RayFi Posted November 8, 2023 Share Posted November 8, 2023 Dear Community, Turning here for help. My engine is idling normally, but approx. every minute, it briefly revs up for a second (or even less than a second) before returning to normal. This is happening both after cold starts or warmed up, no difference. Also noticed at highway speeds, very occasionally the engine stalls for a very brief moment but only when the engine pulls either at higher speeds or when climbing, but again, this is very rare not like the idle revving. Scanner read fault code P0638 related to throttle body. It was disassembled, found to be still the original Wahler, flap was not returning firmly, throttle body was replaced to a Pierburg. Did not solve the problem. Alternator charges with 14.1-14.2V, the momentary rev up does not have effect on it, I would rule out an electric appliance trying to pull energy Intake manifold where the throttle body was fitted had quite some dust, it was also cleaned up I was recommended to pull out all injectors for testing but not too happy throwing more money on this without understanding the root cause of the problem. 2007 Ducato 3.0 160 Multijet Linked a sound file, the revving can be heard at 0:30 and at 1:30. https://www.dropbox.com/scl/fi/junhvo4kv11yvqr3v8gxo/ducato_idle_kick.mp3?rlkey=u5c899sc300msv8tqfy4lsqx2&dl=0 Any help appreciated. Quote Link to comment Share on other sites More sharing options...
onecal Posted November 8, 2023 Share Posted November 8, 2023 Hi, Have you an air con pump ? Regards Quote Link to comment Share on other sites More sharing options...
RayFi Posted November 9, 2023 Author Share Posted November 9, 2023 You mean air condition? Yes I do. I tested switching aircon on/off, no impact. Quote Link to comment Share on other sites More sharing options...
Labby Posted November 9, 2023 Share Posted November 9, 2023 (edited) Have a look at www.aandncaravanservices.co.uk the varying idle speed fault on Fiat Ducatos is described , with the engine to body earth cable connection (resistance ) found to being the cause , which may be the fault in your case . Edited November 9, 2023 by Labby 1 Quote Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 9, 2023 Share Posted November 9, 2023 This link is to the relevant section of the website Labby has mentioned. https://www.aandncaravanservices.co.uk/earth-strap-problems.php The 'earth strap' goes between the gearbox and chassis. It's referred to here https://www.fiatforum.com/threads/earth-strap-lead-2012-3-0.358832/ and is normally straightforward to replace. Replacement of the earth strap is not a panacea, but it's a cheap/simple task and - if a Ducato motor starts behaving peculiarly - it's worth trying before more expensive remedial measures are taken. 1 Quote Link to comment Share on other sites More sharing options...
RayFi Posted November 9, 2023 Author Share Posted November 9, 2023 Thank you all, will give it a check and voltage measure. Is it going to be enough to detach the neg lead of the battery when working on it or is it needed at all to disconnect battery? Quote Link to comment Share on other sites More sharing options...
rayc Posted November 9, 2023 Share Posted November 9, 2023 23 minutes ago, RayFi said: Thank you all, will give it a check and voltage measure. Is it going to be enough to detach the neg lead of the battery when working on it or is it needed at all to disconnect battery? Connect a jump start cable between the gearbox casing and the chassis and see what happens. No need to disconnect battery whilst doing so. 1 Quote Link to comment Share on other sites More sharing options...
onecal Posted November 9, 2023 Share Posted November 9, 2023 (edited) Hi OK If the air con pump (ACP) has no effect and you have checked all the usual fuel filter/air filter change etc' and as Derek /Labby/ rayc suggests , with no effect? , check all connections to the injectors and ECU and throttle body wiring and connections. Pay particular attention to the throttle body connection pins and fuel filter and associate pipework for leakage/air ingress. Was the new Throttle Body calibrated on fitting ? Check also all the vacuum lines and do a smoke test see if you find any leaks .Did the fault code P0638 stay cleared ? Regards Edited November 9, 2023 by onecal Quote Link to comment Share on other sites More sharing options...
colin Posted November 9, 2023 Share Posted November 9, 2023 OK, time for my stock answer. Have you checked for mice in the inlet? 1 Quote Link to comment Share on other sites More sharing options...
