my 2003 Td5 Auto has an issue that when you put your foot down at speed (say when overtaking at 80km/h) the engine begins to surge at around 4000rpm, the car jolts around and there is no chance to overtake unless you use less right foot and baby it at lower revs. This does not happen all the time and when it is on song the engine will happily rev to 4500rpm.
I have replaced about 5 airflow meters (I get dust also on teh airflow meter even using a K&N oiled filter) in 4 years and that seems to work for a bit but it always returns. As usual it apparently cant be replicated when in the workshop??? What led to the airflow meter as a potential problem was that Iit should read around 54 on test book and one was reading only 4. Others have read normal but when i disconnect the wiring to the airflow meter it does not surge, revs past 4500rpm even if it sound s abit rough and a bit down on power low down.
The ECU is unchipped, I have a safari snorkle, 32" All Terain tyres, ARB bar and winch, LR tank etc.
Can anyone offer advice?
Secondly and possible related is the bad fuel economy. When I purchased the car at 48,000Km unmodified it would get 10km/L around town and highway. these days it gets 7km/L (14L/100) if i am lucky around town no matter how carefully I drive and on the highway it might get 7.5km/L (13L/100) on the highway and I have gotten 6.2km/L around town (16L/100). Even with teh barwork and tyres etc I would expect to be getting 8km/L (12.5L/100). The best I have gotten a few years ago fully loaded with roof tent, jerries etc was 8.6km/L but even unloaded on teh freeway I cant get better than 7.8km/L (12.8L/100). It has just ticked over 150,000km.
Is this normal? what do others get? what could be the problem?
