Engine cutting out very briefly.

[triumph2.5man]

Hi folks, our 1.5dci dynamique 2003 is still chugging along, now approaching 95k miles. However a new problem is on the horizon - intermittent at the moment. Does the following description mean anything to anybody? Have you come across this? Daughter reports that from time to time the engine appears to hold back for a second or less as if she has dabbed the brake pedal, then continues to run as normal. To begin with she thought she was in a gear that was too high but this seems unlikely. The engine does not stall and no messages appear on the display; no warning lights come on. How often does this happen? Most mileage is urban and the problem might arise once a week or less. On a recent, fast 400 mile journey, it happened once only. I rarely drive the car and have yet to experience the problem and don't really know where to start. Seems to me it is almost as if the ignition has been switched off then on again. Ignition switch fault? I came across this on other makes yonks ago but seems unlikely in this instance as these cars do not have a conventional ignition switch.Car always starts first time even in extreme cold, and runs well. At idle speed I do sense that the engine is not quite so smooth as it used to be - there is a distinct, but mild shake detectable in the car body. May or may not be relevant.
At present I am doing the usual - waiting for the intermittent fault to become permanent - as long as it does not happen at 70 in the outside lane of the M25!
Any ideas folks? I promise to keep you informed of any developments....(I wish more members did!)
Mike

[AlexB]

There were a few reports ages ago about 1.9dci doing this when pulling off at traffic lights. I experienced this several times as well. Then you just release the accelerator and press again - it goes. I don't think the cause was found. My car suddenly stopped doing this, which may be related to cleaning the EGR valve, or fiddling with some connectors.

Does it happen at a steady speed or when pulling off?

[triumph2.5man]

thanks for the response Alex. Good question! It seems to happen at a steady speed (but more observations will be noted the next time it happens!) It has happened once this week at 30mph in third or top. Clearly it is not going to magically clear up by itself! I was thinking on the lines of rheostat problems in the accelerator pedal. I know that the Mondeo TDCI tracks in the "fly by wire system", can wear, resulting in inaccurate TPS info (throttle positioning sensor). I will be interested to know if anybody has dissected a Megane throttle sender unit.
Mike

[wucash]

Hi there,
Mike! Did you manage to sort this problem out yet? My megane 1.9 dci does excactly same thing. No faults on Computer check either. NOTICE... it doesnt happen on cold engine. It looks like it starts after it worms up a bit. We have cleaned the EGR valve and "piping" around it and nothing helps. Would be greatful for any help.
Lukas

[triumph2.5man]

Sorry for delay in replying. No have not solved the problem yet but I'm glad to see somebody else has it!
This has been going on for about 5 months. At one point it seemed to decrease, then returned as before.
During a fast 200 mile run last week, the fault did not occur at all on the outward journey. But during the return 200 miles, it happened 4 times. I have yet to experience the problem but was a passenger on one occasion when it held back but i did not notice anything untoward. You have to be driving to experience it. More worrying is the fact that daughter announced today that the car gave its worst (or strongest) "hold back" todate. it still did not stall though. All very mysterious. You could be correct about happening only when engine is hot - I will seek advice. One thing at a time though as I have other more-pressing problems to solve with this car!
Mike

[tomalamix]

EGR fault will on be registered and / or displayed on the dash if it persist for more then a few seconds...the stall is for more then a few seconds? or is only 2 seconds and then of it goes?

there is the possibility of an injector going its way out or fuel lines letting air go inside..

[VroomVroomClonk]

Hello. Yes, I have exactly the same problem with a 1.9DCi 120bhp, from 2004. I've owned the car for about 4 months (8,000 ish miles), and it has probably only had the problem 6 or 8 times during that period. When it happens, it is rare enough that it is hard to realise straight away and actually take note of the exact symptoms. But, it certainly never stalls completely, the hold-back seems to last for about 1 second, and it always seems to run absolutely fine at all other times. As long as it doesn't get any worse I can live with it, but it is annoying. Also, I'm taking the car abroad in a few weeks time, and I really don't want it to die on me completely then! Any suggestions would be very welcome please.
I should probably add that the car has done 98,000 miles, has a full service history and is showing no error codes on a CLIP.

[VroomVroomClonk]

Well, after almost exactly 2 months of this not happening again at all, it has now done it twice in a couple of days.

