m51d25 loses power

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iF ecu thinks the brakes are on ,not with your foot ,faulty switch .OK citroen ,peugeot ect ,They limit acceleration power ,I just throw things in the pot .Didnt say it would taste good ....
 
french cars are designed by loonies, so we can completely forget any similarities between a bmw system and a french one. ;D

however i am very slightly intrigued by this proposal, even if there's absolutely nothing on the internets about anything like this on the TDS. or for the e36 in general. or for any bmw of that era. or ever.
why am i intrigued? the only fault code is for "vehicle speed control" although the car has never had cruise control and doesn't have the correct wiring loom for it either.
my TDS has electronicly controlled throttle and distributor pump. so no cables. usually this means only the switch would need to be installed, if it had the correct wiring loom. mine doesn't, so i would have to splice 3 wires to make it work.
so why do i have a fault code for cruise control? i've no idea. boggles the mind really.

although, bmw people say: no cruise control, ignore the fault code.

edit: the exact fault code is: 20, vehicle speed control, control panel.
 
:oops: first i say how stupid french cars are, and then i eat **** right after...

out of curiosity (ok ok, desperation) i went for a drive and decided to yank out some connectors. just to see what would happen.

after unpluging the intake pressure sensor, fuel heater, EGR solenoid, water temp sensor and the electric fan, the result was: nothing had changed.
it was only after pulling out the crank sensor , did the engine stall. as if it was just turned off. i re-connected it, cranked the engine and it started right up.
only after pulling the MAF connector, did something change. aaand it just lost a bit of low end torque, and the turbo was responding a bit slower. although, now the "mpg gauge" went from 9.5l/100km to 10.5l/100km and i could feel like it definetly had just as much more power... only a bit.
it didn't smoke any more than usual either. (almost no smoke)

what a nice system you got here bmw/bosch! o_O

(replaced parts in bold, all new parts)


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funny thing is, i bought this car thinking: "well diesels of this age were so simple. they must have super simple electronics and can be repaired with communism..."
 
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mazappi said:
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funny thing is, i bought this car thinking: "well diesels of this age were so simple. they must have super simple electronics and can be repaired with communism..."
Click to expand...

I think that's where your going wrong.... you need a mechanic to take a look and not a communist!

Seriously though was the Maf you fitted a cheap one or genuine? if cheap I would try a good one instead.
 
mazappi said:
only after pulling the MAF connector, did something change. aaand it just lost a bit of low end torque, and the turbo was responding a bit slower. although, now the "mpg gauge" went from 9.5l/100km to 10.5l/100km and i could feel like it definetly had just as much more power... only a bit.
Click to expand...

mazappi said:
genuine, very expensive MAF. it was the first part i replaced.
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Click to expand...

Might have been expensive but you must surely wonder why in your words you are getting better mpg and more power with it disconnected?
 
welshsteve said:
Might have been expensive but you must surely wonder why in your words you are getting better mpg and more power with it disconnected?
Click to expand...
no no, not better mpg. i said it was able to consume more fuel = more power when the problem was on. so kinda the opposite of better mpg. maybe i was unclear, so i'll recap.

when the power is cut (the main problem) the fuel consumption gauge goes only up to about 9.5L/100km
after disconnecting the MAF, the consumption can go up to 10.5L/100km.
i.e the engine supposedly gets more fuel when the power is cut, without the MAF. so not better or worse mpg, just able to use more fuel.

it is an mpg gauge on the UK and USA models. for the rest of the world its litres of fuel consumed per 100 kilometres. hence the "mpg gauge" in quotes.

why do i even talk about that gauge? because it's the only indicator of this problem, besides feeling it.

:)
 
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well, here's my final post to this thread.

the car will soon have an m57 diesel engine in it, so i can't be bothered with this issue anymore.
thanks to all who helped!

ps. once i am done with the engine swap, maybe i will post a picture. thanks gb.
 
@mazappi Please let us know what is involved in putting the m57 in, I have heard it can be done but is not straight forward with the electrics, a how to guide would be even better:)
good luck with it.
 
Hi,
I know this thread is old but exactly describes my problem with BMW 525tds (same M51 engine). Its sad that this didn't get resolved. So I will add my experience for future searches.

