Help I've bought a p38 Dhse with issues, I'll never learn!

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KeepBuyingCheapOldCrap

KeepBuyingCheapOldCrap

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Location
North Wales
Hi
Been lurking around the forum for a while, recently purchased a v reg p38 Dhse automatic and of course it has issues.
Problem is a serious lack of power when cold, won't even pull away flat out! Let it warm up and it drives well as pokey as these diesels get.
Full story, its a late model dse but someone has fitted a early metal inlet m reg engine (engine was manual) and ecu (immobiliser off) with a modified 'butchered' wiring loom to suit the auto.
Engine has a one pin brown coolant sensor (dash cluster?) and a 2 pin green sensor (ecu?) I suspected coolant temp sensor faulty, plugged a new one in no difference, diag live data looks terrible like its not reading correctly (see pics).
Is this the correct ecu (see pics) to run this engine? Should I get a new early auto engine loom? Should I try and put the car back to later ecu maf egr etc.
I ran a Bmw e34 525 tds for many years and love the M51 engine but the rangey is a bit different!
Any help from the p38 diesel gurus appreciated.
Thanks Rhys
 

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KeepBuyingCheapOldCrap said:
Hi
Been lurking around the forum for a while, recently purchased a v reg p38 Dhse automatic and of course it has issues.
Problem is a serious lack of power when cold, won't even pull away flat out! Let it warm up and it drives well as pokey as these diesels get.
Click to expand...
As in the revs go up but the car doesn't move?
If that's the case have a look at the ZF4HP22 FAQs on Ashcroft Transmission's site esp those relating to issues caused by low fluid and blocked filter screens.
Ashcroft Transmissions (ashcroft-transmissions.co.uk)
 
Hi
Doesn't even try and rev up in gear. Knock into neutral and rev it up a few times back into drive and it'll move but not full power until up to temp. Used low range earlier to pull off into the workshop easier haha won't climb onto a 4 poster when cold!
Cheers for the info there, looks like the car has had a recent transmission cooler and custom pipes made up (quite nice actually) hoping the fluid level is correct, haven't checked yet
 
Likelihood is it’s many little things, autobox sounds main culprit. Sounds like it’s been butchered in and many fixes with these vehicles is putting back PO bodges to standard.

Green sensor is edc temp sender for ecu, brown is earthed through the body means it’s non aircon that’s the gauge sender.
I prefer the metal inlet engines myself, less nonsense like MAF in the mix. No point putting EGR on just to block it off or guff up your engine

Check your MAP pipe as reading shows zero ^^^. It will struggle to pull away if that’s duff/missing/feed pipe split as turbo won’t kick in.
 
Will have a look at the gearbox oil level, fill plug in the side of the box as it's a later one?
Will unplug the map sensor and see if it goes even slower on the way to work.
Just concerns me why so many sensors are reading incorrectly on diag but it could just be the snap on reader.
What are the differences in ecu plug /loom on late vs early models.
Last thing under the inlet where the black electric box is, towards the bell housing there's a female plug that looks green inside, where is that meant to go? I'll get a pic shortly.
Cheers
 
You will very lucky if you can get a snapon diag to talk to a p38 doozel properly, they are not obd compliant, there are only two or three dedicated units that will do it, genuine JLR testbook at eye watering price, Blackbox solutions kit ie nanocom, and one other,
if you have an early engine and a later egr engine loom there will a plug that should go on to a third sensor in the head that is not on the early engines and the maf sensor on the inlet ducting, unless they put the complete engine, loom and ecu in
 
brianp38dse said:
You will very lucky if you can get a snapon diag to talk to a p38 doozel properly, they are not obd compliant, there are only two or three dedicated units that will do it, genuine JLR testbook at eye watering price, Blackbox solutions kit ie nanocom, and one other,
if you have an early engine and a later egr engine loom there will a plug that should go on to a third sensor in the head that is not on the early engines and the maf sensor on the inlet ducting, unless they put the complete engine, loom and ecu in
Click to expand...

Can you remember if the later engine actually takes the inlet air temperature? The MAF engines just use a default value but I don't know if the wiring is still there.

Also, I've a feeling the engine ECU for the automatic might be different, especially on early models so that might cause issues. Then there's the manual or auto setting in the BECM.

The engine might even be out of an Omega.
 
Looking at those readings, you have a coolant reading of -35 degrees for some reason. I doubt the electronics will allow the engine to rev until it warms up as it thinks it is in the artic, under ice, so trying to prevent engine damage. Maybe a bad sensor, maybe a bad connection, open circuit in any case. Pull the plug, short it and see if that makes a difference when cold.
 
KeepBuyingCheapOldCrap said:
Will have a look at the gearbox oil level, fill plug in the side of the box as it's a later one?
Will unplug the map sensor and see if it goes even slower on the way to work.
Just concerns me why so many sensors are reading incorrectly on diag but it could just be the snap on reader.
What are the differences in ecu plug /loom on late vs early models.
Last thing under the inlet where the black electric box is, towards the bell housing there's a female plug that looks green inside, where is that meant to go? I'll get a pic shortly.
Cheers
Click to expand...
That plug is probably for the third (black) sensor which brings in the A/C fans in the event of an overheat on the later engine.there should be a blanking plug in the head which can be removed to fit the sensor.
 
