Diesel Engine Fault
Posted 30 June 2009 - 10:08 AM
Recently the ĎEngine Faultí light came on a couple of times within a few days so took it to main dealer. They:
Carried out proxima test, found temp fault, turbo pressure signalí. Round test and erase, customer to monitor.
Light came on again a few days later so back to main dealer and they:
Replaced turbo electro valve and erase faults & road test. Fit VAC Solenoid.
On the same day my wife filled up with supermarket diesel (as usual).
Next day car was awful seemed to be losing power just for a second or two but doing so every couple of miles. Back to main dealer.
They said nothing they had done would have caused this problem but tested anyway and found no faults. Recommended if it happens again it will need a new turbo @ £1000. Lost confidence in main dealer.
After engine fault light came on again I took it to an independent Citroen specialist and he found:
Permanent fault turbo pressure signal, high pressure raw signal. Fitted new turbo pressure sensor and cleared the fault.
Better, but not 100% for next couple of weeks, then same problem returned with brief but regular misfire/power loss, especially during gentle acceleration up slight hills. Engine fault light also coming on. Back to independent.
Same fault found turbo pressure high. He suggested either a wiring fault or fuel problem. As I use mainly supermarket diesel he said to run down tank and fill up from normal garage to see if better fuel would solve problem. He is also going to fit new fuel filter.
Turbo seems to be working ok, if I put my foot down I get good acceleration. No problems apparent at tickover.
Thatís where I am at the moment and I am due to go on a motoring holiday next month. Anyone have any ideas? I'm sure its related to the first fix or refuelling as problem did not exist day before but did day after.
Thanks in advance
Posted 30 June 2009 - 11:45 AM
Posted 30 June 2009 - 02:43 PM
Posted 30 June 2009 - 03:07 PM
Having a similar problem with my Picasso 1.6HDI, just bought 1 and a half weeks ago from a second hand dealer and still under their guarantee. Seems to lose power for a second when accelerating and then the engine management light comes on. Had it back to the dealer twice and at first they just cleared the fault then after they replaced the turbo sensor but it came back again. It just disappears after a day again making it really hard to diagnose. The fault has been accompanied by alot of squealing from the brakes whilst driving at low speed although I am not sure whether this is related.
I am wondering if it is the stock fault:
The vehicles concerned have been fitted with a fuel injection high-pressure sensor harness
connector, which has unsatisfactory crimping. This failure could cause the engine
diagnostic light to come on.
You would think the Citroen Dealers would be aware if it is this fault but not sure how to check if it applies to my model.
Hoping for some insight.
Posted 30 June 2009 - 03:38 PM
When you are on a decent 'A' Road try keeping your speed at a constant 40 / 50mph whatever you can do, see if theres any noticable sounds to the engine especially if you go up a slight incline (not hill)?
Hi Joe, haven't heard anything untoward but I will check it again tonight.
Posted 30 June 2009 - 03:43 PM
Sounds odd i know but have you got too much oil in your engine? too much oil pressure can give false readings to the turbo pressure sensor.
Hi, yes I've checked the oil, its just below the full level.
Posted 30 June 2009 - 05:58 PM
Posted 01 July 2009 - 12:14 PM
I believe after replacing the sensor and it happening again my dealer pressure tested the turbo, in my case the turbo was replaced. (March 2006 1.6hdi @ December 2008 - 44,265 miles).
Posted 01 July 2009 - 03:50 PM
Posted 02 July 2009 - 07:36 AM
I'm wondering, as it happen the day after the main dealer replaced the turbo electro valve, whether any hoses or whatever were not tightened up properly allowing air to get in. (if in fact this task required hose removal or loosening)
Clutching at straws now I think. I have no knowledge of the workings of the modern diesel engine so just guessing really.
Posted 02 July 2009 - 10:37 PM
I have been trying for months to locate it.
Sometimes it occurs sometimes it doesnt.
Sometimes it will stall, sometimes it will start again, other times it seems as thouigh it has to cool down a wee bit before it will start....though this has only once or twice.
Most times is just the 'stumbling' you describe.
NO warning lights and \the ponly fault in the ECU recorded was an imobiliser fault that we couldnt clear.
Keep me updated.
Posted 03 July 2009 - 07:37 AM
Posted 03 July 2009 - 08:02 AM
Posted 03 July 2009 - 06:10 PM
Posted 03 July 2009 - 08:23 PM
You could try these?
All turbo cars are affected by high ambient temperatures.
The inlet air temp is higher, meaning that the air is less dense - so the turbo has to work harder to compress this air and produce the required boost. But because the air is worked harder, it leaves the turbo hotter, so the intercooler has to do more work, yet it has less dense/cool air to exchange this hotter charge air into. A harder-working turbo compressor also risks getting outside the optimum efficiency range, heating up the charge even more. And when the intercooler does manage to shed some heat, it just ends up in the engine bay, preheating everything even more.
That's why turbo cars suffer a double whammy with regards to performance compared to normally aspirated engines.
Posted 03 July 2009 - 10:08 PM
The turbo is 'driven' by exhaust gasses and is a part of the exhaust system, therefore it will ALLWAYS be at the temperature of the engine exhaust gasses..........which change with engine speed.
An intercooler is simply an air to air heat exchanger, when the car is moving its getting sufficiently cooled....we are not a hot country and so it will barely make a difference.
My thoughts have always been the ecu coolant temp sensor, accelerator position sensor or perhaps EGR valve that are faulty.
As above my turbo works perfectly, it can be heard spooling and can be felt operating...no funny noises and would certainly not make the car stall.
In fact when my car plays up I find harsh acceleration gets rid of the 'stumbling'.
Someone did post to check the low pressure fuel pump relay....I did ask where it was but go no reply.
Posted 05 July 2009 - 06:19 PM
My money's on a faulty Turbo! At least if a dealer pressure tests it and you'll know one way or the other
You could try these?
Hi Joe, thanks for the tips. You have probably gathered I don't know much about modern engines and less about diesels. As far as I can tell my car suffers none of the turbo problems in the dignostic chart. I am seeing my independant specialist next week and he is going to fit a new fuel filter (process of elimination really). I'll ask him if he can pressure test the turbo as you suggest. The sensor is showing fault 'turbo pressure high'. How does the pressure test diagnose a turbo please?
Posted 05 July 2009 - 06:21 PM
Thanks crossy, I will show your tips to my independant specialist next week.