LCR temp drop + loss of power in waves

[mph]

Not sure if these issues are related, but thought I'd ask...

So on a long motorway drive last week I noticed the temperature gauge on the dash dropped from 90 down to 60 and then hovered around 75 before returning to 90. It did this a couple of times. Obviously the engine wasn't cold, so could this be a sensor issue?

Also on the same drive, when I accelerated on the motorway, the power would surge and then drop, then surge, then drop, then surge, etc... like it came in waves. Now when I've had loss of power before, it's usually been a coil pack gone, but this time the car drives normally around town, but this only seems to manifest when hard accelerating on a long road such as the motorway.

Could the two be related?

 

[SlashProm]

first thought would be coolant temp sensor on the coolant flange bolted to the head, passenger side. Apparently there's a green top sensor upgrade as it's a common fault on these cars. It gives calculations for the ecu with relation to fuelling and ignition timing, as well as other factors. Can you get it plugged in anywhere?

 

[Prau187]

Could be your thermostat too get that replaced I had the same problem and I changed the thermostat and it was fine

Sent from my SM-N960F using Tapatalk

 

[mty12345]

Not sure if these issues are related, but thought I'd ask...

So on a long motorway drive last week I noticed the temperature gauge on the dash dropped from 90 down to 60 and then hovered around 75 before returning to 90. It did this a couple of times. Obviously the engine wasn't cold, so could this be a sensor issue?

Also on the same drive, when I accelerated on the motorway, the power would surge and then drop, then surge, then drop, then surge, etc... like it came in waves. Now when I've had loss of power before, it's usually been a coil pack gone, but this time the car drives normally around town, but this only seems to manifest when hard accelerating on a long road such as the motorway.

Could the two be related?

Hi mate, i don't think the 2 are related tbh...For the surging issue, i'd check all your boost and PCV pipework for leaks, and also scan for fault codes, preferably with VCDS.
IMO the second issue is definitely your thermostat. When travelling at motorway speeds in relatively cold weather, the airflow is so high and cold that the thermostat actually needs close to keep the engine warm enough (around 90C). When they get stuck in the open position you get the exact symptoms you describe along with taking more than 4-5 mins to warm up in the morning. It shouldn't case any issues like surging as the ecu will compensate, but it will cause increased fuel comsumption and if left long term then it can cause excessive wear on the cylinders in extreme cases.

 

[mph]

Thanks for the replies. Well I bought a new temp sensor today so going to fit it tomorrow and see if that makes any difference. If not will try the other suggestions