Thread: How to improve 4.6 economy

Bosch gen3 injectors seem to make a difference, people were talking about figures as low as 11 with them.

Bare in mind though, unless your injectors are new or very clean and fuel pressure good the dash readout won't be very accurate.

Running on lpg will stuff around with that figure too as you may need more throttle on lpg.

Id say though, if you were getting 17 on petrol on the hwy there's something not quite right.

How'd the trip go? Would be nice and green through the Darling I imagine.

Benji,

Absolutely stunning, green everywhere not like when I was around there 10 years ago, the view from the 'Jump ups' was awesome, and how stupid are Emus!!, thank god Hoovers' got good brakes.

I think the trip computer is close, as I was emptying my wallet quite regular. It got down as low as 15.4 l/100km sitting on 90kph. I'd kill for 11's. So what are Gen3 injectors precisely, also do these injectors impact across all driving conditions?

Rob

they have allways been known for being a motor that likes a drink and the gas fittment will upset the original setup. what model p38 do you have? there are a few things to check thermostat (should run in low to mid 90'sC) airflow meter, O2 sensors (if fitted) etc. gems i can lean off during tune up, but bosch has to have a new map. changing camshafts, upping compression and moving the injectors can help but is a lot of work. the first thing to do is get the original setup checked by someone you trust.

I'll stick my neck out and offer the opinion that the numbers are not too bad! weight and aerodynamic drag are the biggest killers of fuel economy. As Rupert has also pointed out, having the option of running on gas means that the vehicle is not optimised for petrol...

Once you exceed about 80kmh the drag increases according to the inverse square law... double speed means x4 times drag... so you have x9 drag at 90kmh vs 30kmh etc. Carrying a roof top tent, spare fuel containers etc means that your drag coefficient is high to begin with. Add to that approx. 3/4 tonne payload, roughroads etc and you're heading into small tray truck equivalents. The V8s were/are virtually all of the low compression variety and so while they are under stressed, they are also much less efficient..

I've been wrestling with this also (1999 Bosch 4.6) . A rough cost benefit to get an improvement of say 4L/100 km equates to $6 (say $1.50 /litre) or 6c/km. A $7000 "fix" to achieve this equates to about 116, 000 km to break even at today's prices ....

I've concluded it's all too hard and so am concentrating on maintaining the vehicle in good condition and storing as much as possible inside, taking as little as possible and driving 'sedately'... last trip to Sydney with 4 adults and luggage ...about 10.5 hrs actual driving time each way... a shade over 12.2 L/100km.
FWIW... a cousin recently traded his Audi Q7 3L Tdi on a new LC 200 diesel (after a confrontation over a $12, 000 repair demand for a new fuel pump ...only a couple of months after warranty expired..).. anyway, his Toyo gets about 11.8 on the hwy unloaded and 17-18 loaded with camping gear ...roof rack etc

Originally Posted by Rupert Prior

they have allways been known for being a motor that likes a drink and the gas fittment will upset the original setup. what model p38 do you have? there are a few things to check thermostat (should run in low to mid 90'sC) airflow meter, O2 sensors (if fitted) etc. gems i can lean off during tune up, but bosch has to have a new map. changing camshafts, upping compression and moving the injectors can help but is a lot of work. the first thing to do is get the original setup checked by someone you trust.

Rupert,

I just put Hawkeye on Hoover and " fault code 18 O2 probe missing or intermittent bank 2 ".

I had this fault about 6 months ago, and G. Coopers changed the sensors. MMM maybe not the sensors as the fault will clear but returns on engine start.

P.S 2001 Thor, new cooling system .

Originally Posted by Hoges

I'll stick my neck out and offer the opinion that the numbers are not too bad! weight and aerodynamic drag are the biggest killers of fuel economy. As Rupert has also pointed out, having the option of running on gas means that the vehicle is not optimised for petrol...

Once you exceed about 80kmh the drag increases according to the inverse square law... double speed means x4 times drag... so you have x9 drag at 90kmh vs 30kmh etc. Carrying a roof top tent, spare fuel containers etc means that your drag coefficient is high to begin with. Add to that approx. 3/4 tonne payload, roughroads etc and you're heading into small tray truck equivalents. The V8s were/are virtually all of the low compression variety and so while they are under stressed, they are also much less efficient..

I've been wrestling with this also (1999 Bosch 4.6) . A rough cost benefit to get an improvement of say 4L/100 km equates to $6 (say $1.50 /litre) or 6c/km. A $7000 "fix" to achieve this equates to about 116, 000 km to break even at today's prices ....

I've concluded it's all too hard and so am concentrating on maintaining the vehicle in good condition and storing as much as possible inside, taking as little as possible and driving 'sedately'... last trip to Sydney with 4 adults and luggage ...about 10.5 hrs actual driving time each way... a shade over 12.2 L/100km.
FWIW... a cousin recently traded his Audi Q7 3L Tdi on a new LC 200 diesel (after a confrontation over a $12, 000 repair demand for a new fuel pump ...only a couple of months after warranty expired..).. anyway, his Toyo gets about 11.8 on the hwy unloaded and 17-18 loaded with camping gear ...roof rack etc

Hoges,

Thats quite thought provoking.
To have so much on the roof is not ideal, I agree. The main concern, I guess, knowing that I will never recover my costs incurred with this car I'm prepared to invest a bit more, keep it longer and enjoy. My hope is I will gain extra range without having to tow a tanker behind.

Anyway I'll have to address the O2 issue first.

Rob

Originally Posted by Robsrod 58

Hoges,

Thats quite thought provoking.
To have so much on the roof is not ideal, I agree. The main concern, I guess, knowing that I will never recover my costs incurred with this car I'm prepared to invest a bit more, keep it longer and enjoy. My hope is I will gain extra range without having to tow a tanker behind.

Anyway I'll have to address the O2 issue first.

Rob

Towing a tanker is exactly what I did a couple of yrs ago... 250L transport tank from a new MB prime mover lives on the draw bar of my DIY camper trailer only filled once we are about to leave the bitumen....

Not 100% sure on this but think I am right. The Gen 3 Bosch injectors are a direct replacement for the Lucus injectors on Gems cars. I have swapped them on a Classic with good results. The Thor engine I presume would already have the Bosch injectors.
Anyone looking to do the swap get onto ebay and search for Ford 19lb injectors. They are all yellow in colour. I sorted a set last week for a friend and they cost US$60 + Shipping for a full set of 8 used but ultrasonic cleaned, flow tested with new o rings and pintile caps. They look different from the Lucas but are a direct plug and play replacement