Bandit_287

Oh right,thought it sounded too good to be true.

MB

An extension cable is just that, and extension which you can tap into. So they don't make one for the Unichip as such.

The Unichip just needs the ignition and crank pos prom memory, plus power and earth. Pretty simple job.

s2konroids

Ah got mixed up, the harness i have is made for the vafc2 so i just plug in it and away i go.

Snake_s2k

I asked to a tuner, who told me that he installed it on a 2003 S2000. He anticipated the vtec to 4,000... what do you think about it? He made a dinamic (on the street) map of the car changing air/fuel ratio to optimase it at different speed and rev.
My question is? Is there a danger for the engine? Is it really usefull to have a vtec entry at 4,000 instead of 5,500? Probably on track yes, but on highway where I don't need vtec?

s2konroids

Hmmm IME/IMO the best vtec engagement point should be played with on a dyno, so set it at say 4.5k tune+dyno it and move it upwards until the torque lines intersect where it doesnt lose power/torque.

Too low and you lose power due coming off the first cam too early ie making power on the first cam. Also obviously if you were on a motorway you could be in vtec at say 80mph (guess) which would not be too good for prolonged periods of time for the car/MPG.

Lowering too much on stock manifold etc will lose power until you change the manifold for an aftermarket one, on the stock bits IIRC the best vtec engagement point is around 5.7k rpm's.

Long tubular manifolds reduce reversion and contam between exhaust ports (the exhaust pulse from one port will flow back into another port reducing exhaust port efficiency).

On my car it is 5200rpm where it made power this was the best place 'on my car' on a westfield (f20c dropin+with various mods on) it was set to 4500rpm for a linear power output due to being only raced on a track. The tuner should set it so it doesnt have a negative effect on the top end, worth noting you will lose the vtec 'kick in' feel somewhat due smoothing the fueling and engagement point. TBH with my VAFC2 piggyback at the vtec engagement point, this where i could of used to ignition timing adjustment for a few 100 revs.

Why didnt honda set it lower, well for the 'vtec kicked in feel' dip then jump and for economy etc etc.

IIRC stock vtec engagement point is between 6000-6200rpm, adjusting it is safe as long as its been tuned correctly (fueling not too lean, ignition not too far advanced etc).

HTH

AJ

Snake_s2k

I read something about close loop and open loop, it's not clear to me which one Unichip controls, and in that way. I read, but I'm not sure to have understood, that if you modifies open loop, close loop will condition, on a base map, your tuning set up, causing engine light on if some tollerance are touched.

Is there someone who could explain better what happens?

Thanks

MB

Only open loop fuelling / ignition is modified with the Unichip, closed loop fuelling is still done by the OEM ECU.

You don't want to modify closed loop.

s2konroids

Simply,

Closed loop pootling around using both o2 sensors so say town driving etc and foot below 50% TP (accelerator) position = partial throttle.

Closed loop is when in WOT (ie your going for it ) foot flat to the floor, TP >50%, ignore o2 sensor.

The unichip i pretty much 'think' they can map it for partial throttle too.

MB

I don't think it can AJ, and I can't think why anyone would want it to. Remember, it's a piggyback not a standalone.

There is virtually nothing to be improved on closed loop fuelling IMO. You aren't concerned with performance at closed loop.

s2konroids

Truth is i dont know for sure Mark, the greddy emanage can tune partial throttle but its preprocessing unit (directy to injectors etc, satisfy stock table parameters STFT etc), so it doesnt tune directly to the MAP sensor like 'I believe' Unichip used to do.

I believe unchip changed the way it worked and moved away from the MAP way of tuning, because IIRC 'Ninebolts' rang them up.

My J's ECU definetly felt better round town not putting my foot flat to the floor.