Engine Tuning

[HAVIN_FUN_IN_MY_4B]

Forgive my ignorance but can anybody enlighten me about what sort of tuning can be done to a 3.5l petrol engine to improve fuel economy ? Have been reading a variety of posts tonight, particularly some on the petrol versus diesel debate and the figures getting bandied around for the petrol engines seem to be quite a deal better than what I currently get ? I seem to notice that the newer (after say 2005) engine seems to get quite a bit better economy than the older ones as well. I have a 98 NL and maybe it's just getting a bit tired ! I had some work done recently that involved a new o2 sensor, and at the time the other sensors checked out OK - am I right in figuring that the fuel / air ratio is controlled by the ECU only, via a range of sensors ?

Though I might start the process of checking for a problem with a compression test sometime soon - to check for ring / bore or valve issues that could be resulting in some unburnt fuel.

Thanks !

[Pagey]

What sort of economy are you getting?

[psproule]

Checking the current health of the motor is a good start. Has it ever had the injectors cleaned / changed? Yes, the ECU controls air/fuel ratios (AFR).

Next would be a set of extractors / headders and a free flowing exhaust. This will provide both an increase in performance, or if driven sensibly an increase in economy. Then start looking at reducing any induction restrictions. Beyond that we are looking at lifting heads off for flow work and / or remapping of the ECU. Or you could put it on BBQ Gas.

Is yours the DOHC? Get the plenum butterflys checked out before one falls off and it ingests it.

[HAVIN_FUN_IN_MY_4B]

What sort of economy are you getting?

About 450km to a tank mix of town and highway, and about 370-400 towing my 1500kg caravan. Given I can put about 85 litres in it from empty, that gives me a best of about 19l/100km or 20-21l towing the van

[damn_oatesy]

Just do the routine, clear the injectors check the timing (tune if nessesary) Adjust the mixture (on older models) and don't floor it constantly, most people eat through fuel trying to get up that hill a little faster. And if your still not happy, buy a Suzuki!