HDI more MPG

[KevinTW]

Right a few things.

My driving is pretty similar to yours in terms of being 60% motorway and im averaging 45mpg over 3500miles http://www.spritmonitor.de/en/detail/583387.html

A stage 1 map will increase your power but will also increase your economy.
A straight through back box, de cat and EGR blank (blank it properly in case its leaking) will also help.

The real best way of improving economy is narrower tyres. Swapping from 185 wide to 205 wide saw about a 20% drop in my MPG on the scan guage.

If you want to go really extreme stripping the interior out the car can give 5-10% better MPG

Can you find a blanking plate on Ebay as I can't? I could make one but for £5 I would sooner buy one. Cheers in advance.

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Right a few things.

My driving is pretty similar to yours in terms of being 60% motorway and im averaging 45mpg over 3500miles http://www.spritmonitor.de/en/detail/583387.html

A stage 1 map will increase your power but will also increase your economy.
A straight through back box, de cat and EGR blank (blank it properly in case its leaking) will also help.

The real best way of improving economy is narrower tyres. Swapping from 185 wide to 205 wide saw about a 20% drop in my MPG on the scan guage.

If you want to go really extreme stripping the interior out the car can give 5-10% better MPG

Can you find a blanking plate on Ebay as I can't? I could make one but for £5 I would sooner buy one. Cheers in advance.

Do you know of a decent straight through back box that won't break the bank or sound too boy racer.

[Dum-Dum]

EGR blanking plates were on ebay last time I looked.

For a straight through box that sounds good and is cheap use a second mid section cut up (see the guides section)

[Eeyore]

Sportex do some straight through exhausts. Cant find any ones for the diesel though and i dont know if petrol ones will fit

http://www.ebay.co.uk/itm/Peugeot-306-2-...51b3597709

and there is this for the dturbo. dont know if it will fit the hdi...

http://www.ebay.co.uk/itm/Peugeot-306-1-...51b3015611

this is where to buy decats for the hdi. Seller also has stainless ones but you can double the price for that.

http://www.ebay.co.uk/itm/Peugeot-306-2-...3f2a829359

and as for a straight through backbox. You can modify your old centre pipe to become a backbox. Its about somewhere. probably in the guide section.

and I believe that this is the egr blank you are looking for...

http://www.ebay.co.uk/itm/EGR-blanking-p...19d42fac1b

[KevinTW]

Thanks that is brilliant.

[cully]

he will want you to fit them when they arrive now srowell

[KevinTW]

MAF cleaner- is it any good? Will the K&N in my airbox for the last 6 months really have clogged it up. Sorry if this has been covered elsewhere. I want to cover every base.

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I am breaking a 1.4 hatch with a nearly brand new centre exhaust section. Would the centre box be suitable as a straight through back box for my HDI estate? My Capri mate Paul is a great welder and would make it up for me.
Think I am getting a bit obsessed.

[Just Sean]

80mpg in a hdi??

Tom will be jizzing

[Dum-Dum]

MAF cleaner- is it any good? Will the K&N in my airbox for the last 6 months really have clogged it up. Sorry if this has been covered elsewhere. I want to cover every base.

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I am breaking a 1.4 hatch with a nearly brand new centre exhaust section. Would the centre box be suitable as a straight through back box for my HDI estate? My Capri mate Paul is a great welder and would make it up for me.
Think I am getting a bit obsessed.

Chances are if you think you need MAF cleaner you need a new MAF. K&Ns eat MAFs (faster than HDi's do normally) because the oil off the filter gets all over them.


You want a diesel mid section as all the pertol one's have baffles in them and so aren't straight through. Id think the 1.4 one would possibly be smaller diameter too. A new HDi one is only about £20 ish from the motor factors though.

[Just Sean]

I have a working maf for sale

[KevinTW]

MAF cleaner- is it any good? Will the K&N in my airbox for the last 6 months really have clogged it up. Sorry if this has been covered elsewhere. I want to cover every base.

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I am breaking a 1.4 hatch with a nearly brand new centre exhaust section. Would the centre box be suitable as a straight through back box for my HDI estate? My Capri mate Paul is a great welder and would make it up for me.
Think I am getting a bit obsessed.

Chances are if you think you need MAF cleaner you need a new MAF. K&Ns eat MAFs (faster than HDi's do normally) because the oil off the filter gets all over them.



You want a diesel mid section as all the pertol one's have baffles in them and so aren't straight through. Id think the 1.4 one would possibly be smaller diameter too. A new HDi one is only about £20 ish from the motor factors though.

Cheers You are a cornucopia of useful information!

[Toms306]

80mpg in a hdi??

Tom will be jizzing

If he can average it over a whole tankful, I will be amazed. It won't happen though.

Even if it does....will the money spent outweigh the MPG gains...? Will have to find out!

[Dum-Dum]

Cheers You are a cornucopia of useful information!

