Lumpy C5 - now resolved.

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Lumpy C5 - now resolved.

Post by myglaren »

I think I have mentioned elsewhere on the forum that my C5 has been running 'lumpily' for the past few months - can't recall exactly how long unfortunately, probably since around Christmas time and gradually getting worse.

I took it to be an injector on the blink and dropped it in with my friendly local mechanic for a bit of a look-see.

He checked the injectors and a pile of other stuff and all was as it should have been. In consultation with some of the mechanics at the local dealership (TCC) he diagnosed the dreaded dual mass flywheel was breaking up.
I agreed with this as there has been a chirping sound coming from that locality for ages. At first we thought it was the crankshaft pulley but when I had the camshaft drivebelt, tensioners and water pump changed at the last service he also replaced the pulley, auxiliary belt and tensioner which of course didn't fix it.

I fear I may have some culpability in it's demise as when coming home from work each day I usually descend a fairly long steep hill and am often doing around 90 approaching the roundabout at the bottom. I rarely use the brakes and drop it into third and let the clutch out with a bang, while thinking "I really should stop that, can't be any good for the DMF"

Anyway, he pulled it out and changed it and stuck a new clutch in for good measure while the gearbox was off.

There is a huge improvement, the gears, formerly quite slick, are like oiled silk now. The clutch is so light it almost feels wrong, as Jim and others have described a new Xantia clutch being.

I saw the removed components, the DMF had so much slogger in it it's a wonder it held together at all, the clutch was worn down to next to nothing, so it was about to need doing anyway (130,00 on the original clutch).

The exercise cost a fair few quid, as you might expect. Unfortunately it didn't cure the original "missfire" which is quite pronounced now.
It is only manifest on idle, the car runs well although without as much poke as I feel it should have. Fuel economy is rather disappointing too but this may be more attributable to me booting the car around a lot and far too many short trips. On a long journey it isn't too bad but could be better IMO.

The problem has now been attributed to suspected problems with a valve or valves. The next step being for me to take the car back after easter and rip the head off to see what is going on there.

George did show me a HDi head from a dead C5 that one of his customers was running on veg. Not for very long, it has to be said, there was a hole burned through the edge of #2 exhaust valve and George said, a corresponding large hole burned through the piston crown.
He kept the head for amusement but the block had been turned into bean tins.

Anyway, after all that, I'd appreciate any opinions and experiences of similar problems that others here may have had.
Last edited by myglaren on 05 Sep 2009, 15:08, edited 1 time in total.
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Post by citronut »

Steve
is it possible the atipolution devices/filter could cause this sort of fault,

have you had it hitched up to a DIS_LEXIA yet

regards malcolm
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Post by myglaren »

citronut wrote:Steve
is it possible the atipolution devices/filter could cause this sort of fault,
Ain't got one on my old heap Malcolm :)
have you had it hitched up to a DIS_LEXIA yet
No. Might have to run down to Jim's tomorrow (not really, you can breath again now Jim):twisted:
regards malcolm


Thanks for the thoughts though Malcolm.
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Re: Lumpy C5

Post by Citroenmad »


I fear I may have some culpability in it's demise as when coming home from work each day I usually descend a fairly long steep hill and am often doing around 90 approaching the roundabout at the bottom. I rarely use the brakes and drop it into third and let the clutch out with a bang, while thinking "I really should stop that, can't be any good for the DMF"
Going from 90mph in 5th to 3rd gear is most likely your problem :lol: I asume thats a typo! Brakes are cheaper than gearboxes and clutchs, my brakes get a lot of use :lol:

Have you tried a new MAF sensor? The C5 estate we have is a much much slower car than my C5 hatch, even though they have the same engines. So i swapped the MAF from the hatch to the estate as a test and it was like a totally different car, with bags more pull than before.

You really have to work the engine and gears hard to make progress, especially uphill with a load. Although in my hatch it storms uphills with no problem and it needs far less gearchages to drive it normally. Anything under 2K rpm in the estate and its a no go, just wont move, which make for an interesting time getting out of junctions quickly, lots of revs are needed.

However, the estate does have a new MAF sensor, although its a very cheap looking unit, with no writing and looks very different inside to the genuine Citroen one on my hatch. So the estate needs a new CITROEN MAF sensor, which should make it perform like the hatch, as it certianly did the the hatchs MAF fitted.

The estate also has a slight lumpy running when on idel, but very very rarey, but with th other sensor fitted i didnt experience this. For the sake of £110 from Citroen, it might be worth a go.

