@gills thread is brilliant and like you, and pointed me towards the whole block heater thing as my commute is fairly short. This is bad, but what's worse is that within 1/4 mile I hit one of the steepest hills in Sussex (up, not down). Always makes me cringe, the thought of a stone cold engine having to pull a car up that hill, however sympathetically I try to treat it. We're lucky to have @Joga 's expertise on hand in this regard
The coolant sensor thing reminded me of something similar I had with mine. I wrote it up on here at the time. It appears there are two variants of the 4-wire VAG coolant temp. sensor. One has chunkier terminals but is otherwise the same. I replaced mine with a new one with thicker terminals and it immediately cured the problems and has been good since (a couple of years). The symptoms were that sometimes the engine was difficult to restart from warm-ish. And sometimes the dashboard engine temperature gauge would read garbage (low or no reading, sometimes after initially showing a normal reading). These problems were getting gradually more frequent. I didn't realise at first that the two symptoms could be related, until I found out the temperature sensor has separate channels for ECU and the dashboard. It was easy to rule out the thermostat by measuring the coolant temperature when the dashboad gauge was reading low when it shouldn't. I used my cheap Hilka multimeter for this - it comes with a thermocouple. The coolant was invariably at 80+ degC. I then tried tugging at temp. sensor wires and this would restore normal service after engine restart. So I looked for a replacement 4-wire temp. sensor, there were plenty on eBay with pictures all claiming to be compatible. That's when I noticed that some seemed to have thicker terminals. I ordered one with the thicker terminals and when it arrived I could see the terminals were ineed much chunkier than in the one I was replacing, which by the way had been fitted originally by Audi Watford.The latest on the engine coolant temperature saga:
- They have successfully fixed an issue they found which was the cooling fan was running all the time - this was found to be a faulty sensor.
- They are continuing to investigate why the gauge is reading 65-ish even when VCDS says the engine is at say 82 degrees - Looks like, incredibly, that BOTH the new genuine VAG thermostat AND the coolant sensor I had replaced were both faulty - that will teach me for asking DS Motorsport to replace components that were working as they should previously! Lesson learned.
Check starter motor earth behind n/s head lamp. I'd had similar spurious ABS and sometimes power steering lights for months that would always clear up after engine restart. If allowed to deteriorate this can eventually lead to catastrophic failure - ignition, battery charging and starting problems. Worth investigating as in my case cleaning this up made the car start again and got rid of a bunch of intermittent nuisances like the spurious warning lights, reduced performance, intermittent remote central locking problems etc.When I jumped in for "my go" just now, I fired it up and the orange ABS + one other warning lamp (the orange one with the book circled by an arrow) stayed lit, followed a few seconds after by the bong of death and both a red exclamation mark and what looked like the brake symbol flashing up in the middle of the dash, which was scary! However normal service was resumed by the good old "turn it off / on again". Anything to be worried about?
That's not South Harting is it? I also live at the foot of the downs, so have to climb within 1/2mile of leaving home. Modern turbo engines have such a big mid-range that they can do so without exceeding 3000rpm, not sure about older N/A cars!
I found that the car would do 60mpg at 60mph in sixth and on the flat according to the DIS, with low 50s at 70-75. This seemed subjectively to improve a little on the return journey having brimmed the tank with Shell V-Power (including “burping” the tank using the advice I’d read on here). I still think the car should be doing slightly better than this however, I would be interested in opinions on this?
My own A2 will also do this, but I never allow it to. Even if the VGT turbo in the TDI90 allows enough torque to be developed and the engine seems comfortable, low-rev, high-load scenarios are terrible for the engine and gearbox bearings, and are thought to be a major contributor to oil-pump-mechanism wear. As such, the moment that I go below 60mph, I change down to 5th, even if that increases fuel consumption slightly. Long term, I believe this to be the lesser evil.Usefully, I found that on the 50mph section of the M4 the car was perfectly happy in sixth at 1500 RPM