 | Home > Puma (Tdci) > Intermittent limp home mode.. |
 
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| Tim_NZ Member Since: 05 May 2008 Location: Australia Posts: 177  
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Could be a number of things, but I'd start with the Cylinder Head Temperature sensor.
Cheers, Tim |
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2nd Nov 2011 11:00pm |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
Need a little bit more info for us to be able to offer you any help. Though here are a few of my initial thoughts
The MIL does not illuminate? Does it illuminate when you switch the ignition on (self test)? Bulb blown? Have you had a similar issue in the past which rectified itself? Is the Key fob battery OK? Passive immobilizer. Have you been in deep mud lately? Blocked tank breather Do you see fuel dripping from underneath when you overfill the tank? Not had the extension pipe fitted as per SB. Does the temp gauge rise into the red? CHT sensor, low coolant, restricted coolant pipe, engine enters limp mode to protect engine from overheating. MIL and DTC logged When was it last serviced? Fuel filter needs replacing. Has it had any fuel rail issues? P1169? Faulty rail pressure sensor, Pressure Limiting valve activated. MIL and DTC logged The fact that the MIL did not illuminate means it is most likely a fuelling issue rather than electrical which helps narrow things down somewhat, as the MIL should illuminate if the EMS has instigated the limp mode. If you post more info on the circumstances surrounding the issue then I'm sure some one on here will be able to help.
Brian. |
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3rd Nov 2011 12:33am |
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| BigMike Member Since: 13 Jul 2010 Location: Lancashire Posts: 2253 
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to add to Bris list:
high pressure fuel pump blocked fuel pick up - you stop and wait, the blockage drifts out of the pick up back into the tank. it d be most noticeable if the fault appears when the vehicle is under heavy load ie high gear, long hill, foot to the floor. neither of these will give MIL lights. |
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3rd Nov 2011 12:52am |
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| LR90XS2011 Member Since: 05 Apr 2011 Location: bickenhill Posts: 3641 
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Id Just like to say the willingness of people on here to try and help fellow owners always impresses me
thanks chaps. DEFENDER 90 TDCI XS, I hope everyone is well and your land rovers make you happy |
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3rd Nov 2011 5:40am |
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| MD5 Member Since: 02 May 2011 Location: Italy Posts: 143 
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Thanks to Lorryman for the troubleshooting information!
@BigMike: Could you please better describe the -high pressure fuel pump blocked fuel pick up- problem ? Last Sunday, when driving across a steep and rocky hill suddently my puma lost most of the power without MIL light or other kind of warning. I then switched off the engine to check if something was wrong in engine vane and then, after turning on the engine everything run fine, no more problems detected. It wasn't a overheat problem because the engine was just turned on after a lunch. |
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3rd Nov 2011 6:38am |
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| BigMike Member Since: 13 Jul 2010 Location: Lancashire Posts: 2253
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Ok you're driving along at 70 on flat road, you get to a long hill. Naturally you start to lose speed so you put your foot down. It responds buy further up the hill there is a short power interruption. You lift on and apply power again and it goes but doesn't really seem like it wants to foot down hard again and it slows. You stop for 5 minutes and when you carry on it's fine for a while
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3rd Nov 2011 8:58am |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
The problem with fault finding and rectification on a forum is the lack of pertinent information in relation to the fault received. There are a few problems that can cause these issues starting at a few hours of your time up to thousands of pounds in parts and labour costs. Personally I start with the, my time option first. So what can cause the lack of power with no MIL or dtc's stored? Basically the vehicle occasionally doesn't respond to the power being asked of it, so what can cause this that I can check without any diagnostic gear? So lets look at fuel starvation first, is there fuel in the tank? have you filled from a jerry can? are there any diesel leaks? is the breather on the fuel cap blocked? is the tank breather blocked? is the fuel filter dirty or has water in it? Any leaks on the fuel pump? any leaks at the accumulator rail? has the pressure limiting valve operated?
If these all look OK and have been checked lets move onto the tank pick up pipe, this involves removing the fuel tank and removing the complete sender/fuel pick up/return unit and clearing the pick up pipe with an air line to clear any detritus. If none is found then I would move onto the Fuel pump, but first let me explain how it works. The fuel pump contains and controls both the low pressure and high pressure systems. The low pressure side of the pump is responsible for getting the fuel from/and return to the tank and into the pump to be utilized in the high pressure system. It does this by using an eccentric cam to draw fuel along the fuel pipes and into the pump. There is an admissions valve to control the volume (also ensures that sufficient lubrication and cooling are always provided for the high-pressure pump components) and also a temp sensor to determine the fuel density by its temperature, if this sensor is faulty or unplugged the defender will enter limp mode. Fuel is then passed into the high pressure side by way of the Volume Control Valve which is controlled by the EMS. It basically governs the flow of fuel from the low to the high pressure side to maintain the fuel accumulator rail at a set pressure. It operates by means of the EMS using the information from the fuel rail pressure sensor to maintain the pressure at the fuel rail, about 1600BAR. A total of 2 high-pressure chambers, each with a pump plunger, are used for high-pressure generation. The drive for the pump plungers is through an eccentric cam, which is in turn driven by the drive shaft. The high-pressure pump permanently generates the high system pressure for the fuel rail. The rotary movement of the drive shaft is converted to a reciprocating movement by the eccentric cam. The eccentric cam ring then transfers the reciprocating movement to the pump plungers. The pump plungers are offset by 180 degrees. This means that during a reciprocating movement, pump plunger 1 performs exactly the opposite movement to pump plunger 2. When the eccentric cam produces an upward stroke, pump plunger 1 moves in the