Injector Duty Cycle on Stock S5 ECU?

[BenLewisMav]

I\'ve got a series 5 89 Turbo II and the setup is;
550cc stock primary and 1680cc secondary fuel injectors,
walbro 255,
apexi S-AFC fuel computer
apexi AVC-R boost controller.
(with a t4 turbo,external wastegate, bov, front mount intercooler)
 
What I need to know is will the stock ECU allow the injector duty cycle to go high enough (say 85%) to provide enough fuel, or will I need to still spend money or an aftermarket ecu? (and therefore mean that by buying the piggyback Apexi controllers i\'ve wasted money that I could of spent on an aftermarket ecu which can already control all of those aspects?)
 
 
 
 
(by the way, the reason for the large secondaries is so later I can pump up the boost on my T4 turbo and upgrade to 1000cc primaries and twin walbro 255 set up, and FPR if necessary -400rwhp target)

[Prof]

Stock ECU goes to about 85% on primaries up to 3800 RPM, nothing on secondaries. Then after 3800, Primaries run no higher than 40% and secondaries up to about 85%. If you\'ve put 1600\'s in there, you aren\'t going to have fuel worries (save for the pump being able to supply).

[grinder]

surely the stock ECU cant handle the extra size ??

i thought thats what the SAFC would do - you could up the fueling using that - or down in this case ( thats my plan anyways )

and if the ECU fires a set duty cycle ( for example at 4000 RPM it puts in 50% fuel ) then on 550\'s that would be say 275cc of fuel - but on the 1600 it would be 800cc of fuel - surely it would run REALLLLLLY rich ??

just my opinion - but to be honest i have NO idea ( just thinking outside the box as it would be )

Stu

[antnicuk]

i run 550 prims and 1680 2nds but with an apexi, i ran 380 rwhp with only 75% duty at stock pressure so you wont need 1000 cc prims.   With those 2nds you will have trouble fueling accurately without an aftermarket ecu for the reason grinder mentioned.

[BenLewisMav]

Cheers guys, great info.
 

i run 550 prims and 1680 2nds but with an apexi, i ran 380 rwhp with only 75% duty at stock pressure so you wont need 1000 cc prims. With those 2nds you will have trouble fueling accurately without an aftermarket ecu for the reason grinder mentioned.

That is true, but you can increase or decrease the amount of fuel pumped in for different RPM ranges, so, combined with the apexi boost controller which gives rpm based control of the boost curve I should be able to work it out nicely. e.g. have full boost kicking in around 4000 rpm, and then also increase the fuel pumped in at the same time..
 
However do you mean that it will cause problems like the primary rotor running lean because the duty has been lowered to stop the secondary flooding -if thats even possible..??
 
perhaps 4 x 1000cc would be more appropriate for even fuel distr?

[elford_tim]

perhaps 4 x 1000cc would be more appropriate for even fuel distr?

My understanding is that you\'d want fairly small primaries to simplify control at low revs/low boost as it\'s very hard to control large injectors accurately enough under these circumstances.

Given how prone rotaries can be to flooding I wouldn\'t want the injector equivalent of a firehose as primaries...

[sadgoth]

IMHO the aftermarket ECU would be your best bet, you\'d still need the boost controller so that wouldn\'t be a waste and then you\' have full control over all issues. If it came to it, you could always sell the S-AFC.


Thing is the ECU options for the FC are quite varied:
Microtech
Wolf 3D
Haltech
Apexi PFC (with the adapter stuff for the FD loom)
to name a few

but you could get yourself sorted on the ECU side for about £600 (or less) then you would have full fueling control.

[Prof]

Strictly speaking, Injector duty should be a function of 3 main variables - RPM, Manifold Pressure (Boost) and Throttle position.  There are also other variables like acceleration / deceleration, Water temp, Air temp which also play a part.  After market fuel comps or injector controllers only usually look at 2 of these main variables, and none of the secondary factors.  This is where an aftermarket ECU will help - as it knows about the other factors and can more correctly control fuelling.
 
Larger primaries make it more difficult to handle the idle control - as the injectors will hardly be on at all.  And you almost certainly want an aftermaket ECU if your not running the stock 550 primaries.

[grinder]

this seems a cheap solution :

http://www.nengun.com/trust-greddy/e-manage-blue

30,000.00 JPY=133.597 GBP

infact i could be tempted by that my self !! LOL

Stu

[grinder]

or this

http://www.nengun.com/trust-greddy/e-manage-ultimate

53,000.00 JPY=235.976 GBP

[BenLewisMav]

I guess the S-AFC wasn\'t really designed for Rotaries as you can\'t control the secondary and primary duties individually?
 
I presume that all of your standalone ECU\'s allow you to do that?

[grinder]

if you look on the USA forum - there is a whole section about the SAFC\'s

i gonna run one on mine ( already bought it ) - but i will only run 720 injectors

[antnicuk]

you can also control timing and a few other bits with an aftermarket ecu

[Prof]

If you go emanage - go with the ultimate - it\'s had independent primary / seconday injector control and leading / trailing ignition.  It will autotune injector replacements up to 850cc\'s, but after that you must adjust the fuel maps manually - but 850\'s all round will see you at 400BHP with the correct induction / turbo / intercooler set up.
 
By autotune I mean you put the new injector size in the table and click the mouse - the emange will then correctly fuel cut to restore the stock fueling levels based on the increased injector size - how cool is that !:cool

[grinder]

tis very very sexy matey !!

thing with the one that i mentioned - you might need to then get the harness from somewhere else

prof : did yours come with a FC specific harness ?