What I understood from the "hot start fix" is that it is basicly switching the input from the motormanagement to ground perhaps via a resitance according to a "cold" value of the sensor) at starting and as the engine runs, it is switched back to the sensor.

this way the engine will allways start with the setup for cold.... meaning glowplugs (not important when engine is warm) and adjusted injection timing.

people say it is caused by the timing chains that stretched, but after rebuilding my engine with new chains I still have the issue of bad starting when warm

 

I'm not 100% sure as I've never owned a diesel one... but I thought the hot start problem was due to wear within the FIP itself? and the adjustment in timing was also just to 'offset' the wear in the pump itself.

Could be wrong - as I say, I've never owned a diesel one, and been in one which has been running completely sweetly either!

 

The problem is indeed usually wear in the diesel injection pump, along with general wear and tear. The BMW engine management tries to start as lean as possible to reduce emissions (unlike for example the 200/300Tdi that start easily but always with a puff of smoke). With a warm and worn engine, the lean strategy can't always cope. By fitting a resistor in series with the temperature sensor, the engine management will think the engine is cold(er) and will add extra fuel, allowing it to start more easily. I used a 500ohm resistor, switch via a timer that remains active for 20-30sec after turning on the ignition. Afterward, temperature readings and thus fueling are back to normal.

Filip

 

i have moved the inj pump on several m51 engines. all you need to do is remove the air intake pipe across the top of the engine,mark the pump body and timing cover (a scratch will do. loosen off the pump mount nuts, inc the one on the bracket near the back of the pump, then twist it towards the engine by about 1.5mm(might need to use a screwdriver to twist it as the inj pipes will hold it in place). then do every thing back up. one engine i did needed about 3mm. run engine or go for a run,then see if she starts when warm

 

I was looking at that the other day or at least reading about it, the pump move I mean. Don't you need a special pin to get the set up right? Or can you just do it by eye.


If I was to buy the quick start does anyone know what wires I need to cut or splice into. Part of me wants to do the pump but I worry about messing it up. Why do you need to mark the lines?

Thanks for your help everyone

 

Marking a line is so you can see how far you move the pump. This also allows you to go back to the old setting should the adjustment not work for you.

 

Ok that makes sense, I'm going to look on YouTube to see if there's a vid of it being done. Isn't there a hole that needs to line up to get the setting right, a hole that you stick a measurement pin into, or do I ignore that and just adjust it a mil

 

just mark the body and timing cover and move the pump by about 1.5mm this should improve hot starting,if it still plays up move it but a touch more

 

Before you install any "hot start fix", change the thin vacume hose between the intake manifoil and the MAP sensor on top of the fuel filter. 4 mm hose if my memory does not fool me. The old hose tends to get clogged and a new hose can do miracles to the hot start problem.

 

Before you install any "hot start fix", change the thin vacume hose between the intake manifoil and the MAP sensor on top of the fuel filter. 4 mm hose if my memory does not fool me. The old hose tends to get clogged and a new hose can do miracles to the hot start problem.[/QUOTE

Thanks I will look at this first before I do anything else. Would it be ovious that its blocked if I looked into it? Would giving it a clean help or just a new line.

Thanks guys

 

There can be many causes of poor hot starting.
First is slow cranking - check voltage drop between negative battery teminal and engine(can be valve cover for example) - should be around 0.0V. Battery should be as manual say - minimum 107Ah and 800CCA. 1000A gives good kick for hot starting. It simply needs some revs, so the ECU decides to inject fuel. Reputable tuner will modify starting map for better hot starting. Pump wear is the last thing to consider.

 

I was wondering if slow cranking is the issue, I will check my batt to see the cca is written on it and might get a new battery with a higher cca, I've seen one which is 830 cca online.

I was thinking about a tuner but not a clue where to start so have been considering a tuning box.

 

the battery says CCA SAE 590 amps, AH 20h 70 amps


am i right in thinking that this battery even at its best wont be helping my P38 start up, so a higher cca battery will help.

 

It's petrol spec battery - it won't work good with diesel - way too small.

 

That's good to know. I will get a new battery soon and hopefully it will solve the hit start issue.


Thanks guys

 

regarding the battery issue...

wouldn't a bad (or too weak) battery have even more issues at cold start (preheating drains it a bit, cold engine turns heavier than warm one etc)

 

From cold start the glow plugs work and the diesel pump adds more diesel so it starts well from cold every time.

