MPG

[blackbess]

Can anyone tell me what the official MPG figures were for the 405 non-turbo diesel please?

Last weekend we got 710 miles out of 62 litres, which I'm really pleased with on a 180k engine, but just wondered how that compares with the official test figures from new.

Cheers, BB

[Piston Broke]

It depends what you mean by 'official'. The Euro tests were incredibly loose until the late '90s, making any Government test claims unreliable, and liable to differ greatly from country to country. You can look in the handbook to see what Peugeot claimed, but that itself can often be a work of fiction.

62 litres is 13.65 gallons imperial gallons, which over 710 miles gives you 52MPG, which is about par for a healthy 405 diesel, and about what my olde GRDt used to return.

Interestingly, the difference between NA and turbo consumption is virtually nil (unless you use the turbos extra performance and boot it everywhere) because depsite the extra weight and engine output, the TD is thermally much more efficient.

As a comparison, my 406 HDi was a little thirstier than the 405 about town, but much much better on the motorway, possbily aided by better gearing and aerodynamics?

And the latest generation is a step backwards. The 2.0 HDi 407 can be a surprisingly thirsty beggar, with many owners stuggling to better the high 30's overall, which makes them barely any better than the petrol engined versions. In real life the diesel 407s tend to give worse than the laughable Euro consumption claims, while the petrol ones do somewhat better.

I squeezed 303,000 miles out of my 405, so if you keep yours well maintained you've got a few good years left with her yet.

[blackbess]

Cheers for that - in fact when I got the car 2 years ago it was a bit tatty and neglected, new exhaust and thermostat I think have made the biggest improvement and then other minor bits will have helped as well. Ditching the bizarre cobbled-together fuel filter system and plugging back in the original one with integral pre-heater has boosted performance no end, and getting about 10% extra miles to my gallon was the icing on the cake. Still a bit of room for improvement though.

At the time these were built a Pug diesel was by far the best, so I'm confident you're right about having plenty of years left in it. Thanks for your reply.

[Donaldiesel]

My 305 estate has a similar XUD9 non-turbo engine with lucas pump, and I regularly get 47 - 52 mpg mixed driving. This car is lighter than a 405 and the the only external engine driven ancillaries are injection pump, alternator and vacuum pump. Based on your 52mpg from a bigger car I should probably be getting more. However, the car has done 250k so I am not complaining.
Please tell us more about the improvements to your fuel system. My XUD has a remote fuel filter as standard, which is no longer heated since the original broke.
Interesting comments on hdi from Piston Broke. Direct injection is supposed to be more fuel efficient. However, cars are becoming heavier, taller and have more engine driven equipment. It would appear that the improvements in engine technology and aerodynamics have not kept up with the power demands. But the biggest variable is how fast you drive and how hard you accelerate. The manufacturers 'work of fiction' will possibly be achieved by a computer driving on a test bed.

[blackbess]

Firstly to be fair the usual mpg is a little lower, the 52 was over one 700 mile trip of mostly motorway and some minor roads in the hilly Peak District. So I'd have thought your 47-52 is probably slightly better than mine on mixed driving.

The car was originally an STDT. About 6 years ago it had an engine swap to a standard non-turbo XUD, though it turns out from the engine number it's one of the ones made under licence at FSO Lublin and has an engine code of 10CU7D, but that is an XUD equivalent. The bloke who did the swap thought there was a problem with the pre-heating filter on the engine, so he bypassed it and used the original, earlier canister filter off the original engine which bolts to the battery tray. He also fitted an in-line disposable filter and ran the fuel line over the back of the engine - over the exhaust manifold.

Earlier this year the bleed pump failed on the canister filter, so I got hold of a bulb type bleed pump, fitted that, and refitted the filter on the engine - so the fuel is now pre-heated as it should be and economy and performance have both improved.

When I first had the car the exhaust was gone, so a new one obviously improved things, then I discovered a water leak, fixed that and it made not much difference. I always thought the engine was overcooling but wasn't sure if it was just an error on the gauge, until I drove 200 miles in the snow and realised there really was a problem. It turned out to be a tiny tear in the thermostat seal, so water was circulating immediately and in cold weather she never had a chance to get warmed up. That made a huge difference to smooth running and economy.

Finally, I don't understand how or why, but it seems to make a difference if you follow the handbook to the letter and set the idle speed then the anti-stall speed as they say. That I'd love to have explained as I really don't get it!

[Donaldiesel]

Hello, your preheating results are interesting. Your original engine would have had a fuel preheater on the waterpump manifold - hidden low down at the back of the engine. Hence the canister filter housing on the battery tray is not heated. (Earlier cars had a heated canister filter). My canister heater is broken, so no fuel preheating. I am now inspired to reinstate this.
The radiators are pretty efficient on these, and the non-turbos rarely get really hot. Just as well, because with an iron block and alloy head, overheating can do permanent damage.
Do you have a Lucas or a Bosch injection pump? Also, how is the cold start fast idle controlled on yours? If this device remains on fast idle/fuel enrichment all the time (they can get stuck) it can certainly mess up the economy.

[blackbess]

Hi DD, My old preheater would have been missing if it went with the engine. Must admit even in the summer I very rarely hear the fan come in, sometimes wonder if it even works (but it does). I well remember the Morris A-series cast iron / alloy combination which used to get blocked waterways so I know what you mean about problems - 2 heads warped in a year!

My pump is the Bosch one. Not sure what controls the cold start, all I know is the cable at the back of the pump adjusts it and there is a stop lever screw that can be adjusted at the end of it as well - someone mentioned a wax capsule on here a while ago? When I got the car the guy who had it before had upped the idle speed to about 1050-1100 using the accelerator cable adjustment but also set the idle speed to around 1000. So it was on cold start settings permanently. I just undid everything and started again. I did think at first the cold start may have been stuck on but it turned out not to be.

Just a final note on the idle, after putting it all back to where it should be it took some weeks before the engine "settled" into better performance and efficiency.

As an afterthought - don't they tend to overcool if there is air in the waterways?

[Donaldiesel]

Air in the waterways is bad news. It may cause hot spots and local overheating not apparent in the overall coolant temp. That is why it is important to bleed the air when refilling the coolant. XUD engines have several bleed screws in the cooling system for this purpose.

Probably me who mentioned cold start wax capsule before. Yours is releasing the cold start lever when warm, which is good.

Regards,
Donaldiesel