[triumph2.5man]

Hi V V C! Sorry to hear about your problem. That is 3 meg2 drivers (at least) with this problem. There must be others. I never did solve the problem as it was so intermittent. In fact I began to think it had gone away, then a couple of weeks ago the car developed a major fault. Did you see my L_O_N_G post about poor starting from cold accompanied by clouds of smoke? This has overshadowed the "holding back" problem as you can imagine. Most of the time this car is used around time for journeys of only a few miles. The problem never seems to arise then. It seems to appear only on longer, faster journeys when the engine is completely warm. On some such journeys the dreaded "check injection" message has appeared momentarily on the display (sometimes under hard acceleration), only to disappear after a few seconds. In view of my recent experiences I suspect that the annoying "holding back" could be a sign of bigger problems to come. I note that your mileage is similar to ours.
Earlier in this posting I mentioned possible wear in the "fly by wire" throttle position sensor giving incorrect signals. As you probably know, the TPS is a sort of rheostat (variable resistor or potentiometer - remember your school physics lessons?).
The strange thing is that on Friday last, I did a diagnostic scan on our car and one of the two fault codes was "problem with throttle track no 1 or 4". The diagnostic tool was able to carry out a test of the TPS. By slowly opening the throttle from idle to max, resistance figures were displayed. Mysteriously these appeared to be accurate but suggest an intermittent problem.

The best comparison of this fault is as follows; are you old enough to remember when cars had carbs and chokes? In winter, choke out to start the car, then ease in to prevent overchoking. Accelerate out of the first corner and the engine splutters and the car almost stands on its nose - a quick grab for the choke knob! My elderly Triumph is a prime example of this and is a pig to drive at this time of the year, until the engine is warm, which takes at least 5 miles!

Did the trip abroad go OK?
Mike

[MilosB]

Do you have any "tuning" box on it ?

[triumph2.5man]

No, it is just as it left the factory 100,000 miles ago!

[ikhan]

The best comparison of this fault is as follows; are you old enough to remember when cars had carbs and chokes? In winter, choke out to start the car, then ease in to prevent overchoking. Accelerate out of the first corner and the engine splutters and the car almost stands on its nose - a quick grab for the choke knob!

I had a similarish experience on another car, so not sure if this will help in anyway or not.

My petrol Alfa Romeo 156 had a similar problem, initially from a cold start only. 20 seconds after start up and driving along, the throttle would be totally unresponsive. The only way to get the car going would be to dip the clutch, rev it (as it would only rev with the clutch dipped), and then the car would work as normal. Eventually, this became a random problem, and even more severe on a hot engine.

This was diagnosed as a lambda problem, which was replaced and cured the problem.

Maybe it is a fueling issue (or the various sensors that control this) that you're experiencing?

[LewisR]

Sorry to bump the thread. But my car can also be added to the list that is doing this. However my turbo is on its way out so I have put it down to that.

[triumph2.5man]

That's very interesting. Is a pattern developing here?
I have neglected this thread a bit because the injection problems I mentioned recently have overshadowed all else. They got so bad I have had to take the car of the road as attempting to start it was upsetting the Environment Agency! (I jest but you get the gist). So I am unable to say if the problem continues. When I get it running again (!) (how long is a piece of string?) I will update this thread. I am hoping when I have solved this later problem, the "holding back" will disappear. Not much confidence though...
Any other sufferers? Keep 'em coming lads and lasses!
Mike

[VroomVroomClonk]

Hello again.
Yes, the trip abroad was fine thanks. Several hundred miles, mainly on motorways, without the engine missing a beat.
The car is normally used for commuting about 100 miles a day on a mix of B roads, A roads and dual carriageway, and it is virtually never in towns or traffic. So, like Triumph2.5man, my problem only ever occurs on long runs, but as I never do short runs or town driving it is not really a very fair statement for me to make.
My car is completely standard as far as I'm aware, it definitely doesn't have an engine tuning box connected to the common rail. Are there any other types I need to check for?
I am indeed old enough to remember carbs and chokes, and I still have some! As well as having the Megane, I am also a Triumph3.0man. Your description of attempting overenthusiastic acceleration with not enough choke and with a cold engine is very close to what I experience in the Megane, but I would say the Megane is slightly less severe than the cold Triumph version. Is yours a PI, TC or S, Mk1 or Mk2?
I note that my last update on this was just over a month ago, and since then it has been fine again. If I knew what the problem was, or was certain that it wouldn't get any worse, then it is so rare that I'd just live with it. However, with Triumph2.5man's other fuel related problems that have developed recently, I'm not feeling confident
I have always visualised a TPS as a wirewound rheostat, which is probably oversimplifying what it really is! But, a bit of dirt or fluff between the sliding contact and the coils, or a bit of a buildup of dirt on the contact could easily cause the sort of problem I am getting. CLIP says there are no faults with it, ... but could it be wrong???
And finally, as far as I'm aware my turbo is fine at the moment. It boosts well with no nasty noises, no nasty smoke and no oil leaks.