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1995-2002 Range Rover P38A
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Discussion Starter #1
Hi,
My car without visible smoking failed the emission test. Here diesels are tested only for k<=8, an opaqueness test in exhaust gas. The isssue I guess is that testers speed the engine beyond 5000 RPM & at that instant a puff of smoke is seen. Normally, even in the highway I don't go upto that RPM, max I go is around 4000 RPM. Since the car is chipped it allows higher amount of diesel in high engine speeds. I have another 14 days to show them the car again, if not I can't get the road licence.

My question is how am I to reduce IQ(injection quantity) levels on this enginee? (without changing the chip)

If I remove the MAP sensor supply line(air or power) will it help?

In my TOYOTA of course it's matter of rotating a screw to reducee the IQ.

But this BMW M51 injection pump has no adjustment screws. For that matter it has none at all.

Any quick advise is appreciated.

thanks

kapila

p.s. new air filter added yesterday.
 

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1995-2002 Range Rover P38A
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Kapila, 5000 rpm sounds very high for the M51 diesel. I would not like to run my engine at that speed.

Can you check the test procedure to make sure the testers are doing it correctly?

A lot of larger, older diesel engines won't do 5000 rpm. I had a classic with a Perkins 4326 3.8L engine and it only rev'd to 2800 rpm. Maybe they are applying new, modern car, standards where diesel engines rev faster.

Leaving the air filter off or fitting a new one may do the trick. Not sure about disconnecting the MAF pipe.

You could revert to the original chip if you either have two ECU's or have fitted the chip in a ZIF socket.
 

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1995-2002 Range Rover P38A
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690 Posts
Screw a block of wood to the back of the pedal? ;-)
 

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1995-2002 Range Rover P38A
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if you pull the map pipe,the engine will not add extra fuel ,so the engine will be running leaner than it should as it will be getting turbo boost,but not the extra fuel for it. pull the pipe and go for a drive ,it will be gutless :)
 

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5000 rpm is the max speed for the BMW M51, which is indeed quite high. Normally fuelling will be limited and eventually cut when approaching 5000 rpm. In your case the culprit is obviously the chip.
You can trick the ECU into running leaner by pulling the airline from the intake manifold to the MAP-sensor. It will make the car very sluggish to drive, but the effect when revving without load will be less, because without load you will never reach full boost.

BTW, the test is very similar to that in Bhellgium, basically just torturing the engine. To make matters worse, when always driven gently (which I'm sure is not the case with you) some carbon will accumulate in the exhaust, only to be blown clear when revved excessively during the test, and thus failing. Hence the popular and accurate advice to drive in too low a gear just prior to testing, in an attempt to clear everything.

Filip
 

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i used to have to pull the pipe on a ford focus to get through it's mot. had the test done as normal and it failed,pulled the pipe and the difference it made was very big. ;)
 

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1995-2002 Range Rover P38A
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Discussion Starter #7
Thanks guys.
As I've already changed the air filter , let me try again with the MAP pipe reemoved. after removing do I have to cover the manifold side of the line?

Anyway, wish me luck.

rgds

kapila
 

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1995-2002 Range Rover P38A
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the 5000rpm you talk of is not how the test is carried out, all the MOT tester does is rev the engine to the limiter and release the pedal immediately, so if your engine maxes out at 2800 then thats all the engine will be revved to. Not the best test in the world, but my advise is to drive the car before the mot test time and get it really hot and accelerate hard in second or third a few times to clear the built up soot in the exhaust, by the way poodling a modernish diesel engine all the time and just town driving does it no good at all, causes soot build up in the exhaust and will cause the egr valve to malfunction and clog up so a good high rpm run now and again does it the world of good. Also don't block off the egr valve as some people do, because the valve reduces the temp of the combustion chamber and helps the engine and injector tips live longer and will alter the emissions, just a tip.
 

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Good point Gilbertd, noted:thumb:
 
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in the netherlands it is not done like you wrote...

the engine is hooked up to a testinggear
it's details are fed into the tester
it is kept running idle untill the tester says to give full throttle
the mechanic should give full throttle
the tester reads rpm, how fast it gets to its max RPM etc
then the tester says the mechanic should let go of the throttle
the engine is let run idle for a minute or so
the test repeats three times minimum.

The engine should reach within a small margin its factory set max engine revs (so not only 2800 if factory settings should be 4800 or so) It should reach that rpm within 1 or 2 sec. (slowly depressing the throttle would reduce the amount of fuel and thus the amount of smoke) and the max rpm is to be held for 2 or 3 sec or so before the tester orders to let go of the throttle...
 

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1995-2002 Range Rover P38A
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Discussion Starter #13
They fit a temp probe into the dipstick tube & a smoke probe into the exhaust.
Reviving the car is by the techs & we are not allowed to do that. They tested for 3 times and the report given indicated respective RPM as 4800, 5200 & 5150. Results were 8,9 & 17 (k factor) which is supposed to be less than 8.

rgds
 

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1995-2002 Range Rover P38A
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But the 2.5 DSE only revs to 4,500 rpm red line anyway? So how are they getting it up to over 5,000, the rev limiter should cut in?
 

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No it doesn't, the M51 has a full load redline of 4400rpm after which fuel cut-off starts, but no load (or low load) max speed is 4950 +/- 150rpm.
I have seen mine reach 5000rpm once in an emergency.
 

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Discussion Starter #16
Passed it, guys.
New a/filter & MAP tube removed from manifold, got it through.
:dance:
thanks to all:thumb:
 
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