P38 2.5 dhse - strange starting issue only every 3 starts

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J

Jamieae

Member
Posts
11
Location
Romsey, Hampshire (Southampton)
Hi guys. I have just joined the forum, hoping for some help. I have searched forums and online and gathered lots of information but my problem still persists. Here’s a brief rundown.

it’s a 2000 p38 2.5dhse (m51 bmw diesel engine)

The scenario is i go start it and the glow plug light comes on and then after 10-15secs goes out, I’ll then crank the engine and it’ll start fine but have a high idle (around 2000rpm I’d guess) and the rev counter won’t work.

I will then turn it off and go to start it again and the glow plug light won’t come on and it’ll start as normal (normal idle and rev counter working) but will have a gearbox fault message on the dash.

I then turn it off and start again (with no glow plug light on dash again) and it’ll start, idle and rev counter all ok and without the gbox fault.

I can then drive it like normal but when I go to start it again it’ll do the some thing as before. High idle first start, normal idle gbox warning second start, all good third start.

before I get told off and to search I have checked and or replaced the following

- Crank sensor x 2 (one new one and one tested used one, just incase the new one was faulty out the box)
- in tank fuel pump
- glow plugs (Bosch ones)
- glow plug relay - genuine tested used one
- maf sensor - gen. tested used
- map sensor - gen. tested used
- all vacuum lines replaced
- all boost hoses replaced
- ecu coolant temp sensor (green one on head)
- new Bosch battery
- injector leak off pipes

I’ve checked the following

- 150ml ish of fuel delivered to the high pressure fuel pump in 15seconds (only when glow plug light comes on is this correct)
- 12volts at all the glow plugs when glow plug light comes on dash
- alternator gives 13.7volts when engine is running
- cleaned and checked all plugs going to sensors, high pressure pump, etc checked for broken wires/insulation etc.


there’s probably more that I’ve forgotten but you can see I’ve had a go at the usual suspects but the problem is unchanged.

the only thing of note I can think of is that it has an end tuning chip fitted to the ecu. This was fitted well before this issue started.

if anyone has had this issue before or knows of someone that could have a look at it locally (Hampshire/Wiltshire based) and help/ideas will be much appreciated.

I’m getting close to plugging the plug on it so on another note if anyone wants a 3 owner 138k p38 with the above issue please get in touch as unfortunately think the only way forward would be to break it for parts which would be a shame but can’t see someone wanting to buy it as it is.

once again any help would be much appreciated.

many thanks Jamie
 
Jamieae said:
Hi guys. I have just joined the forum, hoping for some help. I have searched forums and online and gathered lots of information but my problem still persists. Here’s a brief rundown.

it’s a 2000 p38 2.5dhse (m51 bmw diesel engine)

The scenario is i go start it and the glow plug light comes on and then after 10-15secs goes out, I’ll then crank the engine and it’ll start fine but have a high idle (around 2000rpm I’d guess) and the rev counter won’t work.

I will then turn it off and go to start it again and the glow plug light won’t come on and it’ll start as normal (normal idle and rev counter working) but will have a gearbox fault message on the dash.

I then turn it off and start again (with no glow plug light on dash again) and it’ll start, idle and rev counter all ok and without the gbox fault.

I can then drive it like normal but when I go to start it again it’ll do the some thing as before. High idle first start, normal idle gbox warning second start, all good third start.

before I get told off and to search I have checked and or replaced the following

- Crank sensor x 2 (one new one and one tested used one, just incase the new one was faulty out the box)
- in tank fuel pump
- glow plugs (Bosch ones)
- glow plug relay - genuine tested used one
- maf sensor - gen. tested used
- map sensor - gen. tested used
- all vacuum lines replaced
- all boost hoses replaced
- ecu coolant temp sensor (green one on head)
- new Bosch battery
- injector leak off pipes

I’ve checked the following

- 150ml ish of fuel delivered to the high pressure fuel pump in 15seconds (only when glow plug light comes on is this correct)
- 12volts at all the glow plugs when glow plug light comes on dash
- alternator gives 13.7volts when engine is running
- cleaned and checked all plugs going to sensors, high pressure pump, etc checked for broken wires/insulation etc.


there’s probably more that I’ve forgotten but you can see I’ve had a go at the usual suspects but the problem is unchanged.

the only thing of note I can think of is that it has an end tuning chip fitted to the ecu. This was fitted well before this issue started.

if anyone has had this issue before or knows of someone that could have a look at it locally (Hampshire/Wiltshire based) and help/ideas will be much appreciated.