 

Theese engines always start from first turn of crankshaft when cold(with good glow plugs and pump timing set correctly) - even if battery is so weak, that it barely turns over.
Hot start fueling is so lean, that it becomes a problem when it has high mileage - it's designed like that for homologation emission testing - they test emission on hot start - it's ok with new engines only.

 

okay, so why does a low milage car with a weaker battery not have hot start issues, and a car with higher milage does? it's not because of the battery clearly, it's something else, and the symptom (bad hot starting) might get clearer with a bad battery.

some sources on the internet claim it to be stretched timing chains, but mine does it just as bad after I put new chains on and set timing according to the workshopmanual

 

Hi Roger B

It takes less energy from the battery to start a cold engine due to the compression loss in the cylinders (especially a diesel) when the engine is cold.
Cold and thick oil will make it more difficult to turn together with less battery performance when it is cold it may seem that a cold engine is more difficult to start but a hot engine takes much more energy to crank.

Regards

Jos

 

okay, plausible explaination.

but why does a fairly new (low milage) car (with good compression) have less hot start issues (even with battery becomming bad) than a vehicle with more miles (and even with a new battery)?

the hot start issue is clearly related to wear or changes in timing or controlling by the ecu (adaptive setting perhaps??)

 

Thanks everyone, this is my first Range Rover and first diesel so I'm learning new things about it every day, this forum is so helpful. I love the big slow Range Rover even with its faults.

 

If you'd bought a petrol one you still have all the faults but you'd have a big, reasonably fast, Range Rover. And it would have the correct battery.....

 

oh boy, there we go again... dieselfobia
and if you get a petrol it runs 50-70% miles less on a gallon, and depending on where you live a gallon can be 20-40% more expensive..... so you'd be looking at about double fuelcost...... yeah you can run it on gas, does not make it more reliable, takes a lot of space in the boot for a tank, can go even more often to the fuelstation.....

yeah, a V8 is a bit faster, but that teases you to drive it like that too, and then you get fuelconsumptioncost going towards tripple of that a diesel consumes

I can keep up with normal trafic very easy in my DSE, it pulls my 3500kg trailer-with-p38 well enough, and at the pump I fill it up for about 120 Euro max, which gives me another 700-800km of fun.... in my HSE I had to pay about 160 max for a tank of petrol and I'd be back for a refill after about 400-500km.... (to compare... running on gas, reconing a litre of gas is 90% of the energy a litre of pertol contains, it would doe 350-450 km and that would cost about 65 euro.... fuel cost the same a diesel perhaps)

 

Sorry, not dieselfobia at all, each to his own and it was intended as a tongue in cheek comment. I just don't like them even though all of my company cars for the last 20 years have been diesels. I like the sound of a V8, I like the smooth power, I like to be able to hit the sport button, floor the throttle and wonder how the hell you can get something that weighs that much to accelerate that fast. With a diesel, I don't like the rattle, or the driving dynamics. When did anyone ever rev a diesel engine with a big silly grin on their face because of the noise it makes? It's like this years F1 cars, the old V8 with an 18,000 rpm limit sounded gorgeous but the new ones with a V6 and a 15,000 rpm limit just sound wrong. If they had fitted a diesel engine in the P38 that gave the same amount of power as the petrol then I could see the point but it's a heavy car anyway and it needs the extra grunt to make it enjoyable to drive. It may be able to keep up with normal traffic but what about the times when you want to overtake a couple of trucks in convoy?

As for the running costs, i bought my Classic LSE from a friend of a friend. 4.2 litre V8 and already on LPG when he bought it. It had a vertical toroidal tank in the boot on the opposite side to the spare so it looked like there were two spare wheels. It also meant that with the seats folded you still had the full length and had only lost about 250mm of width. It would do around 200 miles on 60 litres of gas so that works out at 15 miles per gallon. But as petrol is twice the price of gas, he was paying the equivalent of 30 miles per gallon. After I bought the LSE he replaced it with a 2.5DSE P38. Compared with the V8 it was gutless, slow and sluggish so he drove it hard all the time and got 25 miles to a gallon of diesel (and diesel in the UK is more expensive than petrol). So it actually cost him more to run and he got less enjoyment out of driving it. Both my P38s are on LPG, in fact, I can't see myself ever driving anything not on LPG. I don't think I could afford to run a P38 on petrol, or not to use it the way I do, I'd constantly be looking at the fuel gauge and would drive it much more gently because I'd be thinking how much it was going to cost me to fill it. Both have toroidal tanks in the spare wheel well so no boot space is lost unless I want to carry a full sized spare which I do when doing long journeys, the rest of the time, I just have a pump in the boot.