RayFi Posted November 9, 2023 Author Share Posted November 9, 2023 4 hours ago, onecal said: Hi OK If the air con pump (ACP) has no effect and you have checked all the usual fuel filter/air filter change etc' and as Derek /Labby/ rayc suggests , with no effect? , check all connections to the injectors and ECU and throttle body wiring and connections. Pay particular attention to the throttle body connection pins and fuel filter and associate pipework for leakage/air ingress. Was the new Throttle Body calibrated on fitting ? Check also all the vacuum lines and do a smoke test see if you find any leaks .Did the fault code P0638 stay cleared ? Regards Aircon pump has no effect, airfilter checked, was fitted 5.000km ago. Fuel filter replaced for new. i will need to check closer the wiring and piping. Throttle body had no calibration, how to do that? It was just fitted with the new adapter cable to the old wiring and new gasket but just plug and play. Van runs much smoother, easier acceleration, better in all aspect but the annoying minirevs every minute stayed on. Fault code disappeared. Quote Link to comment Share on other sites More sharing options...
RayFi Posted November 9, 2023 Author Share Posted November 9, 2023 3 hours ago, colin said: OK, time for my stock answer. Have you checked for mice in the inlet? Haha what? 😁Which inlet? This is going to be more fun than I thought. Quote Link to comment Share on other sites More sharing options...
Keithl Posted November 9, 2023 Share Posted November 9, 2023 1 minute ago, RayFi said: Haha what? 😁Which inlet? This is going to be more fun than I thought. Fresh air into the air filter. Quote Link to comment Share on other sites More sharing options...
onecal Posted November 10, 2023 Share Posted November 10, 2023 Hi They may all need to be re checked as advised epically the wiring and associate piping and vacuum lines You do not say when this started or was it present from new? or from when you purchased the motorhome Did this happen after an update to the ECU or a remap? Regards Quote Link to comment Share on other sites More sharing options...
Derek Uzzell Posted November 10, 2023 Share Posted November 10, 2023 9 hours ago, RayFi said: Haha what? 😁Which inlet? This is going to be more fun than I thought. In the past there have been several motorhome forum reports about mice entering a 2006-onwards Ducato's air intake and finding their way into the plastic housing that encloses the air-filter. Sometimes the hungry mouse chews its way through the filter, allowing it to travel further towards the motor itself; while, in one reported case a desperate sharp-toothed rodent managed to chew right through the wall of the plastic housing. When the the mouse dies, the likelihood is that its body, plus any damage it has caused, will affect (sometimes badly affect) how the Ducato's motor will run. The mouse problem and preventive measures were discussed here in 2021 https://forums.outandaboutlive.co.uk/topic/52018-fiat-ducato-motorhome-mice-in-air-filter/ (Although your 'revving' issue doesn't sound like it's mouse-related, it should be a simple matter to check that the air-filter and its housing are undamaged.) Quote Link to comment Share on other sites More sharing options...
colin Posted November 10, 2023 Share Posted November 10, 2023 10 hours ago, RayFi said: Haha what? 😁Which inlet? This is going to be more fun than I thought. For many x250/290 owners it has been no fun, it took thousands of miles and over a thousand pounds to find the problem in my van, someone else had a wreaked engine due to a bodged repair after mice in the filter housing. Quote Link to comment Share on other sites More sharing options...
RayFi Posted November 10, 2023 Author Share Posted November 10, 2023 (edited) Thank you all. I did mean “ fun” in quotes actually, I can see myself the ignorant jobs my van had suffered in the past and rather would be crying than laughing. Windscreen drain plastics had only one holder installed, water poured all the way down to engine bay. Now fitted a plastic engine bay shield to repell water away from the injectors. I purchased it with the revving issue present and have no history on it. Regarding the mice issue I can definitely confirm mine is clean, I had the filter which is a wire mesh one inside not the default paper only removed, visually inspected, tubes, airflow sensor and housing cleaned before reinstalling. Edited November 10, 2023 by RayFi Quote Link to comment Share on other sites More sharing options...
