| Home  Blogs Help Search Login Register  
« previous next »
Pages: [1] Print
Author Topic: Loss of power - temporarily  (Read 6116 times)
TheJoker
Sr. Member
****
Posts: 278


WWW
« on: October 06, 2006, 01:42:47 pm »

Gents,

On my way into work today I got a bit of a dent in my building confidence in the Espace.

This is what happened.
I started Big Bertha up and rolled away gently. At the first T-junction I stalled (was sleeping with 2nd in gear, trying to pull away - d'Oh!). I restarted and carried on. The car felt slow, but I didn't bother much. After a while the car beeped at me... Then it showed that "wavy" diagnostic image (where it usually says "OK"), and the ABS warning light came on. At a traffic light I turned the engine off, and restarted (Microsoft..?) The warnings went away, and I took it very steadily.
Then at the dual carriage way the car felt extremely gutless. I was doing 65mph with the throttle pinned to the floor in 4th and it just did not want to increaste. It took a very long time before I reached 70mph...
I then stopped at a roundabout off the dual carriage way and suddenly the power was there - cruising at *cough*nine*cough*ty*cough* mph was no problems....

... Should I worry??  Huh  Roll Eyes  Shocked
Logged

Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
Will Falconer
Sr. Member
****
Posts: 161


« Reply #1 on: October 06, 2006, 03:16:23 pm »

I don't know nothin about diesels, but the good news is that the wavy line coming up shows that the fault is registered and can be queried by a diagnostic computer. I think some faults require a Renault diagnosis but most can be read by any diagnostic computer.
Logged
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #2 on: October 06, 2006, 03:19:24 pm »

Good point, Will. Cheers!  Cool
Logged

Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
Anders Dinsen
Administrator
YaBB God
*****
Posts: 2823



WWW
« Reply #3 on: October 06, 2006, 03:41:25 pm »

... Should I worry??  Huh  Roll Eyes  Shocked

Only about getting caught by a speed trap Cheesy haha

No, really this is one of those on-off-problems that will only follow Murphys Law - they will popup whenever it's most inconvenient. As both ABS *and* engine diagnostic showed problems, chances are it's a loose connection somewhere. Leave it for now, see if it pops up again, and when it starts becoming annoying, go to Renault and have it diagnosed.

Cheers,
Anders
Logged

'82 Murena 2.2 prep 142
'01 Grand Espace 24v
'08 Smart Fortwo 0,8 cdi
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #4 on: October 06, 2006, 03:42:56 pm »

Good point Anders, very pragmatic. I like that!  Cool  Grin
Logged

Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
Martin Tyas
Sr. Member
****
Posts: 271


Espace, because it's worth it!


« Reply #5 on: October 07, 2006, 12:33:30 pm »

You experienced your car having an ďasthma attackĒ.... or more commonly referred to as a problem with the EGR valve. It isnít a loose connection.... trust me on this one.... but Anders is right on one point, it will happen again and probably at the most inconvenient moment but I will in any case attempt to explain.

First, please indulge me whilst I try to explain what the EGR valve is and what it is supposed to do. Forgive me if you already know.
EGR is the acronym for Exhaust Gas Recirculation. The basic function of the valve is to reduce NOx (oxides of Nitrogen) emissions. You may have seen or read reference to Euro III and IV standards for diesel engines and it is the control of NOx that is the main driving force behind moving through the ever tightening standards for exhaust gas emissions as Euro III standards evolve through to Euro IV by the end of 2006. Most manufacturers are having now to tackle the further reduction of NOx by exhaust after-treatments but the problem was first addressed by the introduction of the EGR valve that was first developed over 30 years ago. Early EGR's were vacuum actuated but are now electronically controlled. When an engine is under load the resultant very high combustion chamber temperatures increase the amount of NOx in exhaust emissions. The problem was how to reduce it and one solution was the EGR valve which allows some carbon dioxide to be introduced into the combustion chambers as a "coolant" gas. The valve is designed to open and close by varying amounts dependent upon engine speed and load but it can get sticky or even completely stuck due to carbon deposits. If it becomes stuck open the engine suffers from reduced power from having too much carbon dioxide introduced into fuel/air mixture and therefore insufficient oxygen to provide adequate combustion. If the valve gets stuck closed then the combustion chamber temperatures would rise under load and you would get "knocking".  A potential added and more serious (read expensive) consequence of the EGR valve being stuck closed on turbo charged engines is that if run continuously under load the resultant higher combustion chamber (and therefore exhaust gas) temperatures could reduce the effectiveness of the lubricant in the bearings of the turbo charger (which is driven by exhaust gases) due to the excess heat and cause premature failure.

