EntropyUK

Well-Known Member
I know this subject has been discussed at length but I couldn't find a how to test guide for the MAP sensor. My diesel is a little sluggish in the acceleration department and Wammers recommended checking it as a starting point. I took the hose off and it looks fairly clean with only a little oil on it (not gunned up like some photos on the net). So everything looks like it should be working but need to be sure, how do you test as I don't want to fork out £50 just in case.
 
I know this subject has been discussed at length but I couldn't find a how to test guide for the MAP sensor. My diesel is a little sluggish in the acceleration department and Wammers recommended checking it as a starting point. I took the hose off and it looks fairly clean with only a little oil on it (not gunned up like some photos on the net). So everything looks like it should be working but need to be sure, how do you test as I don't want to fork out £50 just in case.
Whilst it is nice to be confused with a knowledge genius like @wammers .....

It was I who mentioned the MAP in your previous thread :D:D:D
 
So yesterday as a quick try I took the house off the Map Sensor and did the 0-60 test with no charge in times. Now going to see if the sensor is outputting a voltage when running. Could I do any damage by putting a small screw driver into the intake manifold connection to check its clear as the pipe was clear with no signs of splitting.
 
So yesterday as a quick try I took the house off the Map Sensor and did the 0-60 test with no charge in times. Now going to see if the sensor is outputting a voltage when running. Could I do any damage by putting a small screw driver into the intake manifold connection to check its clear as the pipe was clear with no signs of splitting.

Should be about 5 volts to sensor with ignition on engine running. This will vary as pressure is increased signaling the ECU of pressure change. Make sure there are no obstructions in the pressure pipe and that it is not split or leaking. Remove MAP sensor and use some contact cleaner and a gentle blow from an air line to clean out any gunge that maybe blocking it. Do this several times until all oil and gunge is gone. DO NOT poke anything inside it. If after that and all is apparently sound there is no change in 0 to 60 time with MAP connected/disconnected, change MAP sensor. Intercooler should be flushed ever 48,000 miles. Better to clear manifold pip with an airline. But a suitable probe used carefully should not do any harm.
 
Will the sensor put out 0v at tick over? Just put a wire out from the middle connection on the sensor connector and it didn't register any voltage. Unfortunately no one around to rev the engine for me.
 
Will the sensor put out 0v at tick over? Just put a wire out from the middle connection on the sensor connector and it didn't register any voltage. Unfortunately no one around to rev the engine for me.
Pins 2 and 3 should be the power supply and pin 1 the signal.
 
As a caveate I acknowlegde your wisom but the middle wire is green indicating the siganl wire from what I have read . This backs up some of the map sensors offering the sensor with a pin out diagram.

Looking at the connector from where the wires enters it. Is it 123 or 321? Don't want test the +ve and think all is OK.
 
As a caveate I acknowlegde your wisom but the middle wire is green indicating the siganl wire from what I have read . This backs up some of the map sensors offering the sensor with a pin out diagram.

Looking at the connector from where the wires enters it. Is it 123 or 321? Don't want test the +ve and think all is OK.

Pin 1 is Blue/Yellow. Pin 2 is Brown/Green. Pin 3 is White. Pins 2 and 3 are the circuit through the sensor. Pin1 the variable signal. Look at RAVE diagrams.
 
Its not the map sensor causing the poor performance as I am getting 2v drooping to about 1v occasionally.

I might take you up on that GRRR as I am in Tring. Also would be good to get a 121 with a Nanocom system.

However I did see air bubbles running through the fuel line so could that be the cause of 24 sec 0 - 60 performance?
 
Don't like the sound of air bubbles. Did you do Wammers lift pump test? Or check fuel filter housing isn't cracked. Or fuel filter is fine.

Would this evening be OK? Just about to take my lad out for the afternoon.
 

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