Tired Megane 1.9 tdi?

My '97 Megane Scenic with the 1.9 tdi engine feels very tired at low revvs. Taking of at lights or going uphill at low to medium speed is somewhat of a problem sometimes. However, at 1750 rpm the engine suddenly kicks in, and everything is fine. Highway driving is ok, mpg rating normal and there is no abnormal smoke. A subtle, but audible, whistle from the turbo indicates that it's working properly at part of the register at least. Is this normal, or do I have a boost pressure problem? It's my first diesel, so I don't really know what to expect. 1750 rpm is admittedly a low speed, but the car is highly geared and it feels like the torque is needed already before this speed.

Thanks,

Daniel

Reply to
Daniel Noreland
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Bad case of turbo lag?

Reply to
Old Fa*t

Most turbos whether petrol or diesel, but especially so with diesel, feel gutless until the turbo kicks in.

Reply to
Conor

Has it just started doing this, or has it always done it?

Most turbo'd engines have lower compression ratios than their non turbo'd counterparts. The turbo also creates a restriction in the intake and exhaust at low revs (and usually at very high revs too).

As a result, when off boost, turbo'd engines are not very responsive and feel a bit flat. 1750rpm sounds like a perfectly normal time for the turbo to spin up and provide some oomph.

If the car has always done it, its probably a characteristic of the engine and nothing to worry about. If it definitely used to feel different then you might want to start looking closer at things like the condition of the boost pipes and intercooler (if it's got one) and how heavily it uses oil etc.

Reply to
Douglas Payne

The turbo on my escort kicks in at 1950rpm, and revs it all the way to

5150 before the limiter hits.

Sounds like yours is working as designed to me.

Reply to
Paul Cummins

I recently bought the car, so I don't really know.

It doesn't feel like a bad case of turbo lag, as someone suggested. There is a quite distinct boost at 1750 rpm, almost regardless of the driving conditions. Below this engine speed, I can rest my right foot against the floor without much happening.

I guess I'll just have to test another specimen before I do any serious tearing apart of things, and I can live with it if it turns out to be the characteristics of the car. It's just that I feel a bit cheated on the reputed bottom torque of a diesel. With so little "pun" in the engine, it ought to be put in one of the lowest insurance ratings, but it's average. My old atmospheric Saab 9000 (gas) feels like a racer in comparison. I'm really only after an economical family car that gets us from A to B, but is it too much to ask for to be able to start uphill without excessive revving and clutch eating, having to go down to 2nd or even 1st gear at street corners etc?

-Daniel

Reply to
Daniel Noreland

That's what diesels do, squire.

That's also why I despise them.

Reply to
Pete M

I suppose it's possible the MAF (Mass Airflow Sensor - if it has one) is not working correctly , this caused my car to be sluggish at low revs, but also affected it higher up the revs - although less noticeably.

Take it in and get it looked at - Or try another *friends ?) .

Diesels 'are' more sluggish at lows revs - as they are diesels ! - compared to a petrol. It might just take some getting used to ?

Graham

Reply to
Graham

My guess is that it's fine, but that doesn't mean that it is!

There is generally very little turbo lag on such engines, the turbo is often quite small for the engine capacity, which allows it to be making good boost at relatively low rpm. The engine perhaps just doesn't produce enough exhaust to make the turbo effective below a certain speed.

Low down torque is a characteristic of diesels, some of it is sacraficed when a turbo is added, and it's made worse by the way it feels so much slower when off boost compared to when on boost. Power delivery is very different to a NA petrol car.

As you say, try some other specimens, and, forgive me for saying this, adjust your driving to suit the car. If it turns out your car is normal and it bothers you that much "having" to change gear and burn the bejeezus out of your clutch, get another old petrol SAAB. (c:

Reply to
Douglas Payne

Sligtly OT, but interesting nevertheless; how much of the diesel's advantage over petrol engines in low load city cycles (lower intake losses since no throttle) is lost due to the turbo? Would some kind of turbo by-pass mechanism (perhaps a bit too complicated) make a noticable difference?

-Daniel

Reply to
Daniel Noreland

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