XM auto - EGR electric vacuum pump

lolingram · Post by **lolingram** » 04 Aug 2009, 09:39

Just acquired a 1996/7 XM 2.1 TD auto with BOSCH injection... (what luck!)

The EGR electric vacuum pump is making a horrid row, so I think the logical thing is to simply disconnect it and do away with EGR in one fell swoop. Can anyone (CitroJim perhaps) advise please? If so, where is the bloody thing?

BTW, Derv consumption on the run dow to SE France from Blighty: 41MPG with fully laden 1.5 tonne car at an indicated GPS 80-90MPH... sounds bloody marvellous to me!

jgra1 · Post by **jgra1** » 04 Aug 2009, 09:44

good MPG's Lolingram

John

lolingram · Post by **lolingram** » 04 Aug 2009, 09:54

good MPG's Lolingram

John

Like your bike choice John... if it had to be Jap, mine also.

citroenxm · Post by **citroenxm** » 04 Aug 2009, 10:17

Hi...

Just disconnect the plug its a double wire - white plug IIRC, near the injection pump and ECU's, I cant remember now - thats just a guess off the top of my head... but its defenatly in that area...

Paul

steelcityuk · Post by **steelcityuk** » 05 Aug 2009, 12:45

Not sure but try the RH wheelarch at the front, probably where the carcoal cannister would be if it was a petrol, that's where it lives on a 2.5.

Steve.

citroenxm · Post by **citroenxm** » 05 Aug 2009, 12:47

Its a Diesel, and it sits under the DRIVERS (off side) UK Cars, side wing, ahead of the wheel arch inner liner... the wires connecting it come through near the ECU's and its connected to the main harness in that area...

Paul

lolingram · Post by **lolingram** » 06 Aug 2009, 20:34

Its a Diesel, and it sits under the DRIVERS (off side) UK Cars, side wing, ahead of the wheel arch inner liner... the wires connecting it come through near the ECU's and its connected to the main harness in that area...

Paul

Here is how to disable EGR pump (and therefore EGR operation) on Bosch Inj XM 2.1TD.... works a treat! See:

http://www.topcorp1.com/swing/coffinclimax.html#EGR

citroenxm · Post by **citroenxm** » 06 Aug 2009, 21:40

AH HA! Exactly were I thought it was, JUST above the Suspension ECU's!!

Good post and link Lolingram... confirms my thoughts...

Rgds
Paul

steelcityuk · Post by **steelcityuk** » 07 Aug 2009, 09:08

A nice easy way to disconnect the EGR but if the valve's sticky or leaky it doesn't work. Also on ECU controlled engines that could put the car into limp mode. The blanking plate method is better but more time consuming.

Here's how I did it on the XM 2.5 I had.

Steve.

lolingram · Post by **lolingram** » 07 Aug 2009, 16:47

A nice easy way to disconnect the EGR but if the valve's sticky or leaky it doesn't work. Also on ECU controlled engines that could put the car into limp mode. The blanking plate method is better but more time consuming.

Here's how I did it on the XM 2.5 I had.

As you say Steve, a nice easy way to disable EGR on a 2.1TD XM. Mine is a 1997 auto with Bosch mechanical injection - in fact the only HiTech bit seems to be the EGR!

I would however point out that IF the EGR valve is sticky or leaky, (even if left in working order), it will require fixing..... the car now runs as sweet as a nut BTW, and slightly better on DERV to boot! 8)

Many thanks to you guys who helped.

steelcityuk · Post by **steelcityuk** » 07 Aug 2009, 19:09

That's exactly why I blank them off with a plate, it doesn't matter then if the valve's faulty. Though I have heard of the blanking plates being corroded through.

For owners of newer/fussier cars I would think twice before diabling the EGR system, for example it's thought that EGR faults are what leads to the demise of the Renault 1.9 DCi's.

Bosch pump, lucky man!

Steve.

lolingram · Post by **lolingram** » 07 Aug 2009, 20:14

For owners of newer/fussier cars I would think twice before diabling the EGR system, for example it's thought that EGR faults are what leads to the demise of the Renault 1.9 DCi's.

