xantia 2.1td problems with revs

dave.t · Post by **dave.t** » 29 May 2004, 16:28

engine keeps on revving up and down when idling and revs up when changing gear,fault is intermittant only pattern i can see is it seems not to do it when the engine is cold .i,ve had it coded but nothing showing.had it in to a diesel specialist whos changed the filter,diesel pump and the accelerator sender but fault still occurs.really dont want to scrap it but losing avenues to explore.please help. thanks in advance

AndersDK · Post by **AndersDK** » 29 May 2004, 21:39

Dave,
Diesels are not crammed with elaborate electronics (that can go wrong) to control the engine - like petrol engines.
A very common problem known from ages with diesels having their own mind on engine rpm - is the dreaded engine oil burning problem.
Especially when engine is hot, the heavier engine oil is easily considered - and combusted - as diesel fuel in the engine.
No doubt your engine emits some bluish smoke when is misbehaves ?
By nature, any engine oil reaching the combustion chambers is highly unwanted - and can not be controlled as fuel.
As your engine is turbo fitted, the oil will come either from a leaking oil seal on turbo cold (intake) side, or the engine itself.
Remove intercooler to see clear traces of oil from turbo cold side.
Even try run the engine with intercooler removed (it will of course be weaker) to see if it still rev up when hot.
The fume hose from crankcase is likewise a pointer : only slight pressure should come from normal blow-by. High pressure means severe blow-by from piston rings, and will press out engine oil to intake.

Stuart McB · Post by **Stuart McB** » 29 May 2004, 23:57

I agree with the last reply but I'd also go for a breather pipe clean aswell. Any of the oil return hoses back to the rocker or sump take off and clean. There may be some s**t stuck in one and this would also take it's toll on the engine. Also have you changed the air filter?

Dave Burns · Post by **Dave Burns** » 30 May 2004, 00:24

This engine and turbo IINM does have electronic control, have you changed the TDC sensor and is there also an injector lift sensor on this model.
I don't go for the oil theory because of the distance it has to go to get into the engine, plus going through the intercooler most of any escaping oil would get left behind, clinging to the inside of it all.

Dave

dave.t · Post by **dave.t** » 30 May 2004, 23:32

thanks for your replys the car does have fancy electronics (unlucky for me) something i forgot to mention is the fault doesn't happen if the revs are above 2000 so i don't think its sh*t in the hoses.thinking it could be a sensor but wouldnt find a tdc sensor if it smacked me in the face.i was hoping this was a common fault to these engines which some poor sod had had and managed to fix.so i could tell the so called specialists how to put it right without them changing parts that it doesn't need and trying to charge me for them.

NiSk · Post by **NiSk** » 31 May 2004, 13:51

. . . " when the engine is cold" . . .
I'd put a bet on air ingress through the fuel preheater - a well known TD12 problem. Run a fuel line straight from the metal pipe at the back of the engine to the fuel filter.
//NiSk

Dave Burns · Post by **Dave Burns** » 31 May 2004, 15:19

The tdc sensor on pug/cit diesels typically is located near the flywheel as it uses this to generate its pulse, normaly found in the bell housing flange on the back of the block, or in the gearbox bell housing, usualy the top of it.
This engine has a heated fuel filter on the thermostat housing like all other modern cit indirect diesels, air getting into this EDC pump is more likely to stop the engine than cause it to rev.
Dave

NiSk · Post by **NiSk** » 31 May 2004, 20:26

I believe the XM's with electronically controlled injection use the Lucas-CAV EPIC pump, which is basically an old CAV pump with a few bits of electronics hung on it. These pumps use the incompressibility of the diesel fuel to transfer internal control forces, so air in the fuel causes havoc.
Check out:
http://www.tramontana.co.hu/citroen/engine/diesel.html
Zeljko Nastasic (author of above) isn't terribly enthusiactic about CAV pump s- especially worn ones.
//NiSk

Dave Burns · Post by **Dave Burns** » 31 May 2004, 21:24

A totaly different animal, total electronic fly by wire control, so not an old CAV, no reliance at all on old methods of regulating delivered fuel quantity.
http://www.delphi.com/pdf/e/epic.pdf
Dave

dave.t · Post by **dave.t** » 01 Jun 2004, 00:07

it is a lucas epic phase 2 pump with fly by wire.the specialist diagnosed it as the problem fitted a factory unit but it still is exactly the same .now wants £750 for the pleasure lol.must say i can see a few air bubbles going into the pump (through the plastic tube)but even when it isn't hunting.thanks for your comments everyone much appreciated.

dave.t · Post by **dave.t** » 01 Jun 2004, 21:59

call me daft if u like.but all this morning the fault kept reappearing.i then had to fill up and the fault hasn't re occured for the last 25 miles in stop start traffic where the fault is more noticeable.can diesels suffer from this on low tans of diesel and if so why.thanks for posting

Kered · Post by **Kered** » 08 Jun 2004, 02:37

I have a friend with a 2.1TD who is experiencing similar problems so I have been following this thread with interest.
The hunting usually occurs from cold and sometimes the engine starts running away. The thought now is air. He definitely has an air leak as he can see the bubbles in the pipe. He has found that if he pumps the primer before starting in the morning then it behaves perfectly.
I don't know where the air ingress is yet but it could well tie in with dave.t when his runs fine on a full tank.
Opinion appears divided over the injector pump as to whether it uses the hydraulic properties of the fuel within the pump to control the governor etc. If it is a modernised version of the old Lucas that still uses the hydraulic properties of the fuel then maybe that really is the reason.
Derek

dave.t · Post by **dave.t** » 07 Jul 2004, 00:52

kered has your freind got to the bottom of the problem because i'm still suffering here[:(]being told to try the ecu now but can't find one for love nor money

zorgman · Post by **zorgman** » 07 Jul 2004, 01:06

got a ecu sitting right here next to me
lucas DCU R 040100200 C 12V 23/2/98
XUDLC01
loads of other numbers and theres a second box made by valeo attached to it
make me a offer i cant refuse it came off a good running car that wacked up the back end

Kered · Post by **Kered** » 07 Jul 2004, 19:50

Hi Dave.t
Sorry I have no more info as I've been on holiday and now he is. I'll report back if anything has been discovered.
Derek