Tracker Posted November 10, 2023 Share Posted November 10, 2023 It is probably not the issue here, but in the old days temporary surging of a diesel engine at idle was often caused by the ingress of air into the high pressure side of the injection system and was more often than not cured by bleeding the injectors and tightening all the unions. But that was then when engines were simple mechanical machines uninfected by the scourge of electronics and pollution malarkey. Progress eh? 1 Quote Link to comment Share on other sites More sharing options...
onecal Posted November 10, 2023 Share Posted November 10, 2023 (edited) Hi Tracker Still the same and one thing one always should check paying special attention to the fuel filter and lines .Yes modern wiring looms and connections throttle bodies do give lot of trouble especially the looms if chaffed or pulled and not very fond of water ingress anywhere close to their connections. As to mice infestation , they really destroy everything I would also check out for a faulty injector or input and also the fuel pump . As the OP now informs us this problem existed from his purchase and he has no history of the fault at all I think maybe a good mechanic is required to do a full check on it , it's not an intermittent fault as the OP also informs us it's there during hot/cold idle, so I assume he has tried all the wiggle tests on the wiring to see if any change Also replaced with new earth wires (not just clean them , but cleaned the connection points) Maybe also a check to see if an update or remap was carried out also at some point . Regards Edited November 10, 2023 by onecal Quote Link to comment Share on other sites More sharing options...
RayFi Posted November 13, 2023 Author Share Posted November 13, 2023 Quick update: check engine came on, although no other evidenced behaviour. Have arranged a mechanic visit for next week for a diagnosis, will report back. Thanks for you all for the supportive comments. Quote Link to comment Share on other sites More sharing options...
onecal Posted November 14, 2023 Share Posted November 14, 2023 Keep us informed 1 Quote Link to comment Share on other sites More sharing options...
RayFi Posted December 4, 2023 Author Share Posted December 4, 2023 Back from the mechanic, the EGR was "blinded" but apparently the vacuum piping was not properly attached and they told me that the computer was not instructed to forget that the EGR was not working, plus the EGR controller solenoid was faulty, that needed a replacement. Now with EGR working, correct piping, all work as it should, solenoid kicks in just about a minute after idling. Earth strap was replaced as well due to its oxidized look. Thank you once again for all your support and suggestions. Quote Link to comment Share on other sites More sharing options...
onecal Posted December 4, 2023 Share Posted December 4, 2023 Hi So there was a re map at some point and maybe some poor work carried out Regards Quote Link to comment Share on other sites More sharing options...
RayFi Posted December 4, 2023 Author Share Posted December 4, 2023 Remap not sure, botched job definitely. Quote Link to comment Share on other sites More sharing options...
onecal Posted December 4, 2023 Share Posted December 4, 2023 (edited) Hi Yes disconnecting vac' piping etc not a good idea You say EGR V/V "blinded" Do you mean completely blocked or was it mapped out ? Or maybe someone tried to map it out as with the other botched as you say work on the vehicle Glad you have solved your problem Regards Edited December 4, 2023 by onecal 1 Quote Link to comment Share on other sites More sharing options...
RayFi Posted December 10, 2023 Author Share Posted December 10, 2023 On 04/12/2023 at 17:51, onecal said: You say EGR V/V "blinded" Do you mean completely blocked or was it mapped out ? Or maybe someone tried to map it out as with the other botched as you say work on the vehicle Glad you have solved your problem From what I understood happened is the EGR valve was simply blocked with a blind pipe and in fact having it not mapped out in the computer triggered the fault code. So now with no software modification the expected EGR operation was restored including a replaced EGR solenoid and properly run pipes between the solenoid and the EGR. I can actually hear on idling for a while when the EGR opens (idling tone gets slightly deeper). A full diag was run after a couple of hundred miles and now no issues, no temporary codes. Injector comp values were also checked and they are very close to 0 with slight variations but equaling out to zero. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.