P38 Paul Posted September 14, 2014 Share Posted September 14, 2014 hello peoples , I have owned my car since 2006 but got a problem that I need help with , its a p38 diesel m/y 2000 that has lost power . it went faulty on the M5 at 80 mph , it shuddered just like a misfire & then picked back up again , 5 minutes later in the fast lane it did it again then lost power , there were no messages on the dashboard so I drove it home 100 miles with mixed acceleration , sometimes full power but most of it reduced power . took it to an independent L/R dealer who plugged it in & said it was the injection pump , he changed the pump but on picking it up it had the same problem so I went back & he plugged it back in again & said there was no fault showing , he test drove the car & it drove without fault & said that these engines like to be revved but I said that it would never drive it as hard as he did . so he suggested that the in tank fuel pump maybe a little worn , so this weekend I changed the pump but to no avail . I still have to take a run at a hill & take my life in my hands at busy junctions because there is no get up & go . I have spent over a grand in one week & still don't know what is wrong with the car . anyone got any ideas on what is wrong or any suggestions ? Quote Link to comment Share on other sites More sharing options...
elbekko Posted September 14, 2014 Share Posted September 14, 2014 Could be the turbo pressure sensor or the hose going to it. Quote Link to comment Share on other sites More sharing options...
steve b Posted September 14, 2014 Share Posted September 14, 2014 Assuming the rubber pipes from turbo to engine are all ok and not split/delaminated inside so you have full air flow and boost , I'd look at the mass air sensor on the side of the fuel filter . try washing it out with a bit of brake cleaner and make sure the pipe is clear and the electric plug is good cheers Steveb Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted September 14, 2014 Share Posted September 14, 2014 it went faulty on the M5 at 80 mph , it shuddered just like a misfire & then picked back up again , 5 minutes later in the fast lane it did it again This makes me think of a build up of water in the fuel filter. Under high fuel flow conditions, water is drawn from the filter separator and when 'burnt' produces an 'engine miss' sensation. Have you drained or changed the fuel filter? HTH Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 14, 2014 Author Share Posted September 14, 2014 hello David , the fuel filter was changed in April of this year & with the mileage it has done in the past month I would have thought there was very little chance of any water there might of been in the system at present , do you think I ought to change the filter again ? kind regards , Paul . Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 17, 2014 Author Share Posted September 17, 2014 hello chaps , just a quick update , I have changed the fuel filter again & checked the rubber pipes from the engine to turbo . can you tell me where to look for the turbo pressure sensor ? Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 17, 2014 Author Share Posted September 17, 2014 MAF , is that on the side of the fuel filter or air filter ? Quote Link to comment Share on other sites More sharing options...
steve b Posted September 17, 2014 Share Posted September 17, 2014 ........post #3 Steveb Quote Link to comment Share on other sites More sharing options...
elbekko Posted September 18, 2014 Share Posted September 18, 2014 hello chaps , just a quick update , I have changed the fuel filter again & checked the rubber pipes from the engine to turbo . can you tell me where to look for the turbo pressure sensor ? If I recall correctly, it's on/near the right shock tower. Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted September 18, 2014 Share Posted September 18, 2014 There are two bits of kit being mentioned here, they are NOT co-located, and people are confusing either the items or their locations. So: The boost pressure sensor is mounted to the same bracketry that holds the fuel filter. The MAF is bolted to the outlet of the air filter box. Apologies, I didn't respond to your post of 14th because I didn't see it at the time. It doesn't help now, but I would have just drained 'some' fluid from the sedimenter under the filter, as that is where water is collected. I did this once when partway through a trip, which meant I could directly test the results on the rest of that leg, and again on the return leg. For the future, unless you have very strong fingers, it's likely you will need a pair of pliers, or similar, to release the drain plug in the sedimenter. HTH Quote Link to comment Share on other sites More sharing options...
qwakers Posted September 18, 2014 Share Posted September 18, 2014 or in my case the head will sheer of the drain plug and then you're stuffed in other words i wouldnt do it for the 1st time out on the road just in case... Quote Link to comment Share on other sites More sharing options...
steve b Posted September 18, 2014 Share Posted September 18, 2014 you are quite right there David , my apologies for miss - naming the sensor , but the fix/check is still worth doing as when the boost pressure sensor fails to read, the ECU/FIP go into a sort of medium limp mode - struggling to get to 70mph and slow accel. they are expensive little blighters so a quick clean and check is worth it , also worth plugging it in to a scanner as these faults should show as different codes cheers Steveb Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 20, 2014 Author Share Posted September 20, 2014 hello Steve , there were no codes coming up on the scanner , only a knackered FIP . but your description of a medium limp home mode with slow acceleration couldn't be more accurate , is there any way of checking the boost pressure sensor " apart from cleaning it first " before buying a new one . cheers Paul . Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 20, 2014 Author Share Posted September 20, 2014 hello David , thanks for the new sensor locations , I thought I was cracking up when I couldn't find them , regards , Paul . Quote Link to comment Share on other sites More sharing options...
