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Discovery weight 'Vs' performance drop


streaky
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Wierd question.....

My Disco has a 4.6efi hot wire now and yet I'm not so chuffed at the performance or it's even worse fuel consumption.

After some trouble shooting my workshop has had the truck weighed and came up with a figure of 450kg over the top of a standard Discovery Series I. 98' model.

The increase in weight consists of ARB Bull bar 50kg with Ramsey winch 30kg, two optima batteries 20 kg, Wolf rims shod with 265/75 R16' BFG AT's KG????, two stainless steel underbody fuel tanks weighing 60kg combined, Front runner roofrack 30kg approx, rear load draws 25kg approx.

Thats a breif list of the weighty items accumilating approx 270kg.... I can't yet see where the rest of the figure has come from but will find out when I return to UAE next week.

I went to visit the boys at V8 Developements last week with JW, they seem to think that 450kg would slow the truck down in terms of accelleration and general grunt but I'm still not 100% convinced it would effect the fuel consumption that much.

I was getting approx 250-270km to the tank full (90lt) this seems really bad to me even with a truck weighing 450kg more than standard.

V8' D's had some great inputs about enough air getting into the plenum. I currently run a Mantec snorkel and regular OEM airfilter. The K&N's let in far too much powder sand for my liking.

Assuming the engine is tuned to perfection with a Kent 268 cam, vernier pully arrangement and a Mark Adams 4.6 Tornado chip.... do we think I'm over reacting to my poor fuel ecconomy or should this be expected?

Thanks.

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Depends how you drive it really, you can get shockingly low MPG from a big V8 if you've got a heavy right foot. 450kg is a significant weight to be towing about the place too.

270km on 90l is not good - the 109 (4.6 V8, RP4 cam, MS'n'EDIS) can touch 20mpg if I drive sensibly, which would be the best part of 400m / 640km on 90l.

Does your ECU use lambda sensor(s)?

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450kg is only a bit more than an empty Sankey trailer and I sure notice that when it is on the back of the 110... I haven't checked the fuel consumption but as a lot more foot is required to maintain a similar amount of progress up hills etc I guess it would make quite a difference to the mpg

having said that I can fairly easily get 300 miles out of my V8 on a long run - 230-250 if a lot of round town driving is involved. And the roads here aren't great for MPG i.e. lots of hills etc - if you are only getting the same km as I am miles then that is a big jump :o

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FF.... no lambda sensors.... so I can't really put a wide band sensor anywhere easily. I laid that out to Mark when I ordered the chip and the cam.

I've been driving the truck very sensibly for the past few months in an effort to gauge the milage...but no matter what I do the MPG is appauling.

During a recent strip down of the head and whilst changing the cam I was simply gob smacked at the ammount of carbon deposites in the heads. I put new valve stems, re-seated the valves etc and put twin springs along with the cam kit.

I just think that a 4.6 in good running order should be able to cope with any additional weight that I throw at it. Me thinks that towing a sankey should not affect the performance that much unless I'd tried towing it without any wheels on the thing.

My talks with V8 D's came up with some plausible suggestions.... first of which to ensure that the timing is spot on when done with the varnier power pulley that came with the cam.

Next up I have to ensure that it's getting max air into the heads.

At this time I'm just fishing for information and suggestions before I return to Dubai on Sunday.

Thx.

S

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Sounds like the ECU is just over-fuelling then, with no closed-loop operation it'll just be chucking in whatever fuel it thinks is right. This is why I don't like "chipped" ECU's, unless you tune it to your vehicle it'll never be right for your vehicle. At best it'll be a close match based on a very similar engine.

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  • 2 months later...

Alrighty then....one of these puppies has arrived in the post from down under. It's a http://wbo2.com/2j/default.htm

Now I have to install the sensor. Anyone on here ever done that before? Apparently they work best in specific points of the Y peice. My exhaust doesn't have cats or bungs in-line so we'll have to weld a couple in.

Once it's in I'll be able monitor the situation and possible get it to talk to my ECU. Another mail to Mark Adams coming on.

Anyone got any comments or inputs? Fire away... I'm all ears.

Thx.

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Thx FF. It's a 14CUX with a Mark Adams Tornado chip.

Does this sound goofy.....?