I am indeed and this is why we have a rep button

[KevinTW]

Thanks for all the advice. New MAF came today. EGR valve single blank ordered, I hope the EGR isn't blowing or I will have to remove it altogether and blank the other end- I don't have octopus tentacles. Decat front pipe ordered. Steve at HDI tuning is devising a "Super Eco" remap for me. K and N airbox filter will be going on Ebay. I will keep you all posted on the results.

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Cheers You are a cornucopia of useful information!

I am indeed and this is why we have a rep button

Where is the Rep button you deserve some credit

[Poodle]

Rep button is bottom left of the post, figure with a speech bubble and green plus sign.

[KevinTW]

How long have you been running the k&n? It's probably eaten your maf, that'll knock a good chunk of your mpg, see if one of the local garages can check its wrking for you.

Thanks Poodle.
I changed the MAF and just sold the K&N

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If I ever sell the car, which is highly unlikely, can I remove the remapped ECU and put a standard one back in. Will the remapped ECU work in another 90BHP HDI?

[DeeTurbo]

I would check your brakes also. The sliders can go dry, pistons can stop moving so freely and both can cause the brakes to drag.

The seals in my front caliper had swollen and weren't allowing the pistons to retract so the pads were dragging on the disc ever so slightly. This caused my MPG to fall to 50. Replaced the seals last week and I'm now back up to 60!

I've had the rears dragging before and that was due to the handbrake mechanism going dry in the rear calipers.

[Toms306]

If I ever sell the car, which is highly unlikely, can I remove the remapped ECU and put a standard one back in. Will the remapped ECU work in another 90BHP HDI?

It's not that simple unfortunately, the ECU is coded to the immobiliser and the key fob chip.

You can use that remap on another HDi ECU though, as long as the ECU number matches exactly.

[Poodle]

If you ask steve nicely he may be able to hang on to your original map so you can put it back to stamdard if/when you wish.

[KevinTW]

I would check your brakes also. The sliders can go dry, pistons can stop moving so freely and both can cause the brakes to drag.

The seals in my front caliper had swollen and weren't allowing the pistons to retract so the pads were dragging on the disc ever so slightly. This caused my MPG to fall to 50. Replaced the seals last week and I'm now back up to 60!

I've had the rears dragging before and that was due to the handbrake mechanism going dry in the rear calipers.

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That happened to me on my old 405, I soaked the sliders in a load of brake fluid and freed them up little by little until the pins came out. Then loads of copper slip! I changed the pads all round on the HDI and copperslipped all the pins.
Cheers for that!

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If I ever sell the car, which is highly unlikely, can I remove the remapped ECU and put a standard one back in. Will the remapped ECU work in another 90BHP HDI?

It's not that simple unfortunately, the ECU is coded to the immobiliser and the key fob chip.

You can use that remap on another HDi ECU though, as long as the ECU number matches exactly.

Thank you. If this experiment is a success I will be hanging on to the car until it falls to bits and then I will break it!

[Kezzieboy]

Should do easily, I still reckon I can pass 80mpg with the 306 without getting too extreme. Kezzie has got me beat with something like 73 atm, but i'll get him.

Guiiiillllttyyyyyyyy

[DeeTurbo]

Should do easily, I still reckon I can pass 80mpg with the 306 without getting too extreme. Kezzie has got me beat with something like 73 atm, but i'll get him.

Guiiiillllttyyyyyyyy

73! How have you managed to achieve that?

[KevinTW]

Should do easily, I still reckon I can pass 80mpg with the 306 without getting too extreme. Kezzie has got me beat with something like 73 atm, but i'll get him.

Guiiiillllttyyyyyyyy

73! How have you managed to achieve that?

I would like to know too, do you just do motorway driving at 50?

[Poodle]

I think he mostly did it in one go - one end of the country to the other and back - drafting lorries the whole way. And he has 50 profile tyres which inflates the results and is blatantly the only reason he's winning at all. :p

[DeeTurbo]

I think he mostly did it in one go - one end of the country to the other and back - drafting lorries the whole way. And he has 50 profile tyres which inflates the results and is blatantly the only reason he's winning at all. :p

Ahh by cheating lol

[Toms306]

Meh, that 73mpg isn't useful anyway. His average is much lower. Average mpg is what matters....no-one drives at 56mph behind lorries all day every day.

[Poodle]

Kezzie obviously does lol. Tbh it doesn't matter how you achieve it, as long as you do it as an average across the tank it's still a valid result. I should be able to match that now, but totally cba with inventing a long trip and drafting lorries to do it, much more of a challenge to get it done at 65.

[Kezzieboy]

Yeah, just big old motorway trips. Even if you account for all the inaccuracies in the calculations and take it as an absolute peak it's still bloody impressive!

[Dum-Dum]

I'm slightly jealous of these uber MPGs, I've not seen 50mpg out of a tank in a HDi, Think about the best Ive ever recorded is 55mpg over a third of a tank.

[Danny2009]

Something's not right I've just done 120 miles to £15 half motorway cruising half flat out on b/a roads thts a 11mm td04 at 30 psi xud though need to come to the other side

[Poodle]

Dum-dum drives in binary, that should explain everything you need to explain his mpg.