Still haven\'t got used to a diesel engine (1.9 TD).
In cold weather, and when the engine is cold; the turbo has great pick up (primarily in 1st and 2nd; less noticable as gear go up; not felt in 5th) and the car feels like a rocketship (well, how I would expect a one and a half ton barge to shift anyway). The turbo also makes an audiable whistle, bit like a kettle; not deafening though. (again, only 1st and 2nd)
In warmer weather, and when the engine has warmed up; the whistle is rarely heard and the car seems alot slower (but not all warm days); though I haven\'t done any scientific testing.
Is this just down to the temperature of the air, or should I always hear the turbo whistle, or never? Or is this just normal?
Its just the difference between whistley turbo days and non-whistley turbo days feels immense.... and I figured you\'d feel it kick in in all gears, not just 1st and 2nd... Doesn;t wheelspin in 2nd in the wet any more either; though I have put new tyres on it...
Is it me (probably)?
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This is a complete guess, as I'm going on my Physics knowledge. Basically, as the air comes from the turbo and goes into the intercooler, it's allowed to cool down, compress, and hence you get more air (and hence more fuel) into the engine and therefore a bigger bang.
When the engine (and intercooler, presumably, has warmed up) the air isn't cooling down enough and so you don't get as much effect.
This doesn't explain your missing turbo whistle, though. On my 1.9 turbo Xsara, the turbo is just as good hot or cold. Loads of get-up-and-go in 5th gear.
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I wouldn't expect to feel as much of a 'kick' in 5th as i would in 2nd, because the car is unable to get through the rev range as fast due to the longer gearing - so i wouldn't worry about that.
It is true that turbo-diesels perform better when the ambient temperature is low, as the air is denser therefore more oxygen in each compression therefore more power, but i wouldn't have thought that a cold engine would perform better than a hot engine - i may be corrected though......
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Theory about ambient temperature is sound, but wouldn't this apply to petrol as well, modern fuel injection systems should be
able to produce optimum power for the conditions?
A diesel engines efficiency isn't affected by cold temperature compared to a petrol engine.
My Xantia was tweaked by Van Aaken and you could definitely feel
the kick in 5th, what it needed was a 6th!
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every pug or citroen turbo ive ever owned always goes like the clappers in cold weather esp 1st and 2nd and really takes off in 3rd,in warm weather there alrite ,turbos do like cold air better than warm,
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p.s that noise you hear could either be a hole somewhere in the turbo airintake or your exhaust tone as some turbos produce a kettle or police siren sort of tone,which is normal or pug and cit turbos.
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Ok, this morning, a significantly colder day, the car took off in fourth gear like it never has before. Hypothetically it went from 50 to 90 in half the road it would normally require, ahem.
This is not my imagination as the look of surprise on my face (hypothetically) would have stunned a mule at twenty yards.
Could the car be running rich? Would a rich mixture reduce power, with the denser cold air compensates for?
Or am I denser?
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If the car was running rich - yes, denser air would equate to more usable oxygen, however the performance hike you describe could not be attributed to this.
Sounds more like overboost from the turbo - wastegate sticking?
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Does the waste gate act in an on/off fashion is is it gradual with increasing pressure?
Is it possible I'm just used to under-performing turbo?
ie. Could my wastegate not be closing off fully, giving some benefit from the turbo, but not all the benefit?
Would a boost gauge help in troubleshooting?
What sort of repair bill would I be looking at if it was the wastegate; is it a do-it-yourself repair? (e.g. a can of WD40!)
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