ossett2k2

iTrader: (9)

I've been looking at the map on my V3 STI running ESL.
It had a recent remap when some 740cc injectors were fitted,the figure in the injector scale is 0.67 which to my calculations is for 660's. Ive worked out that the scale should be set at 0.60 for 740's.

Ive taken a couple of short logs and on tickover the FLFC is pulling about 10% out,on WOT there is no correction in the high load and RPM range but i cant tell exactly the AFR as some Tw@t stole my gauge! I really need to get another before i start playing with the fuel map. The map is pretty rich in those high load cells but not having the gauge is a problem.

It has a IAT fitted but thats only logging constant 22.5 degrees,need to check that but some **** stole my multimeter!

Its also over boosting and is a fair bit higher than the Boost targets but i should be able to sort that out,there was a couple of perished boost pipes so might of been that,not tested yet.

Do you think i should rescale the injectors to 0.60 or will that put fuel map wrong? I assume it was mapped with the scale set to 660cc injectors?

Cheers
Rich

piehole1983

iTrader: (7)

Hmm, I'd be inclined to get the AFR readings on the go first I think. If you change the scale to suit 740s it'll chuck more fuel in then won't it?

ossett2k2

iTrader: (9)

or would it run lean as the ecu thinks 660's are fitted?and like i say it's quite a rich fuel map anyway,dont understand why the mapper would rescale to 660's?

piehole1983

iTrader: (7)

In theory would stay the same now I think about it? As you're adjusting the scale to suit the injectors then the injected fuel quantity should stay the same.

That's if they are indeed 740s. Flow test perhaps?

ossett2k2

iTrader: (9)

I'm pretty sure they are 740's as the member i bought the car from has them fitted,he's a top lad so no reason to doubt him.
so in theory rescaling to 660's is just like putting a limiter on the injectors? Still don't get why you would tho?

piehole1983

iTrader: (7)

Well not really, I would think they'll still go to 100% if the fuel is required. I can't see that happening unless you've got a huge turbo supplying a load of air. It'll always call for the same amount of fuel according to the map, regardless of the injector, by just changing the duty cycle.

ossett2k2

iTrader: (9)

Ah i see so changing the scale to 0.60 which is the scale for 740's would have no affect? Its not a massive turbo but it is a healthy SC42 Twinscroll.

piehole1983

iTrader: (7)

Well it would but the ECU will just adjust the injector duty cycle slightly to maintain the same AFR if you get me. I reckon you could change the scale now without affecting the map at all. I don't see why it would affect it.

bludgod

iTrader: (3)

the injector scale doesn't always tally up with the actual flow rate in my experience. Often is the case that it's easier to lower the size to increase fuel (ecu thinks injectors are smaller so opens them longer to meet the fuel target based on amount of air metered by the maf or amount of air consumed based on speed density).

Say you suck in 200g/s of air, so the ECU goes ok i have 640cc injectors so I need to spray for X amount of time (+ or - latency and any compensation values). If you were to increase that scale value say to 740cc then the injection time would be reduced because the ECU knows bigger injectors need to be open for less time to meet the same fuel target. It's the same the other way if you drop the figure lower then they will stay open longer sending more fuel in.

The a/f corrections will be disabled when you switch to open loop so what your seeing there is normal, the car will be cruising around trying to make 14.7 (or whatever the closed loop fuel target is set to) and adjusting the values as it needs to - once you switch to open loop it just reads blind off the maf sensor (as the o2 sensor can no longer be trusted to give reliable results under boost).

I've seen a lot of maps where the flow rate doesn't match what the injectors are rated for, even on cars with STI pinks or other stock injectors. Doing it this way means you rely on the A/F corrections to sort things out on cruise and you can use a block/wider ranging MAF adjustment to line things up easier.

The alternative is to get the wideband going and set the scale to what it should be (based on flow test results - decent injectors will come with a report when bought new that you can use to get going on) then let the wideband show you where to adjust the VE table/MAF scale to line it all back up again.

If you get the wideband hooked up and it shows your hitting decent values on cruise and your getting enough fuel to meet what the timing table is asking for without knock then I'd say just drive on at it.

piehole1983

iTrader: (7)

This is what I meant lol

Seriously man, I'm giving you a call when I get my yoke back on the road.

ossett2k2

iTrader: (9)

Cool,just need the gauge,going to order tomorrow.
I'm running a mafless set up btw,so in open loop it will take reading from the map,there is a IAT sensor rigged up(not logging correctly tho) but I'm I right in thinking it's not used as a reference point for fueling?

bludgod

iTrader: (3)

yeh i remember you sayin your mafless/speed density but it's handy to explain both together if anyone else drops on the thread later

IAT sensor should have a compensation table to go with it (will have to nosey through the ESL software again to confirm what options it has), colder air is more dense so this would normall impact the VE of the engine. Rather than have 20 volumetric efficiency tables for various temperature ranges and interpolating between them - you just adjust the VE table based on the intake temp compensation (or manifold temp compensation if you wan't it to be really accurate - also belter for feeling out when your turbo is running too hot and costing you power) then the VE table is always "mostly right", when cruising you nail it down further with the A/F correction values.

You'll have to pick a temperature as your zero spot/baseline and configure the VE table to give you decent values, then wait for the temps to change and double check everything is still good. If the values are generally off a little then update the compensation table to make it good

Pie - yes sir give me a shout anytime we'll see if we can't extract some more ponietorques from your donkey

ossett2k2

iTrader: (9)

Great info as usual bludgod