Low-ish power and mpg issue

[Deleted member 74601]

Since I bought my Seat Leon 1.6TDI CR, I have been having varying fuel consumption results. I was told to adapt my driving style, and that has certain helped, however, I definitely think there is a problem with the car.

The problem I've noticed, is if I start the engine from cold, and let it get up to temperature, it NEVER reaches full efficiency, and it feels like an engine with 80BHP instead of 105BHP.

If I then stop for around 10-15 minutes, and turn the engine back on (whilst it's still warm), the MPG takes a massive jump up, especially on the live data display. The power also feels like it should. This is how I would have thought the car would perform all of the time.

I decided to do a test. I started the engine cold, got it up to temperature and went to the motorway nearby. I reset the trip when I reached 70mph, and stuck cruise control on. I did a 10 mile journey to the end of the motorway, made a note of the reading, and then did the exact same thing back up the other side (waiting until 70mph to reset the trip etc). I averaged the two readings. at 52.9mpg.

I then stopped the engine for 20 minutes, got a cup of tea etc. I then did the exact same test on the exact same bit of motorway. The average mpg this time around was 65.4mpg. A MASSIVE jump.

Do you have any idea what could be causing this? Someone on another forum said they noticed similar symptoms in a Mondeo with a faulty temperature sensor/thermostat. I've also read that it could be the MAF.

I have fully activated VAG COM, so if anyone could suggest anything I could be maybe monitor to take to SEAT, because, as usual, I'm just getting the old 'we're not having an issue when we drive it'.

Thanks guys

 

[Ryanoceros]

Il second this my ecomotive is somtimes alot more powerfull then it usally is.
People have mentioned dpf regens but I know it's not when a regen is occurring.
And as for cold starts somtimes it's runs proper lumpy on start up and other times it dosent.
As for mpg that varies to. Like when I drive home from work it's at 45mpg and others it's 36 ish.

 

[Deleted member 74601]

Yeah well my car has gone in this morning, and I actually lied about my fuel economy to get them to look at it more. I said I was getting 50mpg average over a tank and was told this was the best I was going to get.

I have definitely noticed it though. I obviously did the above test, but also when doing urban driving, from cold, bringing it up to warm, I get about 50mpg when it gets warm. However, if it's turned off and started warm again, the mpg jumps up to 60mpg urban.

I'm seriously tempted to just try and replace stuff myself, because, as usual, I'm going to get no where with the dealer.

 

[Hockey Guy]

I too will be interested to see your findings. I have the normal 1.6TDi (Not the ecomotive version) and am averaging about 50MPG so far. Granted, the car is still new and only has less than 1200 miles on the clock, but am hoping that before too long I'll start seeing averages of about 60MPG on day to day running.

Being realistic, I don't expect to get anything close to the claimed average of 67MPG unless I get a "perfect run".

Will be monitoring this thread with great interest.

Tom

 

[Deleted member 74601]

Well like I say, when the engine is started warm, I can get around 67mpg on the motorway, it's the poor performance when started cold that's affecting it. I can understand it being poor whilst the engine is still cold, but even after an hour of driving the performance is poor compared to when I restart the car warm.

If they don't change anything, I'm going to try a different dealer. Personally I'd be inclined to look at the thermostat, i might even just push them to replace it because the sensor doesn't cost much.