14 replies to this topic

[Screwdriver]

My 96 JDM SPi (with aircon) is driven in central London where admittedly traffic isn't great. Over the past 18 months, the car has had several  potential fuel economy drags addressed such as:

 

1) New vacuum hoses and fuel trap

2) New K&N filter

3) New Timken front bearings (genuine)

4) New grounding wiring 

5) New belts

6) New water pump/ coolant

7) New brake assembly

8) New plugs

9) VR1 Engine oil

 

Fuel economy has ranged from a best of 7.5L/100km (37mpg) to 12L/ 100km (23 mpg), measured somewhat precisely over the past 18 months. The car runs very well and feels great to drive.

 

Have I missed addressing something to improve my economy to where other SPi have reported?

[genpop]

Hi,

if you drive only short distances this could be normal. But what about your water temperature, is the neeedle coming up to half of the gauge?If the temperature sensor is bad the engine runs in limp mode and takes a lot of fuel. You should look here in the forum who has test equipment near to your home and ask for assistance. Or if you are convienent with computers build your own equipment. Google for mems-diag or mems gauge.

[Screwdriver]

I typically drive 4-8 miles a trip, weekends only. The thermostat was also replaced recently and yes the needle comes up to half (triggering the cooling fan fairly regularly in city conditions). I'd have to say that the motor certainly doesn't feel like it runs in limp mode but perhaps it's not perceptible? 

 

For perspective, at its service last month, Croydon Minis (Mike and Russel both) said that it was the best Spi they had driven. Outside of the fuel filter, I can't think of anything else that may need precautionary replacing. 

 

 

 

Hi,

if you drive only short distances this could be normal. But what about your water temperature, is the neeedle coming up to half of the gauge?If the temperature sensor is bad the engine runs in limp mode and takes a lot of fuel. You should look here in the forum who has test equipment near to your home and ask for assistance. Or if you are convienent with computers build your own equipment. Google for mems-diag or mems gauge.

[Wiggy]

Doesn't sound to me like you've got anything to worry about. City driving kills economy. I think your numbers sound about right.

[Screwdriver]

My point really is that, even when driven on the motorway at 50 mph for atleast 70% of the journey, I've never exceeded 37 mpg. Doesn't seem normal to me based on other posts but I defer to the wisdom here. 

[Wiggy]

It's a tricky one. There's so many variables. You've covered a lot, but there's also tyres and pressures, maybe the head could do with a decoke, maybe other people haven't measured their economy as accurately as you.

[Screwdriver]

Very helpful comments/ questions. I'll try to add more:

 

1) Tire pressure set at 31 when warm every 6-8 weeks. These Dunlops run on 12" genuine magnesium Minilites.

2) I've used the Auto-RX treatment with the engine oil to clean motor internals and the Chevron Techron petrol additive annually. In 15 years of car ownership, I haven't found more transformative oil/ fuel additives (broad consensus and my own personal experience). 

Edited by Screwdriver, 01 December 2018 - 04:22 PM.

[Wiggy]

A petrol or oil additive won't decoke the head for you. There are products available (that I've never tried), but it's not hard to whip off a Mini head and give it a clean.

Rear brakes aren't dragging are they?

[Screwdriver]

A petrol or oil additive won't decoke the head for you. There are products available (that I've never tried), but it's not hard to whip off a Mini head and give it a clean.

Rear brakes aren't dragging are they?

 

Not perceptibly. They were recently adjusted and serviced. I should have shared that the head is shiny (the car only has 65K miles on it).

[hunterg30]

Depends on how heavy your right foot is

[humph]

Since 2010 my spi Sidewalk has averaged 37.15mpg. It'll sit at 70-80 all day if you can stand the racket inside. Car has a stage 1 kit with k&n inside the original box & lcb. Oh and it's on 10s rather than the standard 12s.

 

Don't think I've ever exceeded this, maybe 38ish. Very happy with that from an engine that was first introduced in 1951, think it's pretty amazing to be honest.

[Wazzah]

My SPI had a crook vacuum hose to the charcoal canister under the front wing. There is a section of metal pipe that rises to the right of the air cleaner and connects to rubber that then heads to the canister. Rover must have been low on rubber that day as it only just overlaps the metal pipe. Attention to this fixed the last of my idle problems and took my economy from 37 ish to 41 over the last 3 tank fulls.

[Screwdriver]

12.3L/ 100 kms for the latest city tankful. Yikes! 

[genpop]

check the electrical heater underneath the carburator, inside of the intake manifold (electricaly and manualy).Functionality of this is important on short distances.

[Alpenflitzer]

I am driving the SPI with 53 PS and get  47 to 44 miles per british gallon or 6.0-6.5 /100 km A major point is the engines compression. Did you ever measure this? And, I am using twice a year LIQUI MOLY VALVE AND INJECTION CLEANER: It is also used on my SAAB and the stuff is great. Injectors tend to get dirty and spray gasoline in one direction instead spraying in symmetry.

Roads: We have here many mountains and passes on and over the hills. This normally needs more gas because you shift form third to second and partially to the first gear and back.

Spark plugs ok? What color do they have?: