Fuelling

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mbunting
Posts: 712
Joined: 21 Dec 2001, 15:19
Location: United Kingdom
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Fuelling

Post by mbunting »

Many of us have read about increasing the power of the XUD engines, by tweaking max fuelling and wastegate operation.
Now, suppose I want to do the opposite - ie. reduce the amount of fuel going into the cylinders ( and hence possible wasted fuel ).
I would like to keep the turbo in, so no blocking up the sensor pipe. I'm basically looking to run the car lean. I'm currently getting between 38 and 42mpg from my 130k Xantia TD, oil and both filters changed regularly etc..
What made me think about this was the other night when pulling away, I could see large clouds of smoke in the chaps headlights ( I know you get this with 'old techs' anyway ). I've been spoilt with a CDi engine in the past, you see..
So, any ideas on how to reduce the fuelling ?
As an aside, I understand the 2.1td uses an electronic throttle ( ie. the interim test step between XUD and Hdi ). How difficult would it be to remove the ECU, sensor and pump from ( for example ) a scrapper, and transplant it into a 1.9 ?
I know of a 1.9Td which has been sat idle for the last three months. I've thought of examining it and making an offer ( to use as a testbed ).
Regards.
Mat
nick
Posts: 1079
Joined: 14 Mar 2001, 01:49
Location: Market Rasen, Lincolnshire
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Post by nick »

What year is your car ?
If its an earlier type 1.9TD it may be easier to transplant the injector pump etc, from a later 1.9 TD (1996 onwards, fitted with egr, ecu & an exhaust cat) than from a 2.1 engine. In my experience the later type 1.9 TD gave very slightly better fuel consumption (maybe only 2mpg more or so), and dont smoke anything like as much on hard acceleration.
The downside is slightly less power though.
However, unless you cover a massive mileage I can't think you're really going to save money by doing this.
Im reminded of my stepfather, who went to considerable trouble and expense to change the four speed box on his old 1.3 Ford Escort for a five speed, and then found that the fuel consumption was actually slightly worse as a result. He was not pleased :-)
Nick
Dave Burns
Posts: 1915
Joined: 14 May 2001, 05:30
Location: United Kingdom
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x 2

Post by Dave Burns »

There are several adjustment's that can be made to the Bosch VE pump, the two main ones are the full load delivery which set's the maximum amount of fuel that can be injected, and the full load delivery rate which decides how quickly full load delivery is reached as a function of manifold boost pressure.
The full load delivery screw is above the stop solenoid and below the boost diaphragm housing breather, to reduce fueling turn the screw anti-clockwise, there is a locknut and a tack welded ring to prevent the screw being turned in the clockwise direction hence increasing fueling.
The screw on top of and in the centre of the diaphragm housing, known as the smoke screw can be screwed outward's which will reduce the point at wich boost delivery begins.
Adjusting the actual boost delivery rate require's the removal of the boost diaphragm cover.
Before you think to much about pump adjustment's it would be wise to check the timing, you would need a small dial test indicator and a piston travel adapter for this.
Dave
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