I’m getting close to plugging the plug on it so on another note if anyone wants a 3 owner 138k p38 with the above issue please get in touch as unfortunately think the only way forward would be to break it for parts which would be a shame but can’t see someone wanting to buy it as it is.

once again any help would be much appreciated.

many thanks Jamie
Click to expand...
Gearbox fault suggests that the battery voltage may be low, that would be my first check. Should have at least 12.6 volts before starting and no less than 11.4 with the glow plug lamp on.
 
+1 on battery and this cold weather wont help
unfortunately 13.7 isnt enough to maintain long term battery health, ideally the regulator needs upgrading to 14.7v. not hard or expensive (on the petrol version) and worth every penny
 
kermit_rr said:
+1 on battery and this cold weather wont help
unfortunately 13.7 isnt enough to maintain long term battery health, ideally the regulator needs upgrading to 14.7v. not hard or expensive (on the petrol version) and worth every penny
Click to expand...
Easy to upgrade the diesel regulator too with the following regulator:-
Mobiletron VR-VW010 i
About £15
 
Thanks for the replies chaps. I’ll recheck the voltage when running and also before starting/glow plugs on etc tomorrow. Looks like the regulator upgrade is the way forward to rule out another possible cause. It’s just funny how it repeats the same sequence every three starts even after a long drive or if you do it in a row without even moving the car.

would the crank sensor cause a constant fault or do they come and go as it were. I know the starting every three times would probably rule the crank sensor being bad out as guess it would either be sporadic or fail completely?!?

Once again thanks for your help/suggestions so far. Jamie
 
Some cars, i don't know about the diesel p38, need a certain number of start cycles (often 3) to make a fault permanent or to clear it. Maybe that's what's happening. Don't know
 
Jamieae said:
Thanks for the replies chaps. I’ll recheck the voltage when running and also before starting/glow plugs on etc tomorrow. Looks like the regulator upgrade is the way forward to rule out another possible cause. It’s just funny how it repeats the same sequence every three starts even after a long drive or if you do it in a row without even moving the car.

would the crank sensor cause a constant fault or do they come and go as it were. I know the starting every three times would probably rule the crank sensor being bad out as guess it would either be sporadic or fail completely?!?

Once again thanks for your help/suggestions so far. Jamie
Click to expand...

Tend to come and go before they fail completely. Usually when hot. Might be worth checking diag for #4 timing. I think it runs on default values when that fails.

I don't think the later diesel uses the temperature sensor as it takes the air volume off the MAF. I wonder of it if it might affect the start fuelling though?
 
Grrrrrr said:
Tend to come and go before they fail completely. Usually when hot. Might be worth checking diag for #4 timing. I think it runs on default values when that fails.

I don't think the later diesel uses the temperature sensor as it takes the air volume off the MAF. I wonder of it if it might affect the start fuelling though?
Click to expand...
They start just as well with the MAF disconnected using the block temperature sensor and defaults.
 
Update - Hi. Sorry for the delay getting back with an update. Been rather busy with work etc.

I have replaced the regulator with the one recommended (thanks datatek)

I then checked the voltages and they were as follows

Battery (With Key Off) - 12.58v
Key On & Glowplug Light On - 11.57v
Key On After Glowplugs light goes out - 12.13v
Started/ Engine Running - 14.36v

I Noticed the Alternator Seemed Quite Original Looking So Not Sure If It’s Worth Replacing That and swapping the new regulator over onto it?

It is still doing the same starting problem/process as I described above.

The only thing I’ve noticed is it will only rev up/high idle if and when the glowplug comes on.

If the light doesn’t come on I know it’ll start without the fault.

Not sure if it could be down to a faulty glowplug relay/module?

I have also ordered a hankook 1000ah battery that people seem to recommend just to rule out the battery. As I’m not sure what the voltage drop is while cranking.

Could also the starter be taking/needing too much power if it’s old? (It starts fine, just looks quite original like the alternator) Kind of running lout of things to replace at this point. I think the high pressure pump, 4th injector, starter and alternator are pretty much all I’m left to replace.

Once again thanks for all the help and advice so far and any more ideas/advice would be very much appreciated.

Thanks Jamie
 
The battery voltages look pretty normal, no need to swap the alternator. High idle is normal when the engine is cold. It might be worth looking at the engine temperature sensor for the ECU and crank sensor on diagnostics.
Starter motor also sounds OK but listen to see if cranking sometimes seems slower than normal.
 
Update - I have now purchased a nano com to try and get to the bottom of this fault as even after speaking to several p38/Land Rover specialists/garages they all seem to say replace this/that which i have already done.

The readings were as follows.

