 | Home > Technical > Help! VCV/ ECU PROBLEM Scared I’ve bought a nail! |
 
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| whathaveidone Member Since: 18 May 2023 Location: Cheltenham Posts: 28   
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So. Fitted a reputable VCV joint tonight. Mechanically amazing. Starts, pulls, no flat spots. I had two momentary losses of power and all dials dropped and all lights on the dash then it came back but battery light stayed on. Despite this I drove another 20 minutes the car was fine. Thought I’d pull over and turn off ignition to reset battery light. Car wouldn’t start again. Battery fine, it clunks when turning the key but not turning over. Like starter motor problem. What do I have going on? It seems different every time I change the valve but that can’t be causing all this surely. Do I have a sick ÉCU? Car currently abandoned. ☹️😬
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22nd May 2023 7:07pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17452 
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These are not symptoms associated with a defective VCV and cannot be connected with the VCV. This suggests that there is a power interruption to the ignition circuit, and as a starting point I would check that the relays under the driver's seat are all making really good connections on their spade connectors. A very common cause of starting and/or running issues is one or more of the relay spade connectors being loose, usually either on the main ignition relay (causing starting and running issues) or the starter relay (starting issues). They easiest remedy is to remove the relay (which should be so tight in the socket that you almost need to lever it out with a screwdriver or similar) and very slightly bend the legs in a sort-of zig-zag so that they make a better contact with the female connector in the receptacle. It would be preferable to tighten up the female connectors but this is very much more difficult since it means freeing them from the receptacle first, space is limited, they are tight on the harness, and some of them are live. Tweaking the relay legs is usually satisfactory. It would also be worth checking the integrity of all the earth connections, including the engine/gearbox to chassis connection, chassis to battery connection, and the various earth connections on and around the bulkhead. The VCV is a fragile component and very prone to causing running issues. Generally however the VCV won't cause the engine to stop, but it will mimic very effectively the sort of misfiring symptoms that those of us who grew up on petrol-engined cars of the '60s and '70s associate with ignition or fuel problems, so random misfires, sudden severe power loss, and a general failure to respond correctly to suddenly-changing fuel or power demands such as when accelerating sharply. The purpose of the VCV is to regulate the common rail pressure by adjusting the supply of fuel from the LP stage of the fuel pump to the HP stage, so for example if you press the accelerator sharply to the floor the VCV should immediately respond to increase the common rail pressure. When they fail they seem initially to become sluggish, and then simply stop doing anything. The fuel system on the TDCi Defender is not very well monitored by the rather rudimentary ECM and as a result on of the symptoms to diagnose a VCV fault is poor running, misfiring, loss of power etc with a complete absence of stored DTCs in the ECM. If there are stored DTCs it is less likely that the VCV is the culprit. There is however absolutely no way that a faulty VCV could cause a sudden power loss and the complete loss of instrumentation on the dashboard, and the only thing I can immediately think of that could do this would be a loss of the ignition circuit, either power or ground, hence my suggestion above. You make no mention in your thread of owning or using a diagnostic tool, so I imagine that you probably don't have one. Sadly, it is extremely difficult to diagnose some of the TDCi engine faults without one, and it tends to become very expensive rather quickly if you have to rely on the trade for access to one. A relatively inexpensive tool such as the Nanocom will allow you to read and reset DTCs, really helpful for diagnosis, and also do things like monitoring the fuel rail pressure in real time, which is incredibly helpful when diagnosing those faults which don't result in DTCs (such as some of the rough running or failure-to-start faults). |
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23rd May 2023 12:44pm |
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| LandRoverAnorak Member Since: 17 Jul 2011 Location: Surrey Posts: 11324
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Notwithstanding all of the good and valid stuff above, that also sounds very similar to the symptoms of a failing ignition switch. Have a look here to see if it helps: https://www.defender2.net/forum/post933318.html#933318 Darren 110 USW BUILD THREAD - EXPEDITION TRAILER - 200tdi 90 BUILD THREAD - SANKEY TRAILER - IG@landroveranorak "You came in that thing? You're braver than I thought!" - Princess Leia |
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23rd May 2023 1:40pm |
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| MK Member Since: 28 Aug 2008 Location: Santiago Posts: 2427  
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Have you tried to override the starter relay? If the starter works then you can narrow the faults to the ignition or fuel supply. I cannot remember if the 2.4 has has an inertia switch. Probably it does not. Puma 110" SW
............................................................. Earth first. Other planets later |
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23rd May 2023 1:50pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17452
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A faulty ignition switch would certainly be a possibility.
You are correct, the 2.4 does not have an inertia switch per se, however I seem to recall that there is one incorporated into the 10AS unit although this will have no bearing on this fault. |
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23rd May 2023 2:13pm |
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| whathaveidone Member Since: 18 May 2023 Location: Cheltenham Posts: 28
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Thank you all so, so much for your kind help and advice. I was initially fairly confident I had vcv issues as changing the valves caused different fuel related symptoms or lack of. This lights on the dash thing is possibly just a coincidence. Just another idea, could I have shorted anything by cleaning the electrical contacts on the MAS and MAP I did this and also used EGR cleaner that seems to have coincided with the more electrical fault. Just to give more symptoms to this current stating issue. When ignition is in the first position I have lights, wipers etc. Going to the second position I get the loud clunk presumably solenoid but no start. Hopefully that helps with any diagnosis more. I’m going shortly to the car with a couple of pals and will look at the above suggestions as much as I can on the side of the road. I’ll also try and bump it? Thank you all again!
