my D2a TD5 is a pile of dog poo!

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Originally Posted by TonyC

Phil,
What are the two dips in the AFR at 65 and about 80 KmH? and is it normal for a TD5 to lean out at high revs like that?
I would have thought the electronics would have kept it pretty much flat line.

Tony

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i have no idea? that was never explained to me and i dont know the TD5's ecu well enough to explain it. its a bit contradictive though, lean AF ratio but drinking diesel??

just did a compression test and got 310-320psi per cylinder same as the other TD5 i tested, so the head gasket was deffinatly dead. pitty as i was hoping the recoed head would have fixed all my problems.

cheers phil

thanks for the info pibbly,
i think ive replaced everything that has a bearing on the AF ratio.
i havent had the standard mapping or the new ecu on the dyno to compare but i do know i can see very high EGTs with the BAS mapping 200deg+ higher than the stock mapping, but that said the stock mapping returns the same fuel consumption??

cheers phil

this is not a bad read
http://autospeed.com/cms/title_Commo...4/article.html

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Compared with petrol-powered engines that most often run with stoichiometric mixtures (that is, the theoretically correct air/fuel ratio for complete combustion, which is about 14.7:1), diesels use very lean air/fuel ratios. The air/fuel ratios for diesel engines under full load are between 17:1 and 29:1, while when idling or under no load, this ratio can exceed 145:1. However, within the combustion chamber, localised air/fuel ratios vary – it is not possible to achieve a homogenous mixing of the fuel with the air within the combustion chamber. To reduce these in-chamber air/fuel ratio variations, large numbers of very small droplets of fuel are injected. Higher fuel pressure results in better fuel atomisation, so explaining the increase in injection pressures now being seen.

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Originally Posted by discowhite

this was what i thought it was. my reasoning behind it was a few months after i had it on graeme coopers dyno i got thinking about something ward said. ''its making plenty of power but the EGT's are too high for my liking and its running lean although, its not blowing as much smoke as most chips ive seen, its one of the better ones''

so i though..how does a diesel make good power not blow lots of smoke and run lean??
lean can = high EGT's and i thought, after seeing the head and head gasket and the lack of compression that i was just using more accelerator to make the D2 drive?
the fuel rail in the head is almost imposible to test. the best i could do was fit a FP sender in the reg and block the return to tank line and use the fuel pump to supply the pressure, there wasnt any bleeding off of FP...but...who knows what its doing when its hot and under pressure:eek:

cheers phil

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It might be worth pulling the exhaust manifold off and having a look for any variation of the colour of the exhaust ports (or perhaps a clean one)

You could also try testing the fuel gallery in the head for leaks with a similar system to what you have used but with air rather than fuel to pressurize the gallery. Leave it under pressure over night and look for bleed off the next day. I did a similar test on the heater core of my Disco 1. It doesn't take much to pressurize - I just used a bike pump.

have you got one of the BAS boost modulator doo hickies fitted?

is your tank still the same size.....hasnt been damaged or collapsed.....?

youre talking kms/tank instead ltrs/100kms......




theres other things that can affect economy......
centre difflock.....brakes dragging.....wheel alignment.....crap fuel......blocked airfilter.....

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Originally Posted by Blknight.aus

have you got one of the BAS boost modulator doo hickies fitted?

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not yet, but the over boost issue is only a few day old unlike the consumption and idle prob.

cheers phil

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Originally Posted by DEFENDERZOOK

is your tank still the same size.....hasnt been damaged or collapsed.....? if it was collapsed it would have to be 1/2 the size of the tank fitted, think ide see that;)

youre talking kms/tank instead ltrs/100kms...... sorry, figures are 430/tank (90ish L) thats 20.64L/100k, 13.69mpg and 4.84klm/L




theres other things that can affect economy......
centre difflock yes it works no its not locked.....brakes dragging as i mentioned in a previous post done all that bout 1000klm ago, new vented rotors and OE pads, checked all the breaks and bearings.....wheel alignment was done 800k's ago when the new tyres were fitted.....crap fuel im using that much fuel its not the diesel, from caltex, bp,mobile......blocked airfilter just changed last week.....

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im getting slightly cranky with this car, ive been working on motors and plant over 15years now. this is not a simple problem if it were i wouldnt be asking.

cheers phil

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Originally Posted by awabbit6

It might be worth pulling the exhaust manifold off and having a look for any variation of the colour of the exhaust ports (or perhaps a clean one) i did this when i pulled the head off, all ports intake and exhaust were equal in colour as were the piston tops all had a nice star pattern on the crown.

You could also try testing the fuel gallery in the head for leaks with a similar system to what you have used but with air rather than fuel to pressurize the gallery. Leave it under pressure over night and look for bleed off the next day. I did a similar test on the heater core of my Disco 1. It doesn't take much to pressurize - I just used a bike pump.

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this can be done, just need to get another reg and barstedize it, but, as im using double the amount of fuel anyother td5 uses, a crack in the head leaking into a cylinder would fill the sump in no time, its not doing this. and if the crack were in an intake/exhaust port the port should show some signs of washing or at least discolouration or maybe even a different texture. and funny things would happen to the coolant if it were leaking into a water jacket.

cheers phil

I'll preface this by saying I know sweet bugger all about, well, anything. Particularly computer controlled diesels. So don't even bother responding if its way off the mark and I need to learn more... :D

If the timing per se was a little out, ie it was injecting at the wrong moment in the stroke, wouldn't the injection pressure sensor (is there one?) think its got a higher/lower pressure than it should and hence push the pump harder to make up for the irregular pressure? The extra fuel would then compensate for the power loss that a non ECU engine would display. Since diesels run with an abundance of air it should theoretically still burn completely if the squirt was a little early giving it enough time to properly burn.

So what tells the injector when to squirt? Is that the crank angle/position sensor feeding back to the ECU or is it purely mechanical with the timing belt?

If that was plausible, it'd be why the majority of sensors, cooling system, exhaust system etc didn't make a difference while excess fuel consumption is still the only symptom.


As I said before I know little about anything useful, I can't even fix a 2.25P properly :D
But I hope you get it sorted

Just a dumb question as I'm no mechanic, but as a last resort have you tried unplugging and replacing the entire ecu and then seperately the cables by swapping with a standard spec unit from another disco?