First of all:
This problem is by 90% faulty fuel-pump

My engine has total of 400 000 km (~250 000 miles). I have older DDE, which is 2.1 (yours is 2.2, means that you had MAF). Mine is M51D25 1994 without MAF so that clearly puts it out of the list of interest.

I will recap what is happening to me:
  • When the engine is cold it does not have power until I rev it at least once over 3000 rpm (I do that only after the water gauge is over mid) or the engine is warm enough
  • When driving with throttle in one position, mostly happens on 5th gear ~2500 rpm (120 km/h) the engine will "fall" into some Safe mode where it does not want to "eat" more than 10 l/100 km (as gauge on dashboard shows)
  • Could be resolved either by holding long enough to pass cca 3000rpm OR lifting foot of the throttle, leave the econometer to drop to 0 l / 100 km and then re-apply throttle
I've already replaced many things such as: turbo, EGR valve, intercooler, all pressure hoses on intake, air temp sensor, control injector (4th injector with wire).
I also cleaned the small filter-net on lift-pump, checked that the lift-pump is fully operational, added small one-way pump between fuel filter & pump.

Tried using some cheap DELPHI diag from eBay (which is mostly okay) and it shows exactly same errors as INPA trough original BMW service (so it is trustworthy) and it said some stuff about the control of injection start.

I was also told by some guy in TDS Facebook group that this behavior is typical for fuel-pump "safe-mode". I will try to replace the pump and then I will update my post accordingly.
 
RaitoCZ said:
Hi,
I know this thread is old but exactly describes my problem with BMW 525tds (same M51 engine). Its sad that this didn't get resolved. So I will add my experience for future searches.

First of all:
This problem is by 90% faulty fuel-pump

My engine has total of 400 000 km (~250 000 miles). I have older DDE, which is 2.1 (yours is 2.2, means that you had MAF). Mine is M51D25 1994 without MAF so that clearly puts it out of the list of interest.

I will recap what is happening to me:
  • When the engine is cold it does not have power until I rev it at least once over 3000 rpm (I do that only after the water gauge is over mid) or the engine is warm enough
  • When driving with throttle in one position, mostly happens on 5th gear ~2500 rpm (120 km/h) the engine will "fall" into some Safe mode where it does not want to "eat" more than 10 l/100 km (as gauge on dashboard shows)
  • Could be resolved either by holding long enough to pass cca 3000rpm OR lifting foot of the throttle, leave the econometer to drop to 0 l / 100 km and then re-apply throttle
I've already replaced many things such as: turbo, EGR valve, intercooler, all pressure hoses on intake, air temp sensor, control injector (4th injector with wire).
I also cleaned the small filter-net on lift-pump, checked that the lift-pump is fully operational, added small one-way pump between fuel filter & pump.

Tried using some cheap DELPHI diag from eBay (which is mostly okay) and it shows exactly same errors as INPA trough original BMW service (so it is trustworthy) and it said some stuff about the control of injection start.

I was also told by some guy in TDS Facebook group that this behavior is typical for fuel-pump "safe-mode". I will try to replace the pump and then I will update my post accordingly.
Click to expand...
If you are talking about a BMW, might be better off on a BMW forum rather than a Range Rover forum. The M51 engine may be similar but the FIP and ECU have differences and your car is nothing like the 2.1 or 2.2 you mention, the M51 in the Range Rover is 2.5 litre.
 
Datatek said:
If you are talking about a BMW, might be better off on a BMW forum rather than a Range Rover forum. The M51 engine may be similar but the FIP and ECU have differences and your car is nothing like the 2.1 or 2.2 you mention, the M51 in the Range Rover is 2.5 litre.
Click to expand...

I'm not talking about the engine displacement, this is same for all M51 engines: 2497cc -> 2.5l.
DDE stands for Digital Diesel Electronics by BOSCH. On M51D25 it is in version 2.1 (1991-1995) and it was updated with M51D25TU to version 2.2 to include MAF (1995-2001). The Range Rover engine is called M51D25M1 but was supplied by BMW to Range Rover in years from 1995 to 2001, thus matching the DDE to be version 2.2 (with explains why it also has MAF).
 
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