Why is the Pulsar so thirsty?

Perrin21

Member
I have been wondering why the pulsar is so thirsty when it comes to fuel. It has the ingredients to be more fuel efficient. It's light weight by modern standards and the 2.0 litre engine is one of the best. I am getting about 120 miles to a tank. Will a remap improve this? I don't expect miracles but how attainable is 30mpg?
 

Trip

New Member
fuel efficiency isn't just weight. for starters the drag coefficient is high. the faster you are going the more opposing force you are generating.

The engine is not what i call best compared to todays standards. No idea about its VE but good for its age.

the AWD system is also a negative point, it looses around 25% of its power in drivetrain losses.

Big wheels, fat tyres, old wiring and other old components such is ignition system also contribute to low MPG.
 

John

New Member
Its a 2litre turbo with permanent 4wd which is coming on 20 years old, its never going to be great on fuel, especially in city situations where its terrible. The R also has very short gears so even when your cruising on the motorway at 70 the cars ticking over at around 3k rpm which is hardly ideal for saving fuel.

You cant really improve the fuel efficiency, you should accept what it is and if you cant afford to fuel it then get rid, unfortuneatly its a performance car and thus has performance car like bills. The only real way your going to save bills is by driving like a nun and when your on a motorway only doing 55-60 mph, which kind of defeats the point in buying the car. The other solutions range from running skinny tyres (ruin handling) and lightening the car (added expense so not saving money).

The fact your getting 120miles from a tank means your either never off the gas or drive solely in the city or the car is seriously over fuelling. You should easily enough see 200miles a tank and anything up to 28-30mpg is possible if your on a long run on a motorway.
 

MarkTurbo

Well-Known Member
The standard ecu map is ridiculously rich in the mid range, right in the places where you think you'd get better fuel economy! I'll bet most 400bhp cars (providing they've been mapped properly) use less fuel under normal driving conditions than a standard car would ;-)
 

bracpan

Active Member
I totalt agree with Mark, I could easy get 28 to 30 on run across country to events...Its better now with more power then is was standard.
 
M

markwashington

Guest
As above, I saw significant gains in MPG once my car was mapped properly, I went from about 150 miles per tank to 220+ depending on driving style. I don't really drive much so most of my journeys tend to be longer ones hence the better economy.
 

Jon Olds

Well-Known Member
slightly off thread, but what does an atmo dump valve do for economy? I have the parts to convert mine to recirc as I'm thinking the AFR just after
gearchanges must be megger rich. (Air dumped that has passed the AFM) Or am I missing something?
Thoughts appreciated,
Jon
 

PobodY

Moderators
Staff member
I am getting about 120 miles to a tank. Will a remap improve this? I don't expect miracles but how attainable is 30mpg?
That is particularly bad. Mine usually averages 200 miles; 250 when I'm just going up and down the motorway all day (I was commuting to Stoke from North Wales); and about 180 miles when I'm belting up and down the back roads. - I'm not on boost all the time, but I'm not driving like a nun either.

A remap will definitely improve economy (for the reasons mentioned above), but you may have other problems; a poorly adjusted TPS or dirty MAF maybe? Perhaps your MAF needs to be re-earthed.

WRT to the dump valve, I'm not sure how much difference it makes. Doesn't the injector duty stop when the TPS is at the closed position? - I did have someone tell me that the reason you can melt pistons easily is dump valves... because it gets lean. That made no sense to me (but you do Jon), so I ignored everything else he had to say about these engines.
Perhaps it doesn't go rich for very long; I don't really see that recirculating it makes any difference because you've closed the throttle butterflies, and that's what caused the dump (or recirculation) of the air.

Obviously I'm happy to be set right on this.
 

Perrin21

Member
thanks for your help. im well used to poor economy on performance cars but its nie to know everything is running efficiently. Im going to organise a remap of the car soon and see how it goes. I do have some mods and im sure they will have affected the standard tune of the car.
 

danr

Member
engine running below normal temperature will lower mpg, dirty/knackered lambda, ecu temp sender will have an effect too. dirty airfilter wont help..
a decat is 'suppose' raise mpg, but would still need mapping if done. a cheap apexi safc or neo would help too.
 

Trondelond

Active Member
The ECU does dump fuel into the system if you're running without a recirculating dump valve. Noticeable from all the bangbangs during gearchanges and whatnot. As far as I know, it can sort of be taken care of during mapping, but the best option would be to recirculate the air. I don't know what role the TPS plays, but as the AFM has noted that air has passed (and isn't accounted for when vented to atmosphere) and it will throw in the appropriate amount of fuel for the air that the AFM has registered.
 

PobodY

Moderators
Staff member
Fair enough. - It just seemed logical to me that because the BOV is before the throttle bodies it will make no difference if it recirculates or not. Plus all that reciculating it does is put it back before the turbo; there's nothing to stop the pressure coming backwards out through the AFM or into the crank case (which probably flushes all the vapour into the PCV with a standard setup).

Mine doesn't bang during gear change; it does pop occasionally when I'm running it to about 6k before the change, but not all the time. Maybe that's just my exhaust.
 

Fusion Ed

Active Member
'bang bangs' are caused by lean on overrun, not rich.

Improving engine breathing/efficiency by means of decat etc etc will improve mpg. Driving style is 90% of the problem however. I have driven pulsars from Sheffield down here and got 38mpg or so + when the clutch was slipping meaning I could use no power!!

You can lean out the map in certain mid range areas, the main thing however is to try and drive within the closed loop area of the map, that is how you'll get most efficiency.

Around town however its going to be appalling. An example Motorway driving I'll return quite normally 40+mpg from my primera GT. London driving it can drop to about 22, all that stopping and starting...
 

Trondelond

Active Member
Interesting, I always thought it was the opposite. Never listen to people on forums.

What is the "closed loop" area of the map?
 

MarkTurbo

Well-Known Member
Never listen to people on forums
It's not until you've been around for a few years you realise how true that is! I reckon a big percentage of what you read on forums is rubbish posted by people that spend more time behind a keyboard than the wheel of their car ;-)
 

Trondelond

Active Member
It's not until you've been around for a few years you realise how true that is! I reckon a big percentage of what you read on forums is rubbish posted by people that spend more time behind a keyboard than the wheel of their car ;-)
That is true. I know a few of them here, be it regarding cars or other matters. Perhaps we should have a bullshit-ranking for each user on here. :D

But I'm wondering - why do you get bangbangs on a lean overrun? Shed some light? :)
 

Fusion Ed

Active Member
its lean over run, there isn't enough mixture to ignite, but builds up in the exhaust and then ignites in the system with a pop!
 

PobodY

Moderators
Staff member
Closed loop is <2000 rpm if I remember correctly; that's when the lambda sensor comes into play. Obviously If it's been disconnected (or is defective) that's not going to work.

I completely agree with Ed though. Sitting at a fairly steady engine speed (even about 3500 rpm which is not closed-loop) gives me much better fuel economy than when I'm on and off the loud pedal all the time.

I wouldn't worry Tronde; as I said, I was told by a mechanic that atmospheric BOVs make the car go lean, but as we've already established the only thing that should happen is it goes rich for a couple of cycles.

(I can probably win the BS rankings!)
 

Fusion Ed

Active Member
Closed loop is up to 5200 rpm in all off boost conditions. The ecu will try to maintain AFR14.7:1 in these regions.
 
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