 

A couple of comments for those dieselfobes out there.

Diesel engine power can be boosted far more than a petrol engine can. The BMW M51 engine is a good engine and capable of very high mileages. It is very smooth but it is underpowered in its standard form. It puts out only 135 bhp, which is hopeless for a 2.5 tonne vehicle, but with a few mods this can be increased greatly. My own DSE puts out about 190 bhp and more torque than the 4.0L. It is excellent for towing. Torque is what you want for an off roader.

Power could be increased to 250 bhp with a change of turbocharger. This is about the limit of the injector pump. Other BMW cars (not the p38)) with the same engine, back in the day, as it is old hat now, put out considerably more than 250 bhp using a Mercedes mechanical pump.

All this with 26 mpg and running on veg oil that costs 67p/Litre.

Regarding the cold start problems, it is nearly always the timing chain which wears and alters the timing as Rousecapri says. However, over the past few years refineries have been taking sulphur out of diesel to meet emission standards. Sulphur acts as a lubricant for the injection pumps so I guess we can expect more wear problems with the pumps.

 

I'm aware the M51 engine can produce more power, a work colleague has the BMW 525d which uses the same engine and in that variant it is up to something like 170 bhp. I've never been able to understand why, if the engine can produce more power and meet emissions limits when fitted in a saloon car, why is it detuned in the P38? 190 bhp is what my 4.0 V8 should be producing anyway and, as you say, you can get more torque from the diesel which would make it even better for towing which is what I use my car for most. I would still have a problem with the noise it makes but the economy means that I've only got marginally cheaper running costs on LPG than a diesel. Admittedly, you can run veg oil and get it down even lower but that wouldn't work for me. Where do you fill up when you are hundreds of miles from home, McDonalds? I worked it out just recently. My ex-police P38 did 23,000 miles between last years MoT and this. No more than 9,000 of this was done in the UK, the rest in Europe where I can refuel at just about every motorway service area and most supermarkets.

Like I say, each to his own and my objection to diesels is mainly the noise they make, the smell and the fact that you get covered in black stuff as soon as you open the bonnet. However, I do have a thing about the way an engine sounds, I've got 2 V8s, a twin turbo'd V6 and a 4 cylinder bike with a redline at 13,000 rpm and the best thing about all of them is the noise they make.

 

the m51 had to be turned down twice before bmw would allow it to be fitted to the p38. thats why it only produces 130 odd bhp.i cant remember where i read this it might even have been on here. my mate has a chipped 2.5dse and it does go well, but it does have a smoke issue when you boot it. he needs to get the boost turned up a bit to match the extra fueling.

 

I think it was tuned down because bmw were working in there x5 off roader and they didn't want the Range Rover being better then it, not sure how true this is.

I live in central London and the slow speed and pull away suits me great plus I've got a lot of points on my licence so this should keep me out of trouble for a while.

I might get a tuner box put on at some point to help with the mpg and add a few horses but nothing major.

 

It wasn't tuned down - it simply has lower maximum power revs(4400 vs 4800) because of smaller turbo than newer BMW with M51, and this is why it has better down low torque than BMW to suit heavier vehicle. Giving it higher max power rpm would probably end with high emissions on that turbo - it definetely too small for chipped ones. Also notice that AC drive pulley on crankshaft is bigger in RR for better comfort.

 

So could the bigger turbo from the x5 be put on the Range Rover? I'm not that fussed about power just curious

 

Anything could be done - it's just a matter of time and $$.
I think this could be fitted witout problems:
http://shopping.kinugawaturbo.com/k...rbo.com/kinugawabilletturbocartridgeandcoverbmw525325tdse34m51td04-15t50hp.aspx

It has bigger compressor wheel that should cope with ECU chipped to maximum fueling.

 

I have got a Garrett GT2256V turbocharger off a later Range Rover TD6 ready to fit to my DSE. The bolts line up the same as the Mitsubishi turbo so it should be relatively easy to fit. I have also put together a boost controller as the original one is just mechanical.
The Garrett is sized for 180 to 200 bhp so should be in the right range. I want low down boost and the Garrett should give it, as it is variable vane.