Dodgy Starting Mk2

[Golf Loon]

Mk2 Digifant Aussie Car

Goes OK, but usually when hot it starts by coughing and spluttering and then runs ok.

Smells of fuel and doesnt run as well as it should. uses heaps of petrol too.
Cold start is not too bad.

Changed the fuel pump relay. Can someone with a digi Mk2 look at the vacuum lines from the throttlebody and tell me where they should go, this one has two hoses, one from each outlet, joined by a T and going to the FPR. Is this right?

[h100vw]

Bad water temp sensor MAtt.

Unless it runs better when stone cold then it might be the lambda probe

[tommymac]

if u show me a pic mate i can check mine

[Golf Loon]

How many water temp sensor matter Gav?

I changed the blu two pin one on the top of the water outlet, there is another underneath, which I thought was for the gauge only.

It does actually run better stone cold.

I was thinking Lambda probe, will hook it up to the VAG com and check tomorrow.

[86gti]

cold start injector running more than it should? do digi run a thermo time switch on the 5th inj?

[h100vw]

How many water temp sensor matter Gav?

I changed the blu two pin one on the top of the water outlet, there is another underneath, which I thought was for the gauge only.

It does actually run better stone cold.

I was thinking Lambda probe, will hook it up to the VAG com and check tomorrow.

Yeah the blue one for the ECU.

The good cold running points to the probe or wiring mate.

Not sure that the VAG-COm can do much for you. You can check the output of the probe with a voltmeter. Monitor the purple wire with respect to earth and you should see the voltage rise from 0 to 1 volt as the engine warms up. Once up to temp the meter will not be able to keep track of the voltage because it will constantly be changing. As it and the ECU alter the mixture. If you floor the throttle it'll go to a full rich state and then when you back off it'll drop to zero until the idle cuts in. This is because of the over-run cut off.

If it doesn't work as described above you need to check that the heater wires are ok as well as the earth and signal to the ECU.

I reckon it runs lumpy once warm because it has nothing to gauge the fuelling on so runs rich to avoid engine damage.

Gavin

[tommymac]

isv? not sure tho

[Golf Loon]

That sounds exactly like it Gavin, I can read the lambda output with my 1551 machine, but the symptons you describe are right on the money.

I`ll try it tomorrow and let you know how I go.

[h100vw]

I can read the lambda output with my 1551 machine,

Or not as the case may be ;0)

[Golf Loon]

Yeah the car starts great dead cold and worse as it gets hot.

However, I cant get the lambda out of the manifold.
We tried for ages today, but its up behind the engine near the firewall.
Its welded itself in there with the heat. I even tried a big spanner on the sensor and an engine crane connected to the spanner and it still didnt undo, just lifted the car!!

I`ve already cut the wires as the spanner wouldn`t go over the connector, so I have to change it now. Aaaargh

I`m thinking maybe just put another sensor in a more acessible part of the exhaust.

As for sensors, I have lots of Mk3 ones which have an extra grey wire. Can I use one of these if I omit this wire? There are 2 white wires, how do I know which connects to which?

[syncro]

It should run OK without the O2 sensor. I tried my syncro with it disconnected and it didn't make much difference. It is only a fine tuning adjustment.

[h100vw]

Yeah the car starts great dead cold and worse as it gets hot.

However, I cant get the lambda out of the manifold.
We tried for ages today, but its up behind the engine near the firewall.
Its welded itself in there with the heat. I even tried a big spanner on the sensor and an engine crane connected to the spanner and it still didnt undo, just lifted the car!!

I`ve already cut the wires as the spanner wouldn`t go over the connector, so I have to change it now. Aaaargh

I`m thinking maybe just put another sensor in a more acessible part of the exhaust.

As for sensors, I have lots of Mk3 ones which have an extra grey wire. Can I use one of these if I omit this wire? There are 2 white wires, how do I know which connects to which?

Get a mk3 manual and see what they are all connected to. The ECU will only need the earth and the signal connected to work but the probe may need power and a separate earth for the heater before the output is any good.

The heater is there so the probe gets to temp quicker, rather than relying on the exhaust gases alone.

I don't think you could get away with out having it connected, I have seen enough bad running G60s in my time to make the statement. They run the same with and without until up to operating temp.

Gavin

[Golf Loon]

The Mk2 sensor has 2 white wires and a black one.

The Mk3 has 2 white, a grey which I think is for heater and a black one.

Does it matter which whites I join together??

[h100vw]

I reckon the whites are for the heater, the grey is probably the earth for the signal and the black the signal. Like a light bulb, I don't think it matters which way round they go.

Gavin

[aussieg60]

I am sure the 2 white wires are 12v for the heater (it shouldnt matter which white gets the 12v as its just a resistor) and the grey should be GND. The black is the signal wire as Gav said. My motor was the same, switched on from cold ok, after heated up it run like crap because the 02 was not earthed. The 4 wire sensors need the grey wire grounded because the ground is crap through the exhaust system.