It's a common rail fuel injection system right. How about putting three bungs in the exhaust? One on each bank before the Y peice.... and a third after the Y peice.

That way I can see whats going on with each bank independantly and also as a combined figure.

If one bank of cylinders was showing really rich (for example) then I could try to pin point the injector etc. Any thoughts on the matter or am I trying to out think myself?

Also...where is JW Riyadh these days? I might call him up later....last I recall his internet access was being turned upside down.

Thx.

S.

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If one bank of cylinders was showing really rich (for example) then I could try to pin point the injector etc. Any thoughts on the matter or am I trying to out think myself?

It makes sense but the extra fuel is less likely to be an injector than just a variation in the engine itself, you have to ask yourself how bothered are you about hunting for a minute difference that car manufacturers and all but high-end race engines never bother with.

If you stick three bungs in you'll only worry about trying to balance the banks and then you'll end up wanting a bung in each port of the manifold...

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Cheers.....one bung after the 'Y' peice it is then.

Does anyone know whats happened to Mark Adams? He used to be very responsive to mails but since I've had potential issues with the chip he doesn't respond to my questions. Very frustrating....perhaps he's on an extended holiday.

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Does your ECU have an input for O2 sensors, and if so how does it use them? If the input is disconnected and left floating that may be why it's chucking in so much fuel. It may equally be the case that the chipping ignores O2 sensors completely, it depends how it's set up - and you'd need Mr Adams to tell you that much.

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is the chip a physical soldered chip on the mainboard or is it a piggyback ecu type affair?

if easily done, the first thing i would have done is remove the chip to ascertain whether it is the chip that is fubarred and causing the problems. it very well could be!

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FF & JMZ.

I sent my original 3.9 ECU back to Mark in the UK for re-chipping. He asked me about O2 sensors & cats at the time of ordering the chip.

I've sent him some mails and await a reply.

Part of my test strategy is to swap the ECU with a standard 3.9 one. I've got a whole bunch of other stuff to do as well but getting the O2 sensors in place is number one priority.

I really need better fuel mileage between fill ups more than I need fuel economy. I filled up all three onboard tanks last week for a 600km desert drive & it cost me 38 quid for 210lt. What worries me is running out of fuel...not what it's costing me. I should be getting 900-1000km between petrol stations so I don't have to bail out early searching for more petrol.

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Okay, these are UK prices and streaky isn't using LPG, but...

Tdi - Diesel £1.09/litre - 30mpg = 16.5p/mile

V8 - LPG 46p/litre - 15mpg = 13.9p/mile

Still feeling smug?

Tdi - Veg oil 0p/ltr due to collecting from pub = 0p/mile

errr yes :P

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Quick update.

The good news is JW's back on line after BT dropped the ball.

The bad news. Dutch git has found his way here....joking mate! Welcome!

All parts have arrived from Ozzie & are ready to fit. Waiting for my new company car to arrive so I don't have any pressure to get stuff done in a hurry.

More good news. Sean from V8 D's will contact Mark Adams and inform him that my mails are not spam. He's unindated with mails from folk trying to pilfer his vast knowledge and then not ordering the bits...I can't say I blame him either.

I have a huge check list from V8 D's on some trouble shooting methods.

Question.

I'd like to know if the O2 sensor can talk to the ECU and adjust the figures that way? Mark was aware that at the time of ordering the new chip I didn't have lambdar sensors or cats.

Possible? or am I talking toilet?

Alex....The Discovery was designed carry 4 adults and 75kg of luggage without compremising the fuel economy by more than 15%...so even with the roofrack (which was taken off for a while to confirm the mileage) bigger rubber etc I still think the economy sucks. Excessive weight would not coke up the heads either. I've had them off twice in 30,000km and couldn't beleive the state they were in.

The purpose of me purchasing the wideband sensor is to help confirm that the engine is not running within it's design perameters.

Hotter air theory. I am running a raised air intake with 3" bore. Current temp in UAE...same as UK in Spring. Just nice and occasionally crisp.

Thanks for the inputs though.

Regards.

S.

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Be interested in the results on the wideband, should be running about 14.7 when cruising along and maybe down to 13 - 14 when floored, if its running 13's when cruising then that might explain the poor economy and the coking up on the heads

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