(These were after driving the car so not completely cold temps etc)

Below are before starting/not running but when the glowplug light comes on and it had the starting issue

water temp - 134.52
Air temp - 84.19
Boost pressure - 251.27
Ambient pressure - 84.13
Throttle pot % - 0.00
Throttle pot V - 0.4
Battery - 12.04v
Low idle - 0.00
Cruise Status - Accel. Res

Below is as above not running but when it will start idle and drive as it should.

water temp - 97.80
Air temp - -38.88
Boost pressure - 105.74
Ambient pressure - 105.74
Throttle pot % - 0.00
Throttle pot V - 0.4
Battery - 12.22
Low idle - 750.75
Cruise Status - Cruise off

Both these readings are back to back so within seconds/minutes of each other.

as you can see when I have the issue as stated in the first post most of the sensors are reading high/wrong.

also the cruise control status is different.

Would this point to an ecu fault?

or any other ideas/suggestions?

I would like to get to the bottom of this but if not if anyone reading this is interested in a 2 owner 134k dhse with lots of history & good options (full wood interior & rear picnic tables etc) with many new parts such as air suspension&shocks, tyres, brakes, hoses etc please get in contact as I will probably pull it apart as many buyers won’t understand the “turn the key on & off three times if the glowplug light comes on issue”
 
Looking at the voltage the battery is dead 12.4v is dead 12,2v is even worse at those readings it will drop very low as you crank and cause all sort of mischief, mf31 1000 battery is what you need under £100 delivered from batterymegastore
 
brianp38dse said:
Looking at the voltage the battery is dead 12.4v is dead 12,2v is even worse at those readings it will drop very low as you crank and cause all sort of mischief, mf31 1000 battery is what you need under £100 delivered from batterymegastore
Click to expand...

Hi. I have just fitted a brand new hankook 1000ah battery. The voltages from the nanocom readings are with the ignition on not running. I would assume the new battery isn’t dead out of the box? What should a good battery read? I have also changed the regulator for the uprated one as suggested further up in this thread. I see 14.3volts when running. I have also had a running car connected via jump leads incase the voltage drop was the issue and I still get the starting/revving issue.

Not sure if any of this extra info helps. Thanks Jamie
 
A good battery fully charged should read 12.8v, did you fully charge the new one before fitting as that is advisable as they may have been sitting on the shelf for some time.
 
brianp38dse said:
A good battery fully charged should read 12.8v, did you fully charge the new one before fitting as that is advisable as they may have been sitting on the shelf for some time.
Click to expand...
As Brian says, the battery voltage is way too low. The Hancook batteries on both mine seem to settle at 12.7 volts after the surface charge dissipates.
The MF31-1000 need charging for at least 24 hours with a 4 amp charger before fitting, you may have killed it already.
 
brianp38dse said:
Looking at the voltage the battery is dead 12.4v is dead 12,2v is even worse at those readings it will drop very low as you crank and cause all sort of mischief, mf31 1000 battery is what you need under £100 delivered from batterymegastore
Click to expand...

Is that real or a Nanocom thing? I'm sure it sometimes has slightly odd values but cannot remember which screens.
 
Jamieae said:
Update - I have now purchased a nano com to try and get to the bottom of this fault as even after speaking to several p38/Land Rover specialists/garages they all seem to say replace this/that which i have already done.

The readings were as follows.

(These were after driving the car so not completely cold temps etc)

Below are before starting/not running but when the glowplug light comes on and it had the starting issue

water temp - 134.52
Air temp - 84.19
Boost pressure - 251.27
Ambient pressure - 84.13
Throttle pot % - 0.00
Throttle pot V - 0.4
Battery - 12.04v
Low idle - 0.00
Cruise Status - Accel. Res

Below is as above not running but when it will start idle and drive as it should.

water temp - 97.80
Air temp - -38.88
Boost pressure - 105.74
Ambient pressure - 105.74
Throttle pot % - 0.00
Throttle pot V - 0.4
Battery - 12.22
Low idle - 750.75
Cruise Status - Cruise off

Both these readings are back to back so within seconds/minutes of each other.

as you can see when I have the issue as stated in the first post most of the sensors are reading high/wrong.

also the cruise control status is different.

Would this point to an ecu fault?

or any other ideas/suggestions?

I would like to get to the bottom of this but if not if anyone reading this is interested in a 2 owner 134k dhse with lots of history & good options (full wood interior & rear picnic tables etc) with many new parts such as air suspension&shocks, tyres, brakes, hoses etc please get in contact as I will probably pull it apart as many buyers won’t understand the “turn the key on & off three times if the glowplug light comes on issue”
Click to expand...

If you have MAF fitted then ignore the air temp as that will be a default value

That water temperature looks odd though.

Can you get it up to normal operating temperature (needle at 12 o'clock) and then record a trace onto an SD card?

I'll dig out my PC and try to find an old trace of mine (it'll be on this forum somewhere) although mine's pre-EGR and MAF so won't be exactly the same.
 
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