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i have plugged my 2.4jtd into fiatecuscan and evrything looks in order but the 'baro pressure' remains pretty much constant at arround 982 +-5mb (nearly atm at sea level) throughout the rev range, am i right in thinking that this measurement is of atmospheric pressure and not manifold absolute pressure? if so what measurement can i check to ensure the map sensor is functioning correctly?
 
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i have plugged my 2.4jtd into fiatecuscan and evrything looks in order but the 'baro pressure' remains pretty much constant at arround 982 +-5mb (nearly atm at sea level) throughout the rev range, am i right in thinking that this measurement is of atmospheric pressure and not manifold absolute pressure? if so what measurement can i check to ensure the map sensor is functioning correctly?
Nope.... maf measures air flow and map measures manifold pressure.

So I suggest your map may be blocked up. back of manifold one bolt little black thing

Take it out and I bet it's all blocked up with sooty grunge. clean with carb cleaner re-fit and measure again. don't leave it too long as the map tells ecu what to do with boost so you could be overboosting.

It should measure close to 1000 at idle or key at mar but nit running and go up with boost
John
 

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baro pressure is atmosphere pressure indeed, ignore that unless you're trying to predict the weather.

you want to be look for something like actual boost pressure and compare it to desired boost pressure.

and, I would take a guess that as you are trying to check it you believe there is a problem or you are experiencing problems.

give us a clue as to what your problem is / symptoms are as well and we can give you better feedback.
 

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cheers artermis, thats what i suspected but could not find any readings for boost etc, i'll look again. i'm just having a nosey really as fiatecuscan was free and got my hands on a cheap cable, my only issue would be the black plum i leave in my wake at high revs and slightly less than average mpg so a bad sensor or boost leak seem likely suspects although there is no audible blowout.
 

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hmm, boost leak is probably favourite.

weak points are top hose near the wing as it bends to come round to inlet, the elbow rubs on the plastic trim although bottom hose is worse as it rubs on gear box.

check the bends in any of the boost hoses. as the pipe expands and shrinks under load it puts real stress on the bends in the pipe.
 

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start your car up and look at turbo charger actuator and you should see it retracting ..get someone to turn engine off and you will see it return back to base point ..if it doesnt ..means you got holes in small bore pipework
 
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Didn't think jtd's had another map sensor so where does it get that reading from? Or is just stored at start up or hard coded?
 
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from its only map sensor:thumbs:
Ok so I thought someone said it was barometric pressure not boost pressure. but is only map not in intake manifold? So it wouldn't be external barometric pressure. unless it takes reading before engine is started or something. or was the one reply mentioning only good for checking weather wrong?
 

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Ok so I thought someone said it was barometric pressure not boost pressure. but is only map not in intake manifold? So it wouldn't be external barometric pressure. unless it takes reading before engine is started or something. or was the one reply mentioning only good for checking weather wrong?
yes it is barametric pressure and remember there is no vacumm in a diesel engine so you dont get negative( no throttle plate to act on as in petrol) ..as soon as you start engine and on tick over ..no boost till turbo develops it:thumbs:
 
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yes it is barametric pressure and remember there is no vacumm in a diesel engine so you dont get negative( no throttle plate to act on as in petrol) ..as soon as you start engine and on tick over ..no boost till turbo develops it:thumbs:
I see, so takes measurement on idle the holds it when on boost? Nice one:thumbs:
 
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it measures atmosperic pressure costantly and any pressure induced in manifold
Ah so the map measures two things? Does it have separate sensors? In the one unit? Just can't understand how it can read atmospheric pressure and boost at same time as only appears to have sensor in intake.
 

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Ah so the map measures two things? Does it have separate sensors? In the one unit? Just can't understand how it can read atmospheric pressure and boost at same time as only appears to have sensor in intake.
no its apressure sensor that measures constantly.if you lift off accelerator it will show atmospheric :thumbs:
 
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