Decode all DTCs
        P0103 - 35-10 - Please Register/Activate - Intermittent
18010 - Powertrain Data Bus: Missing Message from ABS Controller
        P1602 - 35-10 - Please Register/Activate - Intermittent
18011 - Internal Control Module Malfunction
        P1603 - 35-10 - Please Register/Activate - Intermittent
18084 - EPC Warning Lamp (K132) Circuit: Electrical Malfunction
        P1676 - 35-10 - Please Register/Activate - Intermittent

The only ones I've seen coming back are these:

2 Faults Found:
18057 - Powertrain Data Bus: Missing Message from ABS Controller
        P1649 - 35-00 - -
18010 - Power Supply B+ Terminal 30: Voltage too Low
        P1602 - 35-00 - Please Register/Activate

18057 is because I have my ABS disconnected due to my ABS rings being knackered. What are the others about?

 

[olvie]

hmm weird one could it not be crank shaft sensor??? sometimes those play up.....

 

[Ibiza125]

I could change that out and see. Want to make sure it could be that though as they are quite expensive :O

I am also going to try and new 167 relay see if that helps.

 

[olvie]

how much for the crank shaft sensor???
i used to have the same problem with my old mk2 gti 16v cupra and i changed the crack shaft sensor and it was fine....

 

[Ibiza125]

how much for the crank shaft sensor???
i used to have the same problem with my old mk2 gti 16v cupra and i changed the crack shaft sensor and it was fine....

£80 for a Bosch one from eurocarparts. Is it easy to change over?

 

[olvie]

hmm thats not too bad
i dunno mate mine was done under warrenty...... but they only charged an hours labour so doubt it is

 

[Ibiza125]

UPDATE:

I have tried a few things and noticed everytime I disconnect the battery to clear the ECU fault codes etc, it starts up first time after I reconnect it. I then go to turn it off to see if it will start after and it doesn't. I am charging my laptop to see what vag com comes up with after doing it this way.

Does this point towards anything, or remove anything else from being the problem?

 

[Ibiza125]

Right so not fault codes came up bar the usual ABS and Battery ones (for ABS being disconnected and me disconnecting the battery.

The full description of what happens is: I can start the car, I then turn the car off, sometimes (not always) the car will not start back up, I can also not connect vag-com to the car while the car won't start, I then disconnect the battery and reconnect it (not having to wait for fault codes to clear) and it will connect to vag-com and fire back up.

Any thoughts?

 

[Chez]

sticky throttle body flap?, maybe resetting with battery off then on?

this may be a stab in the dark, but it could need cleaned (or im talking rubbish) .

or check the ecu plugs and multi pin leads for any signs of corrosion causing poor contact.

 

[Ravey_Cupra]

ECU out, take cover off and put in an airing cupboard for a day or 2, reseal when putting back together and put back in car.

I was having the same issue, I also put electrical contact cleaner and promoter on the plugs when putting it back together, not failed me up until now.

 

[Ibiza125]

ECU out, take cover off and put in an airing cupboard for a day or 2, reseal when putting back together and put back in car.

I was having the same issue, I also put electrical contact cleaner and promoter on the plugs when putting it back together, not failed me up until now.

When you say the same happened to you do you mean that it randomly wouldn't start?

 

[jaypee]

When you try to restart the car does it crank but doesn't catch, or do you not even get the starter motor turning?

 

[Ravey_Cupra]

When you say the same happened to you do you mean that it randomly wouldn't start?

Yep, would be fine in a morning to get to work, fine leaving work but if you stopped and turned engine off it wouldnt fire up again.

Tested this over and over again on my driveway, fire up 1st time then wouldnt do afterwards unless you disconnected battery and unplugged ECU.

Since it went in the airing cupboard Ive had no issues.

 

[Ibiza125]

When you try to restart the car does it crank but doesn't catch, or do you not even get the starter motor turning?

It turns over well yes, but doesn't catch. Sometimes if I try enough times on and off it will go eventually. But this varies time to time from 5 goes, to not starting what so ever.

Yep, would be fine in a morning to get to work, fine leaving work but if you stopped and turned engine off it wouldnt fire up again.

Tested this over and over again on my driveway, fire up 1st time then wouldnt do afterwards unless you disconnected battery and unplugged ECU.

Since it went in the airing cupboard Ive had no issues.

Sounds good to me! If it's a simple fix like that then that would be fine

 

[charnandy]

Did you ever get this fixed? Mine's started having similar issues. Did the ECU trick work?

 

[stuibaby]

I once had error messages coming up on VAGCOM referring to the ECU - so i looked at ECU and it looked a little damp.

Aired mine out and when it was totally dry i resealed it and made a little cover (Not air tight!)

Never had problem with it again - TOUCH WOOD!

The ECU isn't very well protected from the elements - a Home made cover is a good way to try and defend the ever ageing bit of Tech.

 

[Prebs]

I stopped for petrol after 6 hours of driving going to a annual vwaudi gathering.

When I got back in the car it wouldnt start, you could hear the starter crancing the engine but no GO, I then tried to hook up with vagcom (I never leave without!) but couldnt get any contact with controller. Tried do disconnect battery for 15 min but same result.

Then I removed the ecu for 15 min and put it back in. Then it all started. Checked for fault codes by scanning with vagcom and it came up with a "anti theft code" withc I cant remeber code on as its on my laptop.

The same happened the next day so ECU out again! This is about a month ago but havent happended since but I alway carrie basic tools in the boot in fear of similar to happened.

My ECU has just bin remapped so I guess it could be due to some internal work in the ECU!