Xantia XUD Turbo - lack of boost

lolingram · Post by **lolingram** » 27 Dec 2006, 17:14

I have recently acquired a Xantia 1997/Rreg XUD Turbo estate in good general condition - 75KMiles. Shortly afterwards a lack of urge at the top end of the rev range has become apparent...

The top end boost is lack-lustre, but the turbo can be heard whizzing away nevertheless - seems like not enough diesel being injected at the mid to top of the rev ranget. Filters and the usual stuff check out OK.

Engine is 1.9 XUD with mechanical Bosch injection, but has cat and EMU black box.

1) No smoke apparent in the mirror (at night especially) at 3000rpm+ - regime where lack of urge really begins to be seen.

2) I note that there is a sensor situated on the inj. pump that would appear to relate to throttle position

3) VIN: VF7**************[VIN obfuscated, can be read by forum staff]

Problem seemed to manifest itself after a quick engine wash down. Before it went like sh**t

I once owned a Pug 205TD (nice car) that had a Lucas pump (yuck!), that lost most of its boost due to the boost pressure interface in the pump going AWOL - diaphragm I seem to remember.

Can't think of anything else relevant. This is the wife's car, and driving around locally is pretty OK - pulls well from around 1800rpm to 3000, but no real grunt as previously was the case. As I said seems to lack extra fuel to go with the air boost.

Any further help much appreciated.

AndersDK · Post by **AndersDK** » 27 Dec 2006, 17:26

There is absolutely no grunt past 3500-4000rpm in an XUD turbo, and I hardly believe you can find any other turbo diesel with any grunt above that rev range.
Just to make sure you are aware of this.

Check the small pressure hose to the diesel pump regulator diagphram. It may well be gunked up/ split / or has fallen off.
The faint turbo whining on the other hand is somewhat indicative of an airduct leak somewhere - which is a wellknown problem.
Air duct hoses are prone to "shoot off" or split.

lolingram · Post by **lolingram** » 27 Dec 2006, 17:39

Thanks for your quick reply - I hear what you say about grunt above 3500... I would merely say that this doesn't go anyhting like it did before I gave the engine a clean. Could it be related to the ECU in this version - does this have anything to do with fuel delivery under max boost?

I will re-check the hoses to/from exchanger, although when these pop off, you can hear the escape of air with the windows open... I have remade the connection to the pump regulator diaphragm. Could the pump aneroid valve be at fault?

Thanks again

AndersDK · Post by **AndersDK** » 27 Dec 2006, 20:28

Try the Peugeot department of the forum - search on turbo boost - etc.

We have had a number of threads on this issue not too long ago.
Seem to remember that a temp sensor can play up and do this. But I'm unsure as to which modelyears it applies.

lolingram · Post by **lolingram** » 27 Dec 2006, 20:54

Wilco.

deian · Post by **deian** » 27 Dec 2006, 21:18

well since it happened after you cleaned the engine area, maybe water got into a plug somewhere, or you knocked a plug out (it can happen), maybe someone could clarify as to which plugs would make you loose turbo pressure, something to do with the dump valve somewhere, a bit of WD40 would work well me thinks

good luck

citronut · Post by **citronut** » 27 Dec 2006, 21:54

check all air duckting and vaccum pipes,make sure they are all conected and tight
regards malcolm

lolingram · Post by **lolingram** » 28 Dec 2006, 07:37

Can I run the engine with the ECU unplugged in order to eliminate this item from the list?

citronut · Post by **citronut** » 28 Dec 2006, 08:40

dont go getting all complicated to start with,if any of the intercooler pipes/duckting are not on and secure,the turbo will not work,also if your car has an engine management ECU it allmost certainly will not run with it unpluged,besides i think the imoberliser runs through the ECU,i had a guy come to me with a 1.9TD xantia he had just bought cheap as the seller said it needed a new turbo,i had a look under the bonet and found the duckt which goes to the intercooler just below and forward of the battery tray disconected,so i reffited it he took it for a test drive and on returning said it is a differant car
regards malcolm

lolingram · Post by **lolingram** » 11 Jan 2007, 17:06

I carefully eliminated the fuel filter, air filter, intercooler trunking for leaks and general wiring etc,. etc.

In the end, I disconnected the throttle arm position potentiometer, and checked the tracking of the pot with a multimeter:

1) There is an open circuit between the outer two wires - brown and black in other words infinity.

2) The resistance in ohms between green (centre) and brown starts at 1.3K with the throttle arm at rest.

3) When the throttle arm is opened the resitance progresses up to 1.9K ohms

So.... I ran the engine without the throttle position pot connected. It started just as normal and idled at 1000rpm - again normal.

I drove the card up the road and it now goes like s***t off a shovel, with no smoke - at least as well as before the problem - possibly a gnat's foreskin better.

So... what does the throttle arm pot tell the ECU? I am inclined to leave as is. The problem followed a wash down of the engine, and clearly, the throttle arm pot got some water into it which has screwed it up permanently.

Anyone got any answers/thoughts? Can I leave the pot disconnected?

dont go getting all complicated to start with,if any of the intercooler pipes/duckting are not on and secure,the turbo will not work,also if your car has an engine management ECU it allmost certainly will not run with it unpluged,besides i think the imoberliser runs through the ECU,i had a guy come to me with a 1.9TD xantia he had just bought cheap as the seller said it needed a new turbo,i had a look under the bonet and found the duckt which goes to the intercooler just below and forward of the battery tray disconected,so i reffited it he took it for a test drive and on returning said it is a differant car
regards malcolm

KevMayer · Post by **KevMayer** » 15 Jan 2007, 20:17

Does the engine sound rough on tickover ?

I can't remember, even though I discussed the same point a while ago, but If you search on here you'll probably find that when the pot is disconnected the injection timing goes to full advance. If it's not gone too far advance then it may well appear to run well.

If it's too advance you'll get like a pinking or knocking sound.

lolingram · Post by **lolingram** » 15 Jan 2007, 22:19

With the pot dis., everything runs very well indeed; tickover a steady 1000rpm, starts well from cold, and goes like stink.

I have in the distant past, re-timed 304D and C35 pumps, and have done these 'au pif' - in other words by ear, and eventually got things spot-on. In this case the pump is not overadvanced I am certain of that.

Does the engine sound rough on tickover ?

I can't remember, even though I discussed the same point a while ago, but If you search on here you'll probably find that when the pot is disconnected the injection timing goes to full advance

lolingram · Post by **lolingram** » 25 Jan 2007, 16:11

Just to stay that this problem has been fully resolved... it was the EGR screwing things up. Now fully disconnected and everything alles gutes!

Thanks to all those who contributed.

I have recently acquired a Xantia 1997/Rreg XUD Turbo estate in good general condition - 75KMiles. Shortly afterwards a lack of urge at the top end of the rev range has become apparent...

The top end boost is lack-lustre, but the turbo can be heard whizzing away nevertheless - seems like not enough diesel being injected at the mid to top of the rev ranget. Filters and the usual stuff check out OK.

Engine is 1.9 XUD with mechanical Bosch injection, but has cat and EMU black box.