 | Home > Puma (Tdci) > Puma loss of power and temp needle into red |
 
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| Naks Member Since: 27 Jan 2009 Location: Stellenbosch, ZA Posts: 2638   
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Yep, you should not be towing in 6th if the engine is working hard - you should gear down to 5th.
What you are describing sounds very much like the ECU putting the engine into limp mode to save it from damage. Sounds like you need a bigger intercooler -- 2010 Defender Puma 90 + BAS remap + Alive IC + Slickshift + Ashcroft ATB rear 2015 Range Rover Sport V8 Supercharged 
Defender Puma Workshop Manual: https://bit.ly/2zZ1en9 Discovery 4 Workshop Manual: https://bit.ly/2zXrtKO Range Rover/Sport L320/L322/L494 Workshop Manual: https://bit.ly/2zc58JQ |
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19th Sep 2013 5:19am |
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| arowson Member Since: 27 Jul 2013 Location: Penang Posts: 3  
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Thanks Naks. I have also contacted the main dealer in Perth, who sold the vehicle to me, as they serviced it only 1 week ago. They have promised to get back to me quickly. It will be interesting to see what they have to say. I cannot "drop in" to the workshop because I am now 2200km away.
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19th Sep 2013 9:15am |
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| Skye_Rover Member Since: 29 Aug 2013 Location: Skye Posts: 85  
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I believe, although I need to check my notes on this, from the descriptions given in the threads above, that the ECU is running into a boosted air temperature derate. This will occur in 6th gear if the engine is running near full-load at circa 1800rpm to 2500rpm, as this is where the compressor temperature limitation strategy is most aggressive. I don't fully understand why the engine would be dropping down to such low revs, but can only assume that the problem is caused whilst there is considerable load on the engine, therefore the load is sufficient to drag the speed down to idle. There will be a predictable time-lag between the car slowing and the air temperature coming back down again, not least that Puma 2.4 has to derive some parts of the air induction system temperature from a sensor that sits the other side of the intercooler. So a better intercooler will "fool" the controller model into not derating the compressor outlet temperature so quickly ( a simple curve is used to predict the intercooler temperature delta, not a measured value). To be absolutely confident that the compressor outlet temperature is not going through the roof, especially at altitude, a thermocouple probe should be fitted in the pipework that exits the turbo compressor, and a multimeter or similar device used to confirm that the air temperatures are staying down below 180celcius or thereabouts. Roads? Where we're going, we don't need roads. |
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19th Sep 2013 11:22pm |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
Not necessarily, if the coolant header tank cap is faulty it can cause coolant loss. As can a leak in the coolant pipe work,radiator etc. Check for contamination in the header tank and oil dipstick which can give you a heads up on a leaking head gasket, also visually check the head gasket looking for seepage, leaks etc. There is a tech bulletin for pre 2009 Pumas with reference to the fault you are having: Click image to enlarge Click image to enlarge Click image to enlarge Click image to enlarge
The Puma EMS has an overheating strategy to safe guard the engine. The overheating strategy comes in at 105 degrees C. The EMS uses the CHT sensor to monitor the head temp and once this reaches 105C the EMS initiates the overheating protocol. It does this by limiting the revs, reducing the rail pressure and where fitted, starts the aircon cooling fan in an attempt to lower the head temp. The IPAC temp gauge needle does not rise into the red zone until the engine reaches 105C. I recently tested this on my Puma towing a 3 tonne trailer up a small hill in 6th gear at 2500 rpm with an ambient air temp of 18C. I had my MSV plugged in and I monitored the live data page to get an accurate read on what the engine sensors reported. A few things are different on my Puma over standard so I was expecting the results to mirror this. The engine mods I have are, larger intercooler, stainless steel boost pipes, decat, straight through SS exhaust with one cherry bomb silencer, ITG air filter and a stage 2 remap from Alive with EGR closed . Prior to the test I ensured the tyre,s 265 MT were all inflated to the same pressure, the MAP/T and MAF sensor were removed and cleaned using carburettor cleaner. MAP/T sensor. Click image to enlarge Click image to enlarge MAF sensor. Click image to enlarge Click image to enlarge Click image to enlarge CHT sensor. Click image to enlarge The air filter was removed and cleaned, the associated electrical connections on the CHT, MAP/T, MAF and Turbo Modulator were cleaned in electrical contact cleaner. The coolant level was checked and didn't need topping up so I was confident that the cap was not leaking or that there was a leak elsewhere in the coolant system. Results were as expected, as engine load increases so does rail pressure and boost. As the revs drop black smoke starts appearing in the exhaust (unburn't fuel) As engine revs start to drop <2000rpm the CHT starts rising quite quickly and gets to 105C initiating the overheating strategy. Once the MSV showed CHT of 105C the IPAC gauge started to move up into the red and the engine lost power. I dipped the clutch and floored the accelerator and as expected the revs only climbed to about 1800rpm. I dropped down into fourth gear and released the clutch giving revs of 3500 rpm, I then floored the accelerator pedal with no increase in revs. Dropping down into 4th got the rheostatic fan roaring which increased the cooling capacity of the coolant system and as the CHT temp dropped down to 103C the revs came back in allowing me to accelerate again (down to 2000rpm in 4th now) which caused the CHT temp again to go above 105C and the revs to be limited again. I dropped down into second gear now and allowed the CHT to drop below 100C. I did the test again driving the Puma as intended when towing a heavy load. I used all the gears and revved up to 3500rpm before changing which resulted in an expected CHT maximum reading of 98C for the same test.
