Technical 2005 1.9JTD big MPG missmatch

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Technical 2005 1.9JTD big MPG missmatch

queeg

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Oct 5, 2014
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I've not had much to do with Italian cars for quite some time and I'm now the proud owner of a 55 plate 8v 1.9JTD Doblo Dynamic.

Long story short, it was my mum's and ended up sitting for 4.5 years after she got sick and eventually passed away. It has had a pretty good going over, belts and waterpump, filters, fluids, brakes, exhaust, aircon radiator and a few little things like bulbs. The only fluids not done are the PAS and gearbox. I even took the fuel sender out of the tank to check for water and bug, thankfully clean. The engine gets up to temp and sits there.

Trip average MPG on the dash is saying low 50s average but distance driven vs fuel put in is averaging low 40s. Mix of city and motorway. My old V6 Alfa 166 MPG was pretty accurate albeit horrifically low. My mum never kept records so I have no idea if it has always been that far out. I know the dash MPG displays are not accurate but this is quite an inaccuracy.

It had suffered from a lumpy idle and was a bit of a smoke monster on hard acceleration when my mum was driving it. No codes stored. I did the old unplug each injector one at a time to see what happens test and number 2 made no difference to the idle. I swapped it out for a second hand injector from ebay and that solved the lumpy idle but it was literally a week before she stopped driving. Now when driving there is very little smoke.

I've not looked at the MAF or MAP sensor. The smoke issue it used to have could have made a mess of the EGR. Given the lack of space in the engine bay I'm trying to avoid taking too many things to bits. It drives OK for something with the aero of a shoebox and doesn't seem down on power but then I don't have much of a baseline. I've done a few long motorway trips in it with no drama.

It also has a glowplug issue with the flashing light on the dash. Got a P0380 in the ECU but nothing else. #4 glowplug is dead but will not come out. 1 to 3 are brand new bosch. I need to do some more electrical tests on the relay as it appears to be OK but the engine starts just as well when cold with it unplugged.
 
I had a 55 Doblo 1.9 JTD MPV I drove it hard and generally low 40s mpg measured by comparing mileage to actual fuel, slightly worse in winter.
When I first got it black smoke a lot but traced it to a poor wiring at MAF sensor plug.
It does sound like garage couldn't change the no4 non Bosch heater plug, if there is danger of it snapping and car is starting OK it may well be safer to leave it. Apart from applying oil around plug thread area and very gentle rattle/impact gun use which sometimes shakes it lose without breaking even better than gentle leverage with a socket and bar, that and hot and cold application to area, to be honest I would not open a possible can of worms if you can live with it.
 
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