Sticking of the EGR valve usually occurs when the engine is under heaviest load at low revs such as when you are pulling away from standstill, when trying to accelerate (especially up an incline) and I have had it happen with my Espace at 70mph in top gear on the motorway as I came to a long steady gradient. Diesel's in general, and the 2.2dCi is a good example, have good torque characteristics and lugging ability.... one of the main reasons diesel engines are used in tractors, construction equipment and trucks and so you would assume that they would easily pull away under load and at low revs.... well they will.... BUT.... remember that the EGR sometimes doesn't like it and that maximum torque occurs at 2000 rpm on this engine. When under load the engine draws in more air (and fuel) and just like a human being that is gasping for breath there is a tendency for the crud in the windpipes to dislodge (I'm trying not to be too graphic in my description of the outcome of having a chesty cough!!).... and just the same with a vehicle engine gasping for air when itís under load it tends to dislodge the crud in itís windpipes, or to be more precise, the particles of carbon in the manifold. If large enough these particles can wedge themselves in one or both of the two diaphragms in the EGR valve not allowing it to fully close. Hence the reason for describing what you experienced as being like your car having an asthma attack... an allergic reaction to you having set off in second gear and loaded the engine at too low revs.

Because the diaphragms cannot fully close due to the carbon particles you get a lack of power and a complete lack of responsiveness due to the excess of carbon dioxide being introduced into the combustion chambers and resultant lack of oxygen as previously described. The valve is actuated by a solenoid. That is a coil winding which, with an electric current applied to it, creates a magnetic field that then moves the valve.... the position of the valve is controlled by the amount of current passed through the coil. The more current that is passed through it the greater the magnetic field resulting in a greater movement of the valve. By turning off the engine the solenoid is de-energised and then re-energised when the engine is re-started. This action quite often allows sufficient movement of the valve diaphragms to allow the carbon particles that are wedging them open to fall out and your problem is solved..... as happened with your car this time. But it is likely to occur again and when it does and you canít clear it by turning off and restarting the engine you could always take it (as others have suggested) to a Renault dealer who will charge you for plugging it in to their "magic box" only to be told that the computer says it is the EGR valve. The chances are that they will then also charge you 150 GBP for a new one plus labour for fitting it when, in most cases, it can quite easily be removed, cleaned of carbon from the diaphragms and valve shaft, then re-fitted.

I've attached a photograph of the location of the valve in the manifold immediately below the air filter housing. I've circled two of the three mounting bolts... you can guess where the third one is!!
When I experienced the first "asthma attack" and didn't know what caused it, I called the AA for roadside assistance whilst it was in warranty and part of the customer care package. The second time I knew what the problem was so did it myself and the valve was removed much more easily... the AA man must have needed a bolt for another job as he only put back in the two that were visible and took with him the one that was fairly inaccessible!!!.... but to be honest I have not since replaced it. To remove the electrical connector insert a flat bladed screwdriver into the slot arrowed on the photograph and lever it over slightly to the left to release the retainer whilst at the same time pulling up the connector. Don't insert the screwdriver too far into the slot otherwise you can't release the retainer. Only as deep as the slot, about 3 to 4mm.
With the 3 bolts (or 2 as the case may be) and the electrical connector removed the valve body can be withdrawn from the manifold for cleaning... then the easy part according to what the manuals always say... because "refitting is a reversal of removal".