On the Puma there are two separate temp sensors on the induction side. The MAF sensor in the airbox and the MAP/T sensor on the inlet manifold. The EMS will then know the temp of the air entering the combustion chamber through the MAP/T sensor? Click image to enlarge Just my tuppence worth. :thumbsup: Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated  Last edited by Lorryman100 on 29th Sep 2013 5:03pm. Edited 1 time in total |
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20th Sep 2013 11:50am |
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| Skye_Rover Member Since: 29 Aug 2013 Location: Skye Posts: 85
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Correct in part. The MAP/T sensor is there to protect the (plastic) induction manifold from melting. What is also important is to manage the compressor outlet temperature, and for that to occur, the engine must derive how much cooling is occurring across the intercooler. This is not a fixed constant. Puma 2.4 has a number of protection strategies side-by-side, and they are not necessarily independant in the way they work, or how they derive data like turbine speed, pressure ratio, compressor temperature, etc. etc. Roads? Where we're going, we don't need roads.
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20th Sep 2013 12:43pm |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
The MAP/T sensor will show the temp of the air entering the intake manifold and the EMS will base the temps received on values/strategies stored within the fuelling file, so if the temp read at the MAP/T sensor was too high the EMS would drop boost and restrict rail pressure to safeguard the engine. To the driver it would seem as if the Puma has went into limp mode or the throttle was not responding. So if the Puma went into limp mode when towing a heavy load, high ambient air temp, altitude etc or a combination off them all resulting in a lack of power/boost etc and the CHT was below 105C then the cooling system is doing its job. Then we can talk theory and move onto the thermal transfer rate of the intercooler, the intercoolers heat absorption rate, Intercoolers flow rate in lb/min, intercoolers BTU/min, Turbo intake temperature, Turbo outlet temperature, pressure drop and a few other tedious calculations all to get to the point that at extreme conditions the oem intercooler isn't up to the job and a larger intercooler would solve a lot of the issues Puma drivers (IMHO) have when in hot climates towing heavy loads etc.
Mongolia, if it is definitely not a cooling issue (CHT, Coolant loss etc) have a read of the Adiabatic Processes and use the Turbo Outlet Temperature Calculator and the Intercooler Outlet Temperature and Pressure Calculator to determine if your oem set up is up to the conditions and what would be required in a new intercooler to meet your requirements. http://www.stealth316.com/2-adiabat1.htm http://www.stealth316.com/2-turbotemp.htm Just my tuppence worth.  |
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22nd Sep 2013 3:32pm |
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| arowson Member Since: 27 Jul 2013 Location: Penang Posts: 3
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I guess the conclusions are:-
a) get a better intercooler b) when towing heavy loads, in hot conditions, keep the revs up (say around 3,000 - 3,500) to maximize cooling. Thanks to Skye Rover and Lorryman for all of their input. |
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23rd Sep 2013 11:09pm |
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| tuesdayfox Member Since: 23 Jun 2013 Location: Sydney,OZ Posts: 129 
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I had the same problem...
turns out the turbo hose...  |
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25th Sep 2013 2:02am |
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| Skye_Rover Member Since: 29 Aug 2013 Location: Skye Posts: 85
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Which is pretty common on the 300Tdi intercooler hoses. Sustained towing or driving at high loads or at altitude can raise the compressor outlet temperatures enough to start delaminating the flexible hoses between the engine and the intercooler. Especially the flexi hose at the compressor itself. The easy fix is to replace all of the hoses with new silicon aftermarket items.
When the hose delaminates, the inner skin will balloon out under higher airflows, then block the intake system (even though the turbo is compressing the air in front of the balloon). This skin of rubber will then collapse back outwards when the engine is slowed or stopped. And so the whole process repeats over again. It is visible if you have the MAP signal logged when the derate occurs, because the signal will fall significantly below barometric pressure, which the engine cannot do by derating. Any OBD scan tool can log this sort of thing, it doesn't need to be expensive. Roads? Where we're going, we don't need roads. |
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26th Sep 2013 11:25pm |
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| rcwilliams Member Since: 21 Jul 2014 Location: Dijon Posts: 1 
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Hi,
It's looking like I need to replace the CHT sensor, but how on earth to I get in there to do it? Just not enough space for a spanner! Any tips please? many thanks |
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11th Aug 2022 2:38pm |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2416  
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Td4, 2007. Oil cooler thermostat+lower Temp main thermostat? Puma 110" SW
............................................................. Earth first. Other planets later |
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11th Aug 2022 10:43pm |
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