Why is the Pulsar so thirsty?

[Jon Olds]

The AFM measures the air mass, and the ECU allocates a corresponding injector pulse width (with other inputs such as throttle position) . If the air goes out the DV, not into the engine, then the ECU will give the wrong pulse width. Won't it?

 

[skiddusmarkus]

MPG is mostly down to driving style.My work sent me on an advanced driving course that lasted 2 weeks then a further 1 week course to be able to assess the driving of my workmates, then a 1 day SAFED(safe and fuel efficient driving) course and straight away I saw improvements in my mpg.

Saving fuel is about being in the highest gear possible for your speed without labouring the engine and using the least throttle possible.Doubly so on a turbo car as once the boost starts building fuel pours in.Its not necessarily just about your rpm, as you could be at 3k rpm with very little throttle and be using less than doing 2k rpm but with a lot of throttle.Its a boring way to drive but it sure does save fuel on long journeys-I could get 50mpg out of my old clio 172 driving this way.

 

[MarkTurbo]

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

How does the ecu know when its off boost? Does it work it out from looking at what all the other sensors are doing as it hasn't got a direct way of reading the boost pressure?

 

[Trip]

How does the ecu know when its off boost? Does it work it out from looking at what all the other sensors are doing as it hasn't got a direct way of reading the boost pressure?

Ecu maps are RPM Vs Load. Like mark said, how does the ecu determine load ? is it a combination of sensors such as TPS and MAF readings ?

 

[PobodY]

Well, I've definitely learnt something new then! - How does it know if you're on boost (or does it just assume that when the MAF reading gets to a certain point to go to open loop)?

EDIT - Looks like I'm not the only one to ask this question.

 

[Fusion Ed]

The AFM measures the air mass, and the ECU allocates a corresponding injector pulse width (with other inputs such as throttle position) . If the air goes out the DV, not into the engine, then the ECU will give the wrong pulse width. Won't it?

Except that the dump valve only opens when the throttle is shut and the engine is usually in over run anyway. I never see a problem from it. What I do see problems frequently is with AFMs too close to the turbo causing issues as you come off boost.

I have a really nice datalog of this I may show later if I get the time.

 

[Fusion Ed]

How does the ecu know when its off boost? Does it work it out from looking at what all the other sensors are doing as it hasn't got a direct way of reading the boost pressure?

It knows from the amount of air going into the engine vs load. Air going into the engine is actually more important to know for an ECU than manifold pressure. People can just relate to pressure better than they can imagine airflow.

 

[Fusion Ed]

Ecu maps are RPM Vs Load. Like mark said, how does the ecu determine load ? is it a combination of sensors such as TPS and MAF readings ?

TPS is not used for load at all. Only mass airflow is, then that is compensated with engine temp and rpm. Thats pretty much it!

 

[Spikey]

i remember when i change the std rubber inlet for a stainless steel one it would not run properly and it ran better with the afm disconnected. which was weird. So i but it all back and it was fine. Still dont know why???

 

[PobodY]

You need to be careful Ed. At this rate you'll teach us all enough that we'll do our own tuning. :der::lol:

 

[vpulsar]

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.

I was getting 40mpg out of mine on long trips once my motec was mapped properly.



John

 

[Fusion Ed]

you can run leaner than 14.7:1 on light areas of the map and increase MPG some what. It increases NOx emissions quite significantly, but can make a noticeable difference in mpg, you will loose power in these regions however. Just have to be careful of EGT temps etc.