Now i know some say if you have a MAF fault it will come up as a code, but thats not always the case, it can depend on how bad it is. My money would be on that.

130K from the original DMF is very good i would say. Our estate had a new clutch fitted by the garage just before we bought it from them, as it was close to slipping, however the DMF is still fine, at 105K miles. My hatch needed a complete new clutch at 60K, it now has no DMF at all, but a solid flywheel, much better!

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Post by myglaren »

I did see your write-up on your MAF experiences in your other thread and it has me considering a replacement, once the head has been off and we see what may be lurking under there.

No, it wasn't a typo! I fully agree that it is not wise to dump a strain like that on the power train, must pack that in. I have been doing it far too long with other cars and no ill experiences so it is a hard habit to break.
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Post by CitroJim »

myglaren wrote: No. Might have to run down to Jim's tomorrow (not really, you can breath again now Jim):twisted:
You'd be more than welcome Steve :D

In fact, time it right and you can help me haul the engine back into the V6 :wink:

I was interested to hear of the veg damage :twisted: Did he offer any explanation as to why the valve burned?
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Post by myglaren »

Only joking Jim, not venturing out this weekend I don't think, far too much traffic on the roads for comfort. I like to make progress not sit around in traffic jams.

Wouldn't fancy a run of that distance if there is a valve off, might kill it completely.

He didn't offer any theories as to why the valve and piston had burned. Only the fact that it had been run on veg.
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Post by Citroenmad »

Our estate had a new MAF before we bought it, just before infact. Im not sure why or what its symptoms were, but it must have cured it. However now its really slow, i was wondering before i swapped MAFs what on earth a 90bhp C5 estate would be like to drive if this is how the 110 performas - mainly thinking it must have a lot of extra weight.

Not so! So ill replace that on it and it should be a much nicer car, and MPG should improve too, as it wont need working so hard.

Wow, does it even do 90mph in 3rd!? :lol: That must be close to 5Krpm? I cant imagine it would like that much, many new cars would go into limp home mode after something as sudden as that. I much prefer my brakes from such speed, they work wonders :roll:

Have you tried cleaning the MAF, i did that with my hatch, seemed to make a difference to performance and MPG just by cleaning it. I used contact cleaner and air intake cleaner for the intake pipes. That worked nicely too.

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Post by myglaren »

Have you tried cleaning the MAF, i did that with my hatch, seemed to make a difference to performance and MPG just by cleaning it. I used contact cleaner and air intake cleaner for the intake pipes. That worked nicely too.
Might have a bash at that tomorrow as it will be around a week before it goes back for the head to be seen to.
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Post by steelcityuk »

If you can get it hooked up to a Lexia, take a look at the fuel correction figures - the total permissible correction is 5%. If one or more is out then that points to an injector issue. Could it even be that the flywheel sensor is flakey causing an injection timing issue?

I'm told there's countless fake MAF sensors out there and the only way to be sure of a genuine one is to buy from a dealer.

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Post by myglaren »

Surely I would get an engine management light and a warning on the display if that were the case?
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Post by steelcityuk »

I don't think that you would, such a problem wouldn't require the engine putting into LOS mode. My (limited) understanding is that the ECU 'watches' the pulses of the flywheel sensor to check that they are as expected (regular), if not the ECU alters the fuel correction values to achieve this. This is why HDi's should never be lumpy. So my assumption is that either 1 or more injectors have a fault (would a leakback test help?) or the sensor's playing up.

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Post by myglaren »

steelcityuk wrote:I don't think that you would, such a problem wouldn't require the engine putting into LOS mode. My (limited) understanding is that the ECU 'watches' the pulses of the flywheel sensor to check that they are as expected (regular), if not the ECU alters the fuel correction values to achieve this. This is why HDi's should never be lumpy. So my assumption is that either 1 or more injectors have a fault (would a leakback test help?) or the sensor's playing up.

Steve.
Leackback test was done as it was first assumed that an injector was duff.
There remains the possibility that the flywheel sensor is kaput.
I'll get this checked before they remove the head.
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Post by steelcityuk »

A trip to a Bosch specialist could work out well if you have one locally. They seem to really know their stuff when it comes to diesel engines and they have all the proper kit.

Hope you get it fixed soon.

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Post by wheeler »

myglaren wrote:There remains the possibility that the flywheel sensor is kaput.
I'll get this checked before they remove the head.
Unless the engine speed sensor has metal swarf stuck to the magnet in the sensor & corrupting the signal I would have thought that the sensor either works or doesent work, without engine speed info the engine wont start or run at all.
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