direction of Top Dead Center (TDC), thus compressing the fuel and delivering it to the fuel rail via the outlet valve. The inlet valve is pressed into its seat by the delivery pressure. Pump plunger 2 is moved by the tension spring force in the direction of Bottom Dead Center (BDC). Due to the high pressure in the fuel rail, the outlet valve is pressed into its seat. The pump internal pressure opens the inlet valve and fuel flows into the high-pressure chamber. When the eccentric cam produces a downward stroke, the process is reversed. So if we check the pressure at the rail, we can see if the high pressure pump is causing the issue. If not then the low pressure system must also be not at fault as it supplies the high pressure system. So next on the list is the injectors themselves, not much here you can check without removing them, and if you do you will need new copper washers first to replace the old ones. The faults here range from broken actuator springs to cracked pressure casings. Though if an injector was failing/failed then the solenoid on top would not operate as intended and would throw up a dtc in the EMS? So lets now check the electrical side of the fuel system, on the pump itself there are only two electrical connections and the VCV is the only replacement part. The temp sensor tells the EMS the fuel temp and this in turn allows the EMS to gauge fuel density. If the sensor was unplugged/faulty the engine would enter limp/reduced power mode. The Volume Control Valve works by being energized by a 12v circuit to fully open the valve. The EMS controls the valve opening by use of ground, so when you switch on the ignition the VCV opens fully and is then controlled by the EMS once running. When the ignition is switched off the valve closes completely as it has no power. This part is replaceable and is responsible for controlling the fuel entering the high pressure system to maintain the rail pressure. It works in conjunction with the fuel rail pressure sensor and both are controlled/report to the EMS. If the fuel rail pressure sensor is unplugged/faulty the engine will enter limp/reduced power mode. The injector solenoid is what controls how much fuel goes into the combustion chamber and opening times are controlled by the EMS utilizing the Crankshaft position sensor (CKP) and the Camshaft position sensor (CMP) to control firing cycle. The problem here is that with the Pumas electrical sensor issues a MIL and DTC should be logged whenever a problem crops up. So we have checked and discounted the fuel system as the cause, so now we move onto the induction side of the engine. Check the air filter, induction feed to the intercooler and onto the inlet manifold for obstructions, crushed plastic pipes etc. Next we have the EGR valve, easiest way to check if this is the issue is when you shut down you should hear the 5x chukka chukkas of the self clean cycle. If you do you know the valve is closed, so unplug it and go for a run and see if the issues are resolved. You will get the MIL and DTC's logged when you unplug it and it may enter limp mode so just reset the ignition and it will clear. If the issue still remains then you know the EGR is not at fault. Next we come to the Turbocharger unit. Sticking actuator arms will cause issues with over/underboost issues which in overboosts case will put the engine into limp mode to protect the turbo unit from damage. The Modulator/harness could be at fault, but the sensor the EMS uses would be the first thing I would put a DMM on, the MAP sensor. I am going to stop here as I'll have you taking the engine out next and rebuilding it or putting a TDV8 in instead.  
My advice would be to get a diagnostic tool on it first to see what DTC's both tested and untested are logged to see if that will pinpoint the issue. It is very hard to diagnose a problem from a forum and it could be something simple and trivial that is causing the issue. After that it is just a case of starting to fault find and try to diagnose the problem or you can always put it into the dealers. Brian. |
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3rd Nov 2011 12:19pm |
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| MD5 Member Since: 02 May 2011 Location: Italy Posts: 143
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Thanks to BigMile for answering my question.
I'm amazed about the Lorryman100 fault finding writing, a huge thanks! I just received a cheap OBD-2 to USB interface to read the DTC codes. Tomorrow I will connect and read any possible DTC stored i my 110. I will post the result. |
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3rd Nov 2011 8:14pm |
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| MD5 Member Since: 02 May 2011 Location: Italy Posts: 143
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The problem related to -high pressure fuel pump blocked fuel pick up- may be accompanied by a subtle intermittent noise like a sob or chirping, apparently coming from the engine compartment ?
Which is the cause and possible cure to avoid this fault ? Note: Sorry for my bad english!  |
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4th Nov 2011 5:28am |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
Sorry I don't really understand your post. Are you saying that you have a faulty fuel pump/tank pick up, and you are hearing chirping/sob sounds because of that? Or you are hearing these noises and believe it to be the fuel pump/tank pick up?
Brian. |
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5th Nov 2011 3:32pm |
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| MD5 Member Since: 02 May 2011 Location: Italy Posts: 143
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I apologize for my bad english!
I mean if this kind of noise can be related to the high pressure fuel pump blocked fuel pick up. |
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5th Nov 2011 3:43pm |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
Without hearing the noises I would first check the induction side first. Check the Turbo hoses and the intercooler for air leaks. Also that the MAF sensor is in its seat and is not leaking, air filter lid is on properly and all plastic ducting is hiss free. Check the MAP sensor is sealed and the induction pipe work into the inlet manifold is not leaking.
Brian. |
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5th Nov 2011 4:05pm |
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| MD5 Member Since: 02 May 2011 Location: Italy Posts: 143
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Thanks for the advice, I will do the check. In the meantime I read the DTC fault memory but it's empty.
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5th Nov 2011 7:41pm |
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| Lorryman100 Member Since: 01 Oct 2010 Location: Here Posts: 2686 |
The fault DTC may not show up on a generic OBD11 reader as it cannot read manufacturers specific codes. Have a read of this post I did on another thread as it will explain what I mean:
Brian. |
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5th Nov 2011 7:49pm |
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