 | Home > Puma (Tdci) > Eratic Idle especially when cold |
 
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7687  
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http://www.defender2.net/forum/topic26346.html
this post Cheers James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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21st Sep 2017 3:28pm |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16879  
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I believe that it is actually a ball bearing crimped onto a seat. When the pressure rises to a set point, the crimp fails and the bearing comes out. EGR problems are common on the TDCi motor, but (unlike VCV problems) usually produce DTCs (one of the pointers to a problem being the VCV is an absence of DTCs.) A EGR valve stuck open will impact the running, and will have most impact at low engine speeds. An erratic tickover is a known symptom of an EGR vavle failing to close. It is also a fallacy that the EGR valve should make the "chukka chukka" sound when self-cleaning on engine stop. A perfectly-working EGR is almost silent in operation and you'd have to losten very carefully to hear it. Perfectly-working EGRs are very rare (I've only met about 2 that are quiet in the last 10 years), and the noise is common. So the "chukka chukka" is normal rather than correct, but it does indicate that the valve is operating although it doesn't necessarily mean that it is operating correctly, nor closing fully. As a general diagnostic rule on the TDCi, if the engine is running badly, misfiring, losing power, and has a rough tickover look for DTCs. If none, suspect the VCV. If there are DTCs relating in anyway to EGR, suspect the EGR, or if there are DTCs relating in anyway to manifold pressures, overboost, underboost, etc, suspect the intercooler pipes, turbo actuator, MAF or MAP sensors, or possibly EGR, although these are less likely to cause rough tickover. |
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21st Sep 2017 5:50pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233  
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As I said I'm not convinced the egr can cause the erratic idle and stalling problem in the first place so even if it is not fully closing with its extremely strong spring action then it's going to be a constant small gas leak so why would that cause erratic engine revs when it's held in a constant position? Whereas, when it's electrically connected it's valve position will be changing under control of tge ECU although to be fair it only really opens during deceleration or when the load is taken off the engine. By removing the control to the EGR you are effectively taking away another variable so if there is no change to the problem it's unlikely to be the cause. Taking the egr out to see that it is closing would be one certain way to eliminate your identified possibility but it's a pig to get in or out so I would try my simple suggestion and see what result you get. "You are never to old to learn something new"
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21st Sep 2017 5:53pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7687
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understood, thank you Cheers
James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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21st Sep 2017 6:11pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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The EGR valve has a crude gearbox, a 12 v electric motor drives a small sprocket on the end of the motor shaft the then turns a larger gear on the valve shaft. A cam type action converts rotary motion to a linear pull of the valve against a strong spring. It's hard for the crude gearbox not to make an audible noise when the cleaning cycle rapidly opens and closes the valve fully 4 times at engine off. It's easy to test the EGR is doing this action but unplugging the connector to it and then connecting 12V across the motor pins in the EGR connector. They are the two pins that are on there own. If you get the polarity wrong the motor will just try and drive it hard into the closed stop position and you will not hear it operate but if you reverse the connection it turns the motor in the correct direction and it will fully open the valve. On removing the 12V you should hear it wind itself back shut under the spring action. In one of my posts there is a photo of the connector pins you connect to. Note you need about 4 amps at 12V if you are using an external power supply. A standard car battery charger should be sufficient. "You are never to old to learn something new" |
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21st Sep 2017 6:30pm |
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| OleDave Member Since: 19 Oct 2013 Location: CARDIFF Posts: 175 
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Hi Guys, well some very useful information from all so thank you very much for all the replies, I am asuming that if a fault code is showing re the egr valve that the fault relates to either the valve not opening or not closing correctly or that the gas flows are incorrect due to either of the aforementioned? has anyone ever had these valves to pieces for a good scrub? have done that a few times on other makes of vehicle with some success, have seen a few totally choked with carbon along with the pipework, at that time stripdown was done due to lack of performance and or pumping out black smoke but as far as I can remember none were dismantled or replaced due to eratic idle or cuttting the engine out!
Regards Ole Dave |
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21st Sep 2017 7:46pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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Yes OleDave, I've had a few apart.
