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rover_400_95_99
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Discussion Starter · #1 · (Edited)
Everyone goes on about how much the maf sensor effects the running of the L series engine when fitted in an R25/45 etc but as we generally know that in the R200/400's this is not so as all it tends to do is control the EGR valve etc.

My question is how much of a part does the MAP sensor which detects the boost pressure in the manifold and the amibent air pressure play in the running of the engine.

The reason i'm asking is :-

How reliable are they?

How do you know if they are faultly or failed?

Can they be tested to see if they are working correctly?

Finally can the MAP unit effect you tick over speed?

As mine seem to be hanging up at a 1000 rpm before settling to a normal tickover even with the Ron's TU1 unit turned to zero in both dials please note this was happening before i installed my hybrid i have changed the maf unit for a spare i had off my 200 and been through just about ever other option bar replacing the injection pump/ECU or MAP sensor all of which i can do as i have spares of all of them just trying to possibly eliminate the easiest to change first!

Any input welcome...

Cheers, Mark.
 

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sounds quite normal to me, when in traffic and coming to a stop my engine stays at a shade over 1000rpm until i take my foot off the brake, or wait for a while.
 

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Sounds normal to me too. When travelling at speed select neutral and release the clutch then observe the idle speed. It rises and falls on mine, but on others it hangs at a high-ish level of around 1krpm. This I think is to provide enough vacuum to make the brakes work properly!

If the MAP sensor goes faulty then you'll know about it on a 200/400/600 as the ECU light will come on and the car will be drive really badly as if without a turbo. Try unplugging the MAP line and taking it for a drive, you'll see what I mean!.
The MAP sensor is the main way that the fuelling when on boost so when it goes wrong you'll know about it.
 

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other_manufacturer
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Many diesels do not return to idle mode fully until the speed sensor tells the ecu that you've stopped. Its like the old anti-stall devices fitted to mechanical pumps.

This was the case on my 45, 75 and is true of my X-type as well.

The easieist way to test the map sensor is to measure its signal and refer to the chart on my website.
With the engine stopped it reads atmospheric pressure which is about 1.8volts.
I doubt the signal has much effect with your foot off the pedal as the ecu will be in idle mode anyway.

Ron
 
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