Marshall8hp said:
Looking at those readings, you have a coolant reading of -35 degrees for some reason. I doubt the electronics will allow the engine to rev until it warms up as it thinks it is in the artic, under ice, so trying to prevent engine damage. Maybe a bad sensor, maybe a bad connection, open circuit in any case. Pull the plug, short it and see if that makes a difference when cold.
Click to expand...

Might be the IAT. On the MAF version that has a preset of minus something silly because it uses the MAF value instead. Early ECU won't handle MAF and will not have IAT preset.
 
KeepBuyingCheapOldCrap said:
Hi
Been lurking around the forum for a while, recently purchased a v reg p38 Dhse automatic and of course it has issues.
Problem is a serious lack of power when cold, won't even pull away flat out! Let it warm up and it drives well as pokey as these diesels get.
Full story, its a late model dse but someone has fitted a early metal inlet m reg engine (engine was manual) and ecu (immobiliser off) with a modified 'butchered' wiring loom to suit the auto.
Engine has a one pin brown coolant sensor (dash cluster?) and a 2 pin green sensor (ecu?) I suspected coolant temp sensor faulty, plugged a new one in no difference, diag live data looks terrible like its not reading correctly (see pics).
Is this the correct ecu (see pics) to run this engine? Should I get a new early auto engine loom? Should I try and put the car back to later ecu maf egr etc.
I ran a Bmw e34 525 tds for many years and love the M51 engine but the rangey is a bit different!
Any help from the p38 diesel gurus appreciated.
Thanks Rhys
Click to expand...
I have done this to my P38 , fitted earlier engine. Does yours still have the MAF all plugged in just from the airfilter box. If so unplug the MAF and see if there is a difference. The late wammers explained to me that because of the engine and change and sensors being different the MAF now does a slightly different job on the performance of the car. If it runs ok leave disconnected until you get a new MAF. They are silly money but be wary of cheap Chinese copies as they don't last long(experience taught me this) . I was fortunate to buy a second hand original from some one breaking a P38
 
brianp38dse said:
You will very lucky if you can get a snapon diag to talk to a p38 doozel properly, they are not obd compliant, there are only two or three dedicated units that will do it, genuine JLR testbook at eye watering price, Blackbox solutions kit ie nanocom, and one other,
if you have an early engine and a later egr engine loom there will a plug that should go on to a third sensor in the head that is not on the early engines and the maf sensor on the inlet ducting, unless they put the complete engine, loom and ecu in
Click to expand...

I do have access to jlr test book will try and give that a go maf sensor is there but just being a bit of pipe to connect airbox.
My educated guess is that the loom is a early manual one modified to automatic. As the inlet air temp sensor wiring is all there. Definitely a mix of parts!
 
Rubberknees said:
I have done this to my P38 , fitted earlier engine. Does yours still have the MAF all plugged in just from the airfilter box. If so unplug the MAF and see if there is a difference. The late wammers explained to me that because of the engine and change and sensors being different the MAF now does a slightly different job on the performance of the car. If it runs ok leave disconnected until you get a new MAF. They are silly money but be wary of cheap Chinese copies as they don't last long(experience taught me this) . I was fortunate to buy a second hand original from some one breaking a P38
Click to expand...

So you fitted a early engine but kept the later ecu and maf sensor etc? Does the early high pressure pump work with the later ecu? Mines running a early ecu so I presume the maf is redundant.
 
Grrrrrr said:
Might be the IAT. On the MAF version that has a preset of minus something silly because it uses the MAF value instead. Early ECU won't handle MAF and will not have IAT preset.
Click to expand...

Great info cheers, but with this butchered mash up running a early ecu is the maf now a paper weight? There is a intake temp sensor fitted in
Grrrrrr said:
All pumps are the same and should end 994.
Click to expand...

Ah awesome, I'm coming from bmw and there was different pump numbers and they had to correspond to the correct pump. Crude immobiliser really.
So why the fek has the previous owner cocked about with the wiring loom and ecu if he could of just ran the original ecu and loom with maf on the early engine?!
Shall I just put everything back to later spec ecu, etc?
 
KeepBuyingCheapOldCrap said:
Great info cheers, but with this butchered mash up running a early ecu is the maf now a paper weight? There is a intake temp sensor fitted in


Ah awesome, I'm coming from bmw and there was different pump numbers and they had to correspond to the correct pump. Crude immobiliser really.
So why the fek has the previous owner cocked about with the wiring loom and ecu if he could of just ran the original ecu and loom with maf on the early engine?!
Shall I just put everything back to later spec ecu, etc?
Click to expand...
Thats how mine runs and its fine(eek) Don't see why previous owner did all the butchering and swapping
 
Rubberknees said:
Thats how mine runs and its fine(eek) Don't see why previous owner did all the butchering and swapping
Click to expand...

I suspect if he hacked a manual ECU to work with an automatic one there will have been some fettling. I just don't know enough about it. Not for the first time we are missing Wammers and his knowledge. I guess he might have answered this in the past. Datatek might know, although I am not sure how much he has played with the manual.
 
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