They are not that complicated. See post "EGR Fault" at http://www.defender2.net/forum/topic47507.html in my case all the ones I've looked have just had light sooting around valve seat. You have to prize open the outer case tabs to get access to the motor and gearbox. It's that thread you will find details and pictures of the gear train. The EGR faults are derived from detected anomalies in air flow but also there is a position sensor I believe in the EGR itself but I've yet to find details of that. The other 3 pins in the connector I assume are to do with that. The opening position of the EGR valve is controlled using a variable pulse width control signal from the ECU, you need an oscilloscope to look at the signal. I'll try and post something on it so members who are interested can get more knowledge. I believe the sensor is a non contact hall effect type that measures the magnetic flux or reluctance change as the large gear rotates. I'll try and find out more. I'd like to get hold of more example EGR valves as I think most are serviceable. "You are never to old to learn something new" |
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21st Sep 2017 8:36pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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This is the link for the Torque App about 4 quid. http://www.androidauthority.com/torque-app...bd2-95772/ Here is a link for the bluetooth OBD2 Scanner plug in unit. https://www.ebay.co.uk/sch/i.html?_from=R4...p;_sacat=0 There are loads of these on ebay so if the link fails with time just search OBD2 scan and you will find one. I had to cut away a bit of the plastic trim above the accelerator pedal where the OBD connector is located as there was not quite enough room to fit the bluetooth OBD2 plug. I leave it in place all the time. The chugga chugga or chukka chukka is the sound that "most" EGR valves make a few seconds after turning off the engine when it is put into its cleaning sequence. If it's dead quite then it's either a perfectly manufactured example or its not working. If you want to amplify it, stick a long screw driver on it, listen with the handle in your ear and get someone to turn off the engine. "You are never to old to learn something new" |
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21st Sep 2017 9:01pm |
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| custom90 Member Since: 21 Jan 2010 Location: South West, England. Posts: 19578
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The 'chugga, chugga' sound is the EGR self cleaning cycle that happens just immediately after engine shut down.
If you have a remap with the EGR shut down, this can be disabled as well or cleaning cycle operational only but still electronically blanked shut. I decided to have mine shut, and the EGR cleaning cycle turned off also. Diesel$ Live$ Matter. ⛽️🛢️👨🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧 |
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21st Sep 2017 9:28pm |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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Do you have to inform your insurers if you have the EGR effectively turned off by a change to tge ECU even though it doesn't make much difference to performance? "You are never to old to learn something new"
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21st Sep 2017 11:12pm |
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| OleDave Member Since: 19 Oct 2013 Location: CARDIFF Posts: 175
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Hi B4lamb and guys, many thanks for the info B4lamb, I sorta guessed the valve would have a variable control depending on the conditions, Ah! I now understand what your saying the chugga chugga from the valve when the ignition is turned off, will have to get the wife primed one day soon when its not raining and listen to the valve working (Or Not) and make a decision on whether to strip or replace, obviously replace is the easiest of the options for me but the most expensive as I have checked LR and they are around 190 plus vat.
In conclusion on the issue again of EGR problems, I was advised by my garage that they have a useful chap who is a good all rounder in the control department that they use from time to time, it appears he can blank out the ECU from seeing the EGR valve altogether plus stop the Engine management light showing if disconnected, but I am am worried that doing that might cause other problems, what are all your thoughts on blanking off the EGR system and letting the engine breath constant fresh air? Have looked at your link and will get an OBD2 adaptor and the App soon as it looks a useful tool to have, many thanks for the lead on that, it would be very interesting maybe one day to meet up with you for a general chat re: the defender, we occasionally visit the Brecon Beacons Caravan club site outside Brecon as its only 50mins from where we live, maybe the next time we are up there and if your free we could meet up for a chin wag and a coffee? Regards Ole Dave |
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22nd Sep 2017 8:46am |
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| blackwolf Member Since: 03 Nov 2009 Location: South West England Posts: 16879
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Yes, it's a modification and you are contractually required to tell them. Your policy could be invalidated if you do not. That being said, I doubt that many people do. It is hard to see how it alters the risk, and how would the insurer know if the EGR was working or not? |
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22nd Sep 2017 10:34am |
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| B4Lamb Member Since: 21 Mar 2015 Location: Abergavenny, Wales Posts: 233
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There are conflicting opinions on blanking or disabling the EGR function. Some say that reducing the combustion temperature that produces the Noxious Nitrogen Oxide (NOx) that the EGR function is designed to reduce in the emissions has a beneficial effect to engine life and while others that I tend to side with say that allowing carbon deposits back into cylinders has a negative effect of wear in the cylinder bores and degradation (blackening) of the engine oil as well as the build up of soot and tar in the inlet manifold and vacuum tubes. There is a good article on the subject in Wikipedia worth reading https://en.wikipedia.org/wiki/Exhaust_gas_recirculation "You are never to old to learn something new" |
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22nd Sep 2017 1:19pm |
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| OleDave Member Since: 19 Oct 2013 Location: CARDIFF Posts: 175
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Hi 4Blamb and guys, On the topic again of EGR valves, I have just come back after a trip out shopping so the Defender engine was up to temp, I pinched the wife's stethascope which she uses during clinics for patients
 I had her turn off the engine while I did a listen to the EGR valve operation, it does exactly what you mentioned and does the chugga chugga although to my hearing it sounds more like a hen scratching around in the dirt 4 times lol.
If that signals its going through its cleaning cycle and working I am confused why on the garage computer it shows up a faulty EGR valve, I suppose that could mean a number of things such as the valve bypassing gasses, not fully opening or fully closing? any suggestions? Regards and many thanks Ole Dave |
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24th Sep 2017 11:49am |
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