Do tell please...

steelcityuk · Post by **steelcityuk** » 08 Aug 2009, 10:20

Er well I thought it was well know about the failures of the 1.9 DCi.

This is the gist of what I've read/heard.

The EGR recycles an amount of exhaust gas back into the intake system of the engine under certain load conditions, this causes the temperature of the burning gasses to drop (I'd say that this is due to less Oxygen content and charge pollution). This reduces the amount of Nitrogen Oxides in the exhaust (this is a know to be true) and it also means that the EGT (exhaust Gas Temperature) is lower. Now supposing the EGR sticks shut or the vacuum pipe fails, the turbo will always be subjected to higher EGT than it was designed for, this in turn leads to seal failure which then means that oil escapes the turbos bearings which either leads to seizure or a run away situation where the engine is running on it's own oil.

>>

There's no doubt that EGR reduces EGT that's exactly why it's used. How much difference would it make, well I've heard 100 DC or more, that could cook the oil which would wreck the turbo bearings. But if it did this how would that lead to runaway? Surely not via the turbo directly feeding oil into the inlet, the inlet is pressurized and would force oil back into the turbo, so maybe the induction pressure gets past the seals into the turbos body and pressurises the sump (via the turbo oil drain) which then forces oil into the inlet via the PCV system. The engine would go into run away and either break something mechanically or seize through lack of oil.

One thing I've noticed on the XMs is that the diesel turbo is only oil cooled but on the petrol it's water cooled.

On a slightly different note last model Mazda 6 diesel owners having been having fun with their engines going pop due to their sumps filling with diesel (due to DPF regenration that pumps extra diesel) which then leads to run away.

Steve.

lolingram · Post by **lolingram** » 08 Aug 2009, 10:37

The EGR recycles an amount of exhaust gas back into the intake system of the engine under certain load conditions, this causes the temperature of the burning gasses to drop (I'd say that this is due to less Oxygen content and charge pollution). This reduces the amount of Nitrogen Oxides in the exhaust (this is a know to be true) and it also means that the EGT (exhaust Gas Temperature) is lower. Now supposing the EGR sticks shut or the vacuum pipe fails, the turbo will always be subjected to higher EGT than it was designed for, this in turn leads to seal failure which then means that oi

I would comment thus:

EGR is only used at fairly moderate throttle settings as I undertand things... the EG heating in calories max will always be at max exhaust volume, surely? i.e. balls out. It then follows, that Turbo heating will be at balls out.

So far as cooling of the Turbocharger, petrol burners give the Turbo a much harder life cycle, as is evedenced by the typical longevity of diesl Turbochargers in general, hence the need for heat exchangers.

In a previous existence, I owned a BMW 2002 Turbo, which was pretty unkind to its Turbocharger, much to the chagrin of BMW, who provided 2 under guarantee. After the guarantee expired, I ducted a large amount of air from the front air dam to around the Turbocharger, and there was no further problem.

citroenxm · Post by **citroenxm** » 08 Aug 2009, 21:56

steelcityuk wrote:

One thing I've noticed on the XMs is that the diesel turbo is only oil cooled but on the petrol it's water cooled.

On a slightly different note last model Mazda 6 diesel owners having been having fun with their engines going pop due to their sumps filling with diesel (due to DPF regenration that pumps extra diesel) which then leads to run away.

Steve.

Two things here... firstly, the XM isn't the only Diesel that doesn't need water to cool it, the oil main obvious purpose is lubrication, but because of the lower temperture operations of DERV engines the turbos dont get as hot - The XANTIA Td ALSO does NOT have water cooling on the Turbo..

On the Mazda note, thats an interesting thing, because FORD own about 60 per cent of Mazda, and Im not certain, but think the Mazdas use ford Diesel engines, and of course, by this Mazda generation, Ford was useing some of Peugeot engines, but Ford being Ford, mix n match some their own, some peugeots, which is the same for Mazda... incidentally, Mazda use their OWN petrol engines...

Bit of useless info there

Paul