Wasn't sure how best to title this thread as it's gonna be a long one with lots of info so please bear with me...
Picked up a 54 plate Signm 2.0 dti elegance at the start of the month. Very impressed with the spec for the price. Wasn't too impressed with the performance but, as mentioned on here many times, 100BHP isn't a lot for what is quite a big and heavy car so thought I'd learn to live with it.
It seemed to pull ok once you hit 2k revs so thought 'it's because its a diesel...'. However, I didn't just have to be heavy footed with it, for anything like decent performance, it was pedal to to floor, literally.
Then I started to notice it was quite thirsty, especially after reading that this was a fairly economical engine. 30-35 mpg although the trip computer was saying 45-50? Trying to drive more economically (read, slowly, very slowly) didn't change this to any degree so went back to the 'no throttle/full throttle' style I had adopted and started to read on here for ways to improve mpg and performance. Pencilled in air box mod, K&N filter and cleaning the EGR valve and poss boost sensor & MAF sensor as things I'd be able to do (when I had time....)
I had a couple of long drives planed (leeds-newcastle and back, then leeds-portsmouth and back in a week), so bought some millars, couple of shots of this in the tank and by the time I was in Portsmouth, it did seem a little bit quicker below 2k revs buy only a little, it could easily have been wishful thinking.
Got back to Leeds and had an early start the next day, it was a cold morning and it wouldn't start! Well, it took 5 attempts and it started. Seemed a bit slower on the drive in to work but was fine in all other regards. No engine warning lights or anything.
Went to get some lunch in the car and it would not start at all. It would turn over fine, the engine would fire up and cut out immediately. Try again, engine starts then dies.
So I called the AA. Chap ruled out a fuel problem straight away (can't remember why though, lol), this was my main worry due to the cost of fuel pump etc and the engine did seem starved of something. So the AA chap checks the air intakes. This is where it gets interesting...
The butterfly valve on the throttle body (i think it's the throttle body...it's directly above the EGR valve) was shutting as soon as the engine fired up. This butterfly valve is vacuum operated and the vacuum would kick in as soon as the engine fired up, shutting the butterfly valve and killing the engine (apparently this is how the engine turns itself off, makes sense...).
The AA bloke disconnected the vacuum, engine fired up fine and revved fine, really well in fact. Connect the vac pipe, same thing, it died. The vac pipe lead to a vacuum valve (directly above the radiator, on the right hand side when looking in the engine, there are two of them side by side), the AA man carefully 'tapped' it, reconnected and engine fired up fine. The 'tap' had obvioulsy released the stuck valve.
When I went to finally get some lunch (I was starving by this point!) I had to double check I'd gotten into the right car! It was pulling like the 1.9TDI company Golf I drive occasionaly! And this wasn't even going past half throttle!
Clearly, the air intake has been restricted the whole time I've had the car.
Haven't drove it enough to see if the mpg is any better but the readings on the trip computer have dropped dramatically, the current reading is staying between 30-40 mpg which is where the actual mpg was before. It used to read in the high 40's +.
So, as I was on day 28 of my 30 day warranty from the car people (I know, car supermarket and all that, just didn't have the time to hunt down a decent private sale), I've called them so they can replace the stuck vacuum valve. However, as there are some very knowledgable people on here, I wanted to run this past everyone, incase it is another component that needs replacing or is causing the issue. As the car now seems to be starting fine and running better then ever, I can see the car peoples engineers spending all of five milliseconds on this, I'll be lucky if they actually replace the vacuum valve!
Thank you to anyone who has actually read this far. Lots of info, i know....