However, you should also remember that you are now driving a Matra.... despite it having a Renault engine, a Renault badge (and a few other not insignificant Renault components) it was designed by Matra engineers who try to think of everything. So if you don't want to utilise the storage compartment below the driverís seat for a fire extinguisher, as I suggested the other evening, then you can always use it to store your replacement EGR kit... comprising a replacement EGR valve, a 10mm spanner (if you only have two bolts you don't need a socket and drive extension), a flat blade screwdriver, a pair of latex gloves (in case next time the problem occurs when you are in your best clothes) plus a cloth to clean the re-useable steel gasket... and if you retain the box from the new valve then Renault have very thoughtfully made it big enough for you to store all of your other kit items along with the valve. However if you already use the under-seat compartment for a fire extinguisher then the very thoughtful Matra engineers have given you an alternative storage compartment for your EGR kit in the right hand side of the luggage compartment opposite the CD Changer. You can also do your bit for recycling... re-use cloth you used to clean the steel gasket to wrap the carbon coated and oily EGR valve that you've removed and use the box to store it until you get home and have time to remove the carbon, clean it up and recycle the original valve into your kit ready for the next time it happens.

But seriously, you will grow to love, enjoy and wonder however you got through life before without such a vehicle as "Big Bertha" as you call it... and this will come as you adapt your driving style to suit it... trust me on this point also.... and if there is one piece of advice regarding adapting your driving style that I would urge you to take and that is not to allow the 2.2dCi to labour at low revs.... donít attempt to pull away from a junction in second gear even though you may already be rolling... drop down a gear when you start to feel the revs dropping under load... drive in a 30mph zone in third if necessary... in other words use the gears more than you thought you would have to with a vehicle that has a 2.2 turbo diesel putting out 130 horse power... just remember itís heavy even without the pilot and 6 passengers (or girlfriend and 2 motorbikes) and despite having a very good engine the maximum horse power comes at 4000 rpm and max torque at 2000 rpm so remember that and donít have it gasping for breath under load at low revs. In nearly 4 years and almost 70,000 miles the EGR has stuck a dozen or more times on my Espace.... and EVERY time it occurred was when Iíd loaded the engine at low revs.
Other things that can help to avoid problems with the EGR are the use of good quality synthetic engine oil that will help to reduce the carbon build up and also ensuring that the air filter is changed at the prescribed service interval or sooner so that when the engine does need air it can get it without risking another asthma attack and coughing carbon deposits straight into the EGR valve.

Here endeth the lesson on EGR's Wink

Martin
« Last Edit: October 07, 2006, 01:01:18 pm by Martin Tyas » Logged

1968 Cessna 182L Skylane
1991 BMW 520i SE Auto
2002 Grand Espace 2.2dCi "The Race"
2003 Astra 1.8i Cabriolet "Edition 100"
2011 Insignia SRi VX-Line Red
2011 Honda VT1300CX Fury
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #6 on: October 07, 2006, 03:54:08 pm »

Martin, you're a star! What a fantastic reply!!  Thank you very very much! I'll have a look in a bit to look at the valve to, at least, familiarize myself with its location... for when it happens again (note, "when", not "if" ahhah).
Also thanks for the tip of not loading the engine at low revs. I've started driving the car in fairly low revs because of its torque, but I'll give her a bit more revs from now on...

Fantastic!  Cool  Thanks!!
Logged

Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
Lennart Sorth
Administrator
YaBB God
*****
Posts: 818



WWW
« Reply #7 on: October 07, 2006, 05:41:49 pm »

Thanks to Martin for a GREAT post. IF there was an award for the most elaborate post, this one certainly is a strong contender :-)

I have never had serious problems with my EGR, - but sometimes the car may feel a bit down on power. When this has happened, I use the advice of MECUK president and former Renault mechanic:

Put the car in second gear, and run for a while on the revlimiter (govenor) - this will probably emit an impresive cloud of smoke from the exhaust pipe, but it should soon subside,and become transparent.  The EGR is now ready for another stint.
Remember to do this when nobody are driving just behind you, as they will probably think your car is about to explode or something :-)

Of course, if the EGR is still stuck (hasn't happened to me yet), then you will have to go through the dirty job.

/Lennart
Logged

Lennart.Sorth@matrasport.dk
Murena 1983 1.9i silver // Alfa Romeo Giulietta 2.0d 2012 white // Smart 4two cdi 2010 blue //
TheJoker
Sr. Member
****
Posts: 278


WWW
« Reply #8 on: October 07, 2006, 06:05:51 pm »

Another great tip! What a useful forum this is! Smiley
Logged

Grand Espace 2.2 dCi 2001 Silver
KTM 990 SuperDuke R Smiley
Dead: BMW K1200R
Pages: [1] Print 
« previous next »
Jump to: