P38A MAF on diesel

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ovalandrover

ovalandrover

Well-Known Member
Posts
1,692
I have a 1999 P38 2.5 BMW diesel and have fueling problems . I also have a NANOCOM but cannot see anywhere to check the MAF.
I have faults logged that cannot be cleared namely
GLOW PLUGS FAULT
TYPE INVALID FAULT LOGGED CURRENT INTERMITTENT
RPM= 28
WATER TEMP=131
OCCURANCE = 14
the car will start from cold and idle at 750 RPM first run of the glow plugs but when revved to 2000 + it will start surging between 2000 and 3 500 dropping back to 2000 and surginging again even when there is no foot on the accelerator pedal . i have ren.ewed the green temp sender on the engine .the crank sensor . no 4 injector . so the next thing i can think of is the MAF but cant find any way to check it with the NANOCOM and dont want to buy a new one if its not going to cure it. i have also had 2 FIP pumps with 2 different timing solenoid on them both pumps have been checked out and timed as per rave . and the best modulation i can get is abot 25 % at idle dropping down to 4 when revved to 2000 then jumping to 60% when surging.
 
ovalandrover said:
I have a 1999 P38 2.5 BMW diesel and have fueling problems . I also have a NANOCOM but cannot see anywhere to check the MAF.
I have faults logged that cannot be cleared namely
GLOW PLUGS FAULT
TYPE INVALID FAULT LOGGED CURRENT INTERMITTENT
RPM= 28
WATER TEMP=131
OCCURANCE = 14
the car will start from cold and idle at 750 RPM first run of the glow plugs but when revved to 2000 + it will start surging between 2000 and 3 500 dropping back to 2000 and surginging again even when there is no foot on the accelerator pedal . i have ren.ewed the green temp sender on the engine .the crank sensor . no 4 injector . so the next thing i can think of is the MAF but cant find any way to check it with the NANOCOM and dont want to buy a new one if its not going to cure it. i have also had 2 FIP pumps with 2 different timing solenoid on them both pumps have been checked out and timed as per rave . and the best modulation i can get is abot 25 % at idle dropping down to 4 when revved to 2000 then jumping to 60% when surging.
Click to expand...
Unplug the MAF and run it. If the MAF is faulty you will notice a difference straight away. It defaults to saved settings. Bit sluggish when cold but runs fine once warmed up.
Be careful of the cheap chinesium copies if you buy a new one
 
Rubberknees said:
Unplug the MAF and run it. If the MAF is faulty you will notice a difference straight away. It defaults to saved settings. Bit sluggish when cold but runs fine once warmed up.
Be careful of the cheap chinesium copies
Click to expand...
tried that still the same
also engine light comes on when surging
 
ovalandrover said:
I have a 1999 P38 2.5 BMW diesel and have fueling problems . I also have a NANOCOM but cannot see anywhere to check the MAF.
I have faults logged that cannot be cleared namely
GLOW PLUGS FAULT
TYPE INVALID FAULT LOGGED CURRENT INTERMITTENT
RPM= 28
WATER TEMP=131
OCCURANCE = 14
the car will start from cold and idle at 750 RPM first run of the glow plugs but when revved to 2000 + it will start surging between 2000 and 3 500 dropping back to 2000 and surginging again even when there is no foot on the accelerator pedal . i have ren.ewed the green temp sender on the engine .the crank sensor . no 4 injector . so the next thing i can think of is the MAF but cant find any way to check it with the NANOCOM and dont want to buy a new one if its not going to cure it. i have also had 2 FIP pumps with 2 different timing solenoid on them both pumps have been checked out and timed as per rave . and the best modulation i can get is abot 25 % at idle dropping down to 4 when revved to 2000 then jumping to 60% when surging.
Click to expand...
Have you sorted the 60C EDC temperature? The fact that you have replaced the green sensor means nothing with the quality of parts these days. If the modulation is 25% at idle with the engine hot there is something seriously amiss. None of those figures make sense, rpm 28? Water temp 131? Neither are likely to be correct, check the earth from engine to chassis
 
Datatek said:
You can check the MAP sensor with Nanacom
Click to expand...
May i ask how?
Datatek said:
Have you sorted the 60C EDC temperature? The fact that you have replaced the green sensor means nothing with the quality of parts these days. If the modulation is 25% at idle with the engine hot there is something seriously amiss. None of those figures make sense, rpm 28? Water temp 131? Neither are likely to be correct, check the earth from engine to chassis
Click to expand...
I have just put a brand new one in thats the third one and thats the fault readings i get and when cleared they come strat back so it dosent make sense. the earth wires are all good and the engine starts first turn over . and no they sent me the wrong sensor for the one at the front. and reading the manual from NANACOM the modulation should be between 45% and 55%and not varie more that 2 % at any speed once the engine is warm
 
ovalandrover said:
May i ask how?

I have just put a brand new one in thats the third one and thats the fault readings i get and when cleared they come strat back so it dosent make sense. the earth wires are all good and the engine starts first turn over . and no they sent me the wrong sensor for the one at the front. and reading the manual from NANACOM the modulation should be between 45% and 55%and not varie more that 2 % at any speed once the engine is warm
Click to expand...
One of the EDC screens in the Nanocom (I don't have Nanocom so cannot be explicit) will show manifold pressure, If the car is an auto, in gear left foot on the brake, briefly rev the engine and watch the pressure rise.
The fault readings are nonsense re revs and water temperature so all readings are likely to be suspect IMO. Have you checked the OBD connector for corrosion?
Correct, the modulation should be 50% +/- 5% but that is at idle with an engine temperature of 95C, the modulation varies considerably with engine temperature.
 
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