Car starts then cuts out immediately

[Gavin Waddell 18]

Ok I’ll try that then i have already replaced all the connectors in the plug with new JPT ones. 

 

I will make up two new fly leads for CTS and AFM and connect them straight to the battery and see what happens.

[Gavin Waddell 18]

I went to the car today made up 2 new fly leads for the AFM and CTS connectés them to the battery and ..........nothing. Will have another look tomorrow and measure with the multimeter to see what values I get or have changed. 

 I gone start maybe looking at the ignition coil side of things to see if I’m getting a trigger pulse. 

[PhilNW 44]

Presumably you mean the battery ground?

[Gavin Waddell 18]

Yeah sorry

[PhilNW 44]

Suggest you double check the resistance of your fly leads and original earths of the AFM and CTS connectors with the connectors and both terminals of the battery disconnected. The resistance of the fly leads should be less than 1 ohms.

[Gavin Waddell 18]

Went to check the resisitance of the grounds and they where identical for my fly leads and the original earths, between 0.50-0.60 ohms (multimeter  set at200ohms ).

[PhilNW 44]

Still got the 124 ohms on the AFM ground?

[Gavin Waddell 18]

I’m still working my way through this, the 134 ohms seems to be in all the grounds? Meaning I have a resistance some where. I’m going to make up a new   Cable from the gearbox to the battery’s and also from the ing/amp plate to the battery( i actually forgot to reconnect it whilst doing my testing, reckon it might influence something ?)

 

i found a really good site for checking and setting up the all the injection components http://www.dethomaso.fr/pages/DOCUMENTS_DE_REFERENCE-8085413.html

 

its all in french though ( luckily I’m fluent in french).

 Another thing I wanted to change the écu earth cable bin 1 and 13 but can’t get them out of the connector im assuming they are standard JT connectors ? Any one ever had trouble with these before .

 

will keep posting my progress

[PhilNW 44]

Think you have got to chase down the high resistance ground(s) before you do anything. There must be a common fault somewhere for that to happen.

 

What the resistance at both ends of the gearbox to body cable and the battery ground ?

 

Would not start to start replacing individual ecu ground wires/connectors (1 and 13) at this stage, at the end of the day the car runs when either the AFM or the temp sensor are disconnected.

 

The pins have a lug on them that prevents them pulling dropping out

 

https://www.vehiclewiringproducts.co.uk/c-1-home/c-60-terminals/c-72-non-insulated-terminals/c-206-terminals-to-fit-mouldings

 

you need a special tool something like this 

 

https://www.vehiclewiringproducts.co.uk/c-1-home/c-60-terminals/c-72-non-insulated-terminals/p-351-terminal-extraction-set

 

to get them out  

 

 

Edited September 17, 2020 by PhilNW

[Gavin Waddell 18]

I’ve got the tool. But I can’t get the connector out, I’ve been able to replace all the other loom connectors but the écu ones don’t want to budge!!!!!

[welshpug 1,661]

have you taken the rear cover off and the lock strip out?

[Gavin Waddell 18]

That will be why, took the rear cover of but didn’t see the lock strip got a picture?

[Gavin Waddell 18]

Locking strip found, new earth and connector crimped on.

[Gavin Waddell 18]

Locking strip found, new earth and connector crimped on.

[Gavin Waddell 18]

Little update I went to the car today with high hopes. I redid the wiring from the AFM plug to the écu connector, I chinches the earth wire on écu plug #5 and redid the connection where all the earths meet. I also made up a new ground strap from gearbox to battery. I made a new écu temp wire from plug to écu connector. After all that still nothing Car wouldn’t start, un plugged the AFM and vroom it’s starts FFS!.

 

then I had a thought what are the injectors actually doing , started the car with AFM unplugged and had a listen with a scene diver and I car hear them clicking which is normal.

 

i then plugged the AFM in place and tried to start the car and listened to the injectors and I could heat them clicking??

 

so here’s a thought when I unplug the AFM or CTS the engine goes into LIMP mode where it dumps a ton of fuel to compensate for not getting a return signal. 

Could it come from a dodgy fuel pump it is an AliExpress Jobbie not delevering enough fuel  pressure  When everything is plugged in and working normally. I mean I hear the injectors vlicking

 

 or am I barking up the wrong tree I’ve neatly made an entire new loom soon.

 

gavin 

[Tom Fenton 1,542]

You need to test fuel

pressure. Should be 3 bar

[Gavin Waddell 18]

Ok so update, following on from last weeks episode, we reckoned I say we because I go some advice from someone one here, thought that the fuel plump was not working properly(Ali express jobbie). So I whipped it out and put the old one in( standard Peugeot) and low and behold the bloody thing only started !!!!! I’m a happy man.

 

Goning to sound like an Oscars speech but thanks to everyone one on the forum for their advice. Telf for trying to teach me basic electrical checks. Damir for pointing me n the direction of the you tube videos which are very helpful.

PhilNW for his advice on the fuel

pump, and any one else thanks guys. I think without the help

and advice I got I would still be probing random things with a multimeter. It took two years but I learned a moult along the way.

 

iam going to change the fuel pump and redo the wiring loom and drive the bloody thing this spring.

 

thanks everyone, it’s good to have a forum where people give you a real answer and not just criticise.

 

Gavin

[PhilNW 44]

Well done Gavin, got there in the end, below is what I think was happening, 

 

The pump effectively runs at a fixed rate/pressure when running it does not vary in speed. Any excess fuel the engine does not need when running returns to the tank.

 

The ecu controls the amount required for each injection via an internal ecu calculation based on the AFM and temp inputs. I would guess there is a default value for the amount of fuel injected based on the normal expected fuel pressure (approx 45 psi) which allows the engine to run if there is no signal. If the ecu gets an input from the AFM for example it will override the default and will change the fuel injected to what it thinks is the correct amount again based on 45psi, with a low fuel pressure it is not enough to run.

 

Any thoughts anyone?

[DamirGTI 342]

Nice one !

 

You did much more than needed , but learned something new throughout the process of fault finding which will be useful skill for the future ..

 

Those china made fuel pumps seem really poorly made .. :

 

https://www.thesamba.com/vw/forum/viewtopic.php?p=8874567

 

.. i'd say maybe 1 out of 10 works (for how long god knows) , the rest are just "problematic" or seldom working .

Quality control is surely non existent .

 

 

D

 

 

 

[Telf 224 2 Cars]

Good news!

 

Glad you got there in the end.