Glow-in-the-dark: The Science of Persistence

hello

I have an Audi 80 TDI with the older 1Z engine (182 Nm). My engine is constantly overheating, no matter how warm it gets. I've already replaced the temperature sensor in the upper hose near the cylinder head, but I don't think it's related. Does anyone know where the other temperature sensor is located? (As far as I know, it has two temperature sensors). Or should I start by replacing the relay? What other potential causes could there be?

Thank you in advance.

christian

The relays and display are controlled by the engine control unit (ECU).

If you get a new relay, it will "display" the same way.

Are you sure it's actually glowing, or is it just the lamp in the dashboard that's turning on?

In the case of TDI engines, these are actually two different things.

m;

Hi 80 TDI,

Just plug a voltmeter into one of the spark plug connectors (and connect the other lead to ground) while the engine is running and warmed up.

If there's voltage applied and it's glowing, then you can continue troubleshooting, for example, by checking if the glow plug relay is being activated or not.

If nothing is on it, it won't light up!

hello

I know that it really glows for as long as the ignition is on. I don't think it glows when the engine is running, but I need to check that. Once it's properly warm, you can remove the relay, but it shouldn't be a permanent solution.

best regards, christian

Really warm???

The 202Nm 1Z model no longer glows from 5 degrees Celsius onwards.

And even then, it starts.

My ex's 1.7 SDI (AKU) immediately flooded after just one night at -15 degrees Celsius, and it started running immediately .

My PD TDI also started too. The 1Z also started after about 1.5 weeks of being parked outside (due to an accident). I'm not sure why it was so difficult to start in the winter, though.

Best regards, WarLord.

hello

Even today, with almost 20°C outside, it's glowing. When the engine is running, it glows for a bit, then stops. If I then turn off the engine when it's warmed up and turn the ignition back on, it starts glowing again. What do you think I should check first?

christian

Have you checked the resistance of the coolant temperature sensor? Use a multimeter and compare the resistance value to the specifications in a repair manual like 'Jetzt mach ichs mir selber' or a similar DIY guide.

I went to the workshop and wanted to find out which temperature sensor is responsible for the glow plug system. However, the parts specialist couldn't give me an answer, even though he had spoken to people from the workshop. Now, I probably have to buy a "how-to" guide to figure it out myself. I'm just worried that it might only cover the subsequent engine model (also 1Z). I'll get back to you once I've found the correct sensor.

best regards, christian

@christian

The glow plug control depends on the coolant temperature. The sensor can, of course, be read out using a diagnostic tool and should then provide plausible values.
The combination instrument has its own temperature sensor, so its display is not the determining factor for the EDC (Electronic Dampening Control) system.

CU Gremlin.

You're welcome, gremlin.

That's probably the best way to go if I have the value read out. Unfortunately, electricity isn't really my area of expertise, but the people at the workshop couldn't help me either.

best regards, christian