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23rd May 2023 2:52pm |
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| NickMc Member Since: 01 Oct 2014 Location: Norn Iron Posts: 1628  
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Other place I would look is for water ingress at the fuse box under dash
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23rd May 2023 6:51pm |
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| whathaveidone Member Since: 18 May 2023 Location: Cheltenham Posts: 28
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So the latest update… Went to get the car with a couple of kind volunteers. I had left the battery off over night hoping it would start. Same thing, turned key, solenoid thump and no starter. We bumped it and it started instantly. It drive home the best it has ever driven. Lots of power, no power loss. The original loss of power scenario seems to have been solved with the last (third) vcv valve. Nothing weird happened on the dash but the battery light remained on for the duration of the 25 minute journey. I got home, parked up, tried to start but the same solenoid clunk, no start. I’ll have a fiddle tonight with the items you kindly mentioned, wondered if any more suggestions given these current symptoms. Am i just unlucky with weird coincidences and has the starter simply failed. Could it be ÉCU related? Is it worth trying the hard reset I’ve read about? Thanks again in advance!
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24th May 2023 5:28am |
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| bear100 Member Since: 22 Mar 2010 Location: South Wales Posts: 1919  
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possible battery problem low cranking amps? can't stress enough about the relays under the seat especially the starter relay, its the usual suspect.
have you tried a starter pack? i always carry a NOCO70 (Halfords £100 with trade card) if it starts with a pack its more than likely the battery. check the alternator too, the battery light staying on tells me theres not enough charge going in. but your certainly on the right path  2016 Range Rover Autobiography 4.4 TDV8
2010 110 XS Utility 2.4TDCI 2010 Range Rover Sport TDV8 (gone) 2007 Discovery HSE TDV6 (gone) 1993 110 csw 200 tdi (gone) 1994 90 HT 300 tdi (gone) 1994 discovery 300tdi (gone) 90 hybrid 3.5 v8 (gone) Range rover bobtail 3.5 v8 (gone) |
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24th May 2023 6:23am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 17452
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I'd be inspecting the wiring in the vicinity of the starter carefully (which is not easy since it is absurdly inaccessible).
Normally a solenoid clonk and failure to start would make me think starter realy, ignition switch, harness, solenoid, or starter, but the charge warning light staying on is interesting. The alternator output is regulated by the ECM, but the output from the alternator (as I recall) is carried through a thick wire in the engine harness to the starter solenoid where it meets the permanent live feed to the solenoid coming from the battery. It is possible therefore that a connection problem at the solenoid could be causing both symptoms, so worth checking. The other common factor that could be causing both symptoms would be a defective earth connection between the (rubber-mounted) engine and gearbox and the chassis and battery. An earth fault could mess up charging and starting just as effectively as a faulty live connection as hypothesised above, and could in addition cause other strange effects such as you have noted earlier in the thread. Most of the components in the start circuit can be tested quite easily, so if inspecting your power and earth wiring reveals nothing, you can start bypassing possible faults (ignition switch, starter relay, etc) until you find a fault. |
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24th May 2023 1:44pm |
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| whathaveidone Member Since: 18 May 2023 Location: Cheltenham Posts: 28
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Thank you once again so much for taking the time. This all gives me something to go at. The car is not in the uk currently and it has rained the last few days preventing any progress. The sun is out today and for the weekend so I shall be crawling under and around the car tonight and tomorrow armed with some spanners, YouTube (to locate all said elements) and some patience. I will report back!
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26th May 2023 5:18am |
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| whathaveidone Member Since: 18 May 2023 Location: Cheltenham Posts: 28
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Quick update. Bumped the car this morning and it drove impeccably for my 15 mile journey. Great power, so I’m confident the original fault with the vcv is sorted. Solenoid still clunks when ignition goes to position 2, battery light remains on when driving. I tested the volts at the battery when running and it’s only 12.2v there so know why the battery light is on. A friend pulled some codes off the truck as below:
P167B Injector learning not done P0623 Generator lamp control circuit- signal stuck low P068A Ecm/ Pcm power relay De-energised too early. Damaged or faulty relay or connector So I’m presuming as per the amazing advice I have something loose, relay or fuse gone somewhere that has caused both the alternator and starter motor to fail simultaneously? I’ll double check this when I can get another bump by getting the volts direct from the alternator. Until then I’m going to take the seats out and start going through everything today. 🤞🏾🤞🏾🤞🏾 |
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27th May 2023 10:35am |
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| Ianh Member Since: 17 Sep 2018 Location: Essex Posts: 2044
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If you have a heavy duty jump lead directly connect the battery negative terminal to the engine. Thus creating a known good earth.
If engine starts ok and battery light is out you will know it’s an earth cable issue. Ps I’m assuming your battery clamps are tight and no other cables are connected via the battery clamp bolts ? |
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27th May 2023 1:01pm |
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| whathaveidone Member Since: 18 May 2023 Location: Cheltenham Posts: 28
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Great tip. Thank you. Just tried that without luck. All connections tried, relays well seated and swapped for new. Fuses all checked and good. I’m now at a bit of a loss… 😬
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27th May 2023 1:48pm |
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