diesel warm start problems

[Doctle Odd]

If you want to fool the ECU into thinking the engine is at around 20°c, something around 3kΩ

Thank you kind Sir

[Doctle Odd]

If you want to fool the ECU into thinking the engine is at around 20°c, something around 3kΩ

Hi Crasher

Before I blow something up can you tell me if this is correct?

30 Wire to CTS
87 Wire to ECU
87a Wire to ECU with resistor inline
86 Starter trigger wire
85 Earth

I been messing with this since you sent me the info but I'm sure I'm doing something bass ackwards

Thanks

[Crasher]

I have a diagram I made somewhere, can't find it. Not sure you have the resistor bit clear though. What will happen is with the starter NOT running, the signal from the CTS just runs straight through the relay via 30 and 87a. You can visualise this with a multimeter on continuity to show a circuit across 30 and 87a. You take a line from the red/black to the starter to 86 so when the starter is operated, 30 jumps across to 87 so a resistor wire connected to earth on this terminal is what you need but a tiny resistor soldered to the 87 pin across to the 85 earth pin will do the same thing and give the ECU a 3kΩ signal just whilst the starter is operating. The change over between resistances is so quick the ECU does not appear to ever see it as a fault.

[Doctle Odd]

I have a diagram I made somewhere, can't find it. Not sure you have the resistor bit clear though. What will happen is with the starter NOT running, the signal from the CTS just runs straight through the relay via 30 and 87a. You can visualise this with a multimeter on continuity to show a circuit across 30 and 87a. You take a line from the red/black to the starter to 86 so when the starter is operated, 30 jumps across to 87 so a resistor wire connected to earth on this terminal is what you need but a tiny resistor soldered to the 87 pin across to the 85 earth pin will do the same thing and give the ECU a 3kΩ signal just whilst the starter is operating. The change over between resistances is so quick the ECU does not appear to ever see it as a fault.

Thank you Crasher, makes sense. I was thinking that I should have the resistor soldered to another piece of wire that connected from 87 to 87a. I'll just go out to the shed and burn myself a little more.

[Crasher]

You aren't a real man until you have picked up a soldering iron at the wrong end and momentarily thought "what is that strange bubbling sensation in my finger tips.........aaarrrrrgghhh!"

[Doctle Odd]

I managed to cut my fingers doing it too

[Crasher]

Yes, but did it work? Was there are puff of smoke from the wires or the tailpipe?

[Doctle Odd]

Yes the setup seems to work fine, I was using space connectors, sidelight bulbs etc to test it. Spade connectors are too messy looking so I'm waiting until I get a proper harness and more resistors before I try it on the car. I'm currently using a push to break switch but the car revs like the fuel cut off is goosed. You're an extremely clever fellow to have came up with this and are deserving of much praise and a damn fine Beaujolais

[Doctle Odd]

Yes, but did it work? Was there are puff of smoke from the wires or the tailpipe?

Crasher you're a genius! The car starts soon as the key is turned. Many thanks

[Doctle Odd]

Octavia warm start fix - YouTube