Vems Nitrous and closed loop

[Tony C]

this year we are going to run with 150hp gas, and fingers crossed closed loop if i can,

Does the vems run closed loop at WOT???
if so how can i stop it lean back the fuel when the nitrous injects, it also injects extra fuel via a seperate injector at the same time giving a slight rich mixture, its this rich mixture i dont want the closed loop correcting if possible,
i have an identical map on the laptop that is open loop, but dont always have the laptop with me when out in the car 

[rob@vems.co.uk]

You can set the range that closed loop works across, so you can pull it out at a certain throttle percentage. Check Settings -> EGO (lambda) control and you'll see that theres a max TPS (%) value.
If you were to use Extras->WOT / RPM Actuators to trigger the N2O then you'd be able to ensure that EGO switched off at say 95% TPS, and N2O switched on at 97%.

[Tony C]

how can the vems trigger my gas then mate?

as i have a tps input to my nitrous controller do i go to the vems instead then?

do you want a link to the wiring diagram???

[Tony C]

here is the link Rob,

http://www.racetested.com/images/manuals/low_res/Maximiser_Manual.pdf

im using the second set up with the tps1 unit mate....

[rob@vems.co.uk]

Have you ever probed the voltage on the pink wire (that changes to a white wire on the Maximiser control box)?
Essentally I'd use the VEMS in place of the TP1, how we'd do that depends on wether the control wire switches to ground (i.e. you can measure a voltage between the wire and ground) or if the control wire needs a voltage applied to it (which we'd find out by putting a voltmeter across the control wire and ground and mashing the throttle to see if theres a voltage when the pedal goes down.)

[Tony C]

it must be an earth trigger mate,
because if you look at the previous diagram the white wire goes to a switch that goes to earth, 

[rob@vems.co.uk]

Obviously we'd want to check that for sure, but essentially theres no problem getting VEMS to trigger it from its TPS sensor
the nice thing is that using the single resource for the switching will mean that you'll know for sure that the UEGO feedback is switched off and when the N2O is on

Rob

[Tony C]

i like the sound of that, i will check next weekend with the multimeter,
and report back

[cliffb75]

How much richer is richer?

Unless you are going so rich you really can't use the UHEGO, then I would suggest stay closed loop and simply richen the target lambda map in the area you intend to use the nitrous.

Closed loop at WOT is a nice thing, particularly for protecting engines during fuel starvation such as fuel surge, fuel pump struggling or low battery voltage.

Closed loop EGT control would be nice here too (big hint Rob )

As would switchable maps in this case i.e. target lambda / VE table switch and maybe even ignition timing switch when the nitrous fires (thats another hint Rob... )

[Tony C]

could the ecu not have an input from the nitrous arming switch?
normal road use it stayed closed loop, but when the nitrous is armed it goes open loop at preset tps value for when the nitrous is activated???
im looking at wiring in a pressure switch to the fuel line so if the fuel pressure drops the nitrous dont flow 

[rob@vems.co.uk]

How much richer is richer?

0.7lambda, peak power is 0.75lambda but only pros should consider it.

Unless you are going so rich you really can't use the UHEGO, then I would suggest stay closed loop and simply richen the target lambda map in the area you intend to use the nitrous.

Closed loop at WOT is a nice thing, particularly for protecting engines during fuel starvation such as fuel surge, fuel pump struggling or low battery voltage.

Closed loop EGT control would be nice here too (big hint Rob )

As would switchable maps in this case i.e. target lambda / VE table switch and maybe even ignition timing switch when the nitrous fires (thats another hint Rob... )

Really not keen on switchable maps, you can't tell instantly what map you're on...  How good is the throttle switch, what happens if the switch stays on and youre at 0.7lambda all the time?
Your comments on closed loop EGT have been fed into the development team, and like the MAT compensation that you and James suggested they've been received well and its implementaion is in discussion.

[rob@vems.co.uk]

could the ecu not have an input from the nitrous arming switch?
normal road use it stayed closed loop, but when the nitrous is armed it goes open loop at preset tps value for when the nitrous is activated???
im looking at wiring in a pressure switch to the fuel line so if the fuel pressure drops the nitrous dont flow 

I'll see if this is something that we can do - the ALS stuff switches off closed loop.  You dont want the injectors to behave any differently as you have a wet kit that is meant to be handling the additional fuel requirements.

Rob

[Tony C]

Cheers Rob keep me posted mate, 

[Tony C]

im hoping to go to the track in mid march Rob,
so if we have something sorted by then i can give it a test run 
if you need any other info about my system just shout,

My tps1 unit is set at 85% if i am correct,

also whne we go mapped ignition can the vems take an input to retard the ignition???
as my n20 controller retards the ignition (mallory cdi unit) by 6 degrees at 70% activation,

I know im getting ahead of myself here, but if i had to wire the ecu plug for the nitrous tps and possible arming input would also run the wire for the ignition input too while ecu is out,

[rob@vems.co.uk]

The simplest way to do all of this at the moment is to have two configurations, road use and track use.  The road one would be what you have now, then a switch over to one that has retarded ignition and that switches off closed loop and turns on the N2O at a set time.

In the meantime we'll see where the development team want to take things

Rob