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  #11  
Old 27th-November-2010, 10:27
wammers's Avatar
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Join Date: Oct 2008
Location: Preston Lancs.
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Default Re: p38 diesel issues

Quote:
Originally Posted by hendoaaron View Post
hi there this is for wammers!

thanks for your comment! not needed fella!

i am very aware how a stat works!

there two sensors for the coolant temp on a p38 diesel the front one feeds gauge for temp reading obviously also feeds ecu for fuel consumption to pump etc, and the rear one gives ecu a signal to turn on glow plugs depending on coolant temp.
for some reason not known to me but we do own p38 there are sent to try us! the p38 software when the coolant is hot can tell the ecu not turn on glow plugs hence no start or takes a while. i recieved this info from a colleague who knows these things well, my fuel consumption hasnt changed since ive done it and i get engine coolant temp fine on my gauge.
the reason my p38 was running cold was vicous fan permantly on so it sorted now.

but yes thanks for your smart comments!

to the other lads on here many thanks for all your help
One sensor feeds the gauge on the dash only, the other one, the one you have stupidly disconnected and jury rigged feeds the ECU to inform it of engine temp changes and so fueling adjustment and glow plug operation. Best thing if you don't understand something, which you obviously don't. Bettter not to mess with it. Rather like putting your central heating thermostat outside don't you think. If you do stupid things expect to have your leg pulled. Have a nice day.

Last edited by wammers; 27th-November-2010 at 10:38.
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  #12  
Old 27th-November-2010, 22:11
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Posts: 41
Default Re: p38 diesel issues

yeah it was

the vicous fan was on permantly so it was thats why running cold runs like a dream now. i have been told by a range rover mechanic that that sensor doesnt effect the fuel consumption. plus it didnt make any difference to my fuel economy afdter i did it
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  #13  
Old 27th-November-2010, 22:23
the hooded claw's Avatar
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Location: Fleetwood Lancs, Besides the Sea!!!
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Default Re: p38 diesel issues

Quote:
Originally Posted by hendoaaron View Post
yeah it was

the vicous fan was on permantly so it was thats why running cold runs like a dream now. i have been told by a range rover mechanic that that sensor doesnt effect the fuel consumption. plus it didnt make any difference to my fuel economy afdter i did it
Firstly "Viscous Fans" ALWAYS run "Perminantly" (As they are turned by the god damned engine) Do you by any chance mean the front electric cooling fans ???? ....

Explain please ....................

Quote:
there two sensors for the coolant temp on a p38 diesel the front one feeds gauge for temp reading obviously also feeds ecu for fuel consumption to pump etc,
DEAD WRONG there Matey!!!!

Last edited by the hooded claw; 27th-November-2010 at 22:26.
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  #14  
Old 28th-November-2010, 02:19
wammers's Avatar
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Default Re: p38 diesel issues

Quote:
Originally Posted by hendoaaron View Post
yeah it was

the vicous fan was on permantly so it was thats why running cold runs like a dream now. i have been told by a range rover mechanic that that sensor doesnt effect the fuel consumption. plus it didnt make any difference to my fuel economy afdter i did it
Your mechanic is wrong, god help his customers. The ECU engine temp sensor, along with inlet air temp sensor and fuel temp sensor pass information to the ECU. The ECU then computes that information and instructs the fuel pump to deliver differing amounts of fuel for a given engine, inlet air, fuel temp. The throttle position sensor, and engine speed sensor along with the number four injector control injection and injection timing over the rev range, via the ECU. The MAP sensor adjusts fueling via the ECU for differing manifold pressures. If the ECU temp sender is constantly cold the engine will run at cold start settings all the time. If the ECU temp sensor fails and the ECU thinks the engine is hot all the time you will have trouble cold starting. But from your other posts it would seem you have a problem with the glow plugs. The glow plugs should not work when engine is hot unless you have the hot start fix fitted. When the engine is cold you should be able hold the viscous fan with finger pressure whilst the engine is started. But not be able to when the engine is hot. A rolled newspaper maybe better than your fingers if you don't know what your doing.

Last edited by wammers; 28th-November-2010 at 02:21.
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  #15  
Old 28th-November-2010, 09:17
Datatek's Avatar
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Default Re: p38 diesel issues

Quote:
Originally Posted by hendoaaron View Post
yeah it was

the vicous fan was on permantly so it was thats why running cold runs like a dream now. i have been told by a range rover mechanic that that sensor doesnt effect the fuel consumption. plus it didnt make any difference to my fuel economy afdter i did it
So, just how many (or how few) miles to the gallon do you get? You have to remember the LR skimped every penny they could on production, no way would they fit a sensor that was not needed.
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  #16  
Old 28th-November-2010, 10:54
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Default Re: p38 diesel issues

I`ve nothing to add to the comments about the temp sensors. Wammers & Datatek have covered that well, and Hoodie is being his normal laid-back self with his comments on the fans, (they are vicious if you try `n` stop one with your fingers tho`).
I would like to add a comment about the OP query about turbos tho`. As Mike says SOME oil is blown from the turbo into the intercooler, but excessive oil in the inlet can be a warning of problems.
If the engine is using oil with no visible drips then investigate further.
With warm engine let it tickover for 10 mins, then boot it, blue smoke? Investigate.
With cold engine take pipe off turbo insert finger.(Warm hands so as not to make her squeal) If you can fell any play on the turbo shaft/vanes or any roughness is evedent on edges (small mirror helpful here); investigate further.
If you`ve all the above symptoms you have a shot turbo.
Turbos can fail in different ways, but if you`re unlucky they can take out the whole engine with them. (bits of turbo sucked thro intercooler into pots, and/or a runaway situation as the engine runs out of control on lube oil). That`s a worst case scenario but be warned.
That`s me off my hobby-horse again.

PS Always use good quality oil ETC ETC and you don`t say what milage the engine is on?

Last edited by gtland; 28th-November-2010 at 10:58. Reason: Add PS
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  #17  
Old 28th-November-2010, 11:16
wammers's Avatar
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Default Re: p38 diesel issues

Quote:
Originally Posted by gtland View Post
I`ve nothing to add to the comments about the temp sensors. Wammers & Datatek have covered that well, and Hoodie is being his normal laid-back self with his comments on the fans, (they are vicious if you try `n` stop one with your fingers tho`).
I would like to add a comment about the OP query about turbos tho`. As Mike says SOME oil is blown from the turbo into the intercooler, but excessive oil in the inlet can be a warning of problems.
If the engine is using oil with no visible drips then investigate further.
With warm engine let it tickover for 10 mins, then boot it, blue smoke? Investigate.
With cold engine take pipe off turbo insert finger.(Warm hands so as not to make her squeal) If you can fell any play on the turbo shaft/vanes or any roughness is evedent on edges (small mirror helpful here); investigate further.
If you`ve all the above symptoms you have a shot turbo.
Turbos can fail in different ways, but if you`re unlucky they can take out the whole engine with them. (bits of turbo sucked thro intercooler into pots, and/or a runaway situation as the engine runs out of control on lube oil). That`s a worst case scenario but be warned.
That`s me off my hobby-horse again.

PS Always use good quality oil ETC ETC and you don`t say what milage the engine is on?
Yeah just to add to the fan stopping thing. I did say they can be held when cold by finger pressure whilst the engine is started. I would not recommend sticking your fingers in there with the engine running, in particular if you've never done it before, were getting the rotation wrong can be a little painful. That's why i mentioned the rolled newspaper. Less blood that way.
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  #18  
Old 28th-November-2010, 11:19
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Default Re: p38 diesel issues

Practical experience is often the best teacher, but think we agree this is an exception!
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