steve b Posted September 20, 2014 Share Posted September 20, 2014 Have you plugged it in recently ? On my mates Snapon reader it showed boost pressure fault in the log , on this particular one on closer examination it turned out to have a cracked pipe stub on the sensor which I was able to re-attach using chemical metal . I was lucky enough to be able to borrow a known good one to prove it was wrong before hand . This all came to light after fitting a Bosch service exchange FIP as someone had been in the old pump and fitted incorrect parts which were somehow masking the failed boost pressure sensor . I'd try and find a decent s/h sensor as the price new is around £100 or a loan one to prove it's kaput It transformed the whole driving experience when working correctly cheers Steveb Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 21, 2014 Author Share Posted September 21, 2014 hello Steve , I have no fault reader but what I have just done is took it for a short drive & about two miles from home I unplugged the sensor & took the pipe off , this made no difference whatsoever to the carp running of the engine but it did burst into life at one stage for about 100 yards & then went back to carp running , but it does that when its all plugged in . so plugged in or disconnected its still runs the same . is the sensor faulty ? what do you think Steve ? regards , Paul . Quote Link to comment Share on other sites More sharing options...
steve b Posted September 21, 2014 Share Posted September 21, 2014 Hi Paul if it's still doing the same including occasional full power it sounds more like either fuel delivery or the mass air sensor near air filter . Is the tank pump a bit noisy? Pop the cap off and get someone to turn the ignition on while you listen at filler neck , it is audible but shouldn't sound rough and/or noisy . cheers Steveb Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted September 21, 2014 Author Share Posted September 21, 2014 hello Steve , in tank fuel pump is new last week , is there anything I can check or clean on the MAS , or is it replacement only ? do you think I can rule out the MAP sensor ? thanks for sticking with me on this , regards , Paul . Quote Link to comment Share on other sites More sharing options...
steve b Posted September 21, 2014 Share Posted September 21, 2014 without plugging it in to get fail codes it's hard to say replace for sure , I'm sure there are resistance values across the terminals but I don't know what they should be - someone here might though . Otherwise all you can do is check the condition of the terminals on the sensor and the plug and maybe clean the sensor itself with brake cleaner cheers Steveb Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted October 22, 2014 Author Share Posted October 22, 2014 Hello chaps , just a quick update on the loss of power I had on my P38 , in the end it turned out to be the mass air flow meter , this I found after replacing the EGR valve & the boost pressure sensor , all of these showed up as faulty when plugged in to a fault code reader but in reality it was just the MAF sensor , adding the cost of a reconditioned FIP & a new in tank fuel pump this bloody car has cost me just over £1250 in 6 weeks . thanks to everyone that posted there ideas , I couldn't have found this fault without you guys . Quote Link to comment Share on other sites More sharing options...
steve b Posted October 22, 2014 Share Posted October 22, 2014 good to hear Paul , it is frustrating with the P38 diagnostic's , some faults don't really show too well ....am in the middle of one that has several faults up on the dash that now looks like a leaking windscreen seal / damp drivers side carpet / damp BECM wiring/unit ..It's all a challenge cheers Steveb Quote Link to comment Share on other sites More sharing options...
Escape Posted October 23, 2014 Share Posted October 23, 2014 Hello chaps , just a quick update on the loss of power I had on my P38 , in the end it turned out to be the mass air flow meter , this I found after replacing the EGR valve & the boost pressure sensor , all of these showed up as faulty when plugged in to a fault code reader but in reality it was just the MAF sensor , adding the cost of a reconditioned FIP & a new in tank fuel pump this bloody car has cost me just over £1250 in 6 weeks . thanks to everyone that posted there ideas , I couldn't have found this fault without you guys . Glad you got it solved in the end, and thanks for the feedback. I'd even say that the cost is quite reasonable, considering the parts changed and not doing it yourself. The danger with diagnostics is they often point to a faulty sensor that is actually a result of some other problem. Rather than changing the sensor I always try to monitor live data to see it is indeed working and if values reported are normal. Still, not too bad and the new FIP should last a good while and save you from hot start issues etc that are common when the FIP wears out. Filip Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted October 24, 2014 Author Share Posted October 24, 2014 hello Steve , if my BECM goes faulty like yours I am going to buy a 50p service kit " a box of matches " & have it as the center piece on November 5th LOL . Quote Link to comment Share on other sites More sharing options...
P38 Paul Posted October 24, 2014 Author Share Posted October 24, 2014 hello Filip , thanks for your input & would like to say that I did do most of the work myself apart from the FIP & the diagnostics as I find that the P38 is a real nice car to work on . regards Paul . Quote Link to comment Share on other sites More sharing options...
wildeone2 Posted October 27, 2014 Share Posted October 27, 2014 had this happen to mine take air filter out and clean it or replace mines a kn one the filter was blocked causing the top intercooler hose to collapse intermittently, no power ect worth a try Quote Link to comment Share on other sites More sharing options...
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