1.5 DCi (80) Kangaroo at 30!

[WJAM29]

Hi,

I'm new to this forum and have recently bought a 2003 1.5 DCi (80) Megane. The car has been driving fine but on 2 occassions I have been travelling at 30 MPH in forth gear at about 1.5K revs and the engine has felt like its going to stall. There have been no lights on the dash come up and by moving down to third gear it goes away. Am I asking too much of the engine, I have come from a 1.8 petrol engine. Or is there perhaps a sensor in the engine bay that may need some TLC. The car has done 58k mikes so far.

Any ideas?


Many Thanks

Will.

[busternlouie]

I would say 4th gear 1500rpm 30mph is labouring the engine too much and is likely to stall

[DJC013]

I would say 4th gear 1500rpm 30mph is labouring the engine too much and is likely to stall

Hello, i would agree with this post, 30mph in 4th is wrong gear selection, regards Damian.

[WJAM29]

Hi,

Thanks for the replies.

I think I'm probably just used to the bigger engine. I'll drop it down to 3rd see how I get on.

Many Thanks


Will

[chris2008]

i disagree with this, i have a 1.5 dci (100) and i can put my cr in 5th gear at 30, but i do it to save fuel, lol ,

[pw981]

Hopefully alexB or anyone else can provide a more technical reason to this post, but here goes anyway.

Driving around below 1500rpm in a diesel will be doing no favours to the engine, or fuel economy.

Think of one riding a bike - once you've reached your riding speed do you then select the highest possible gear, to make your legs ride the pedals slower, or stick to a gear which is more comfortable even though your legs are riding the pedals faster? Which gear would cause your legs to struggle more for each pedal you take?

Sorry if this post sounds rude or anything, its not suppose to be.. just I'm a bit short on time at the moment!

[AlexB]

I agree with freddymercurystwin -- there should be no kangarooing at 1500rpm.

The other question is whether it is good or not to drive in low revs. The efficiency of a diesel drops below 20% of the calculated load. Under the low revs the maximum calculated load corresponds to lower power output, so one ends up using a higher calculated load and therefore better efficiency. However, if you take it to the extreme, reducing revs to idle, then other effects will start playing a significant role... All in all, 1200rpm when slowly rolling without any acceleration or 1500rpm in town are OK for the engine. It is up to the driver to think about safety -- the acceleration will be poor in low revs plus a noticeable turbo lag. BTW, any increased loads under low revs are not good for DMF!

[WJAM29]

Hi Guys,

Thanks for the replies,

Does this mean I have something wrong with the engine? Is there any easy way of testing it?

Many Thanks

Will.

[AlexB]

Yes, there is something wrong, I am afraid. Check the obvious things first: drain water from the fuel filter (bleed screw on the bottom) and check for bubbles in the clear fuel pipe to the pump. Then get ELM327 (£30 on ebay), read the stored fault codes and record the engine parameters while driving.

I hope, you've checked the service history and have read the service schedule in your service book...

[WJAM29]

Hi,

I'll have a look at it this weekend. The service book shows a service at 15K, 32K and i think 51K. Although I know it needs its cambelt changing.


Many Thanks

Will.

[chris2008]

tryed mine today at 30mph in 4th gear it was fine, just a normal diesel