injectors

[iFurio]

While ago my 1.4 injectors broke, changed them for vtr ones I had laying about. Was only one injector that went wrong so what I was wondering will the car run with 3 1.4 injectors and 1 vtr one?

[Prickle]

You cant mix them.

All of 1/colour

[iFurio]

Any reason you can't? Would car not run? Should be better than over fueling7

[Ross]

Small differences (ie 215cc injectors replaced with 225cc injectors can be handled by lambda control. If only one injector is different, that cylinder will run rich or lean (depends obviously) and do you no good. If they're all changed the ecu can cope well generally but it won't know about a single injector difference.

[yr51ocw]

Small differences (ie 215cc injectors replaced with 225cc injectors can be handled by lambda control. If only one injector is different, that cylinder will run rich or lean (depends obviously) and do you no good. If they're all changed the ecu can cope well generally but it won't know about a single injector difference.

Im lead to believe that on these magnetti marelli ECU's that they go open loop at high throttle demands, so the ECU wont correct for injector differences @ WOT.

[Ross]

You're correct. I'm not qualified to say how that may affect the engine at WOT. Im not sure if it would. But I'm not sure it wouldn't either lol. Johns input again may be useful here.

[yr51ocw]

well the 16v engine is mapped to be circa 0.9-0.88 lambda at WOT (well mine certainly is on an standard engine) so by increasing or decreasing the injecotor size will change the fuelling at WOT by the same/similar %.

So a small change like the one in your example (215-225cc) would have a small effect on performance (probably not noticable)

[Gandi699]

I didnt think the cooking spec 8vs used magnetti marelli ecus? only the rallyes or xsis and 16vs?

[axsaxoman]

closed loop control (lambda correction ) will on the std ecu change to open loop the settings in base map ,above 75% throttle +over 4000rpm on a vts --
other ecu,s may do it at other power levels
with older type of ecu,s --narrow band lambda-- there is also max amount of correction it can give even in closed loop usaully between 10/20%
on the fly by wire ecu,s this is a lot smaller and a max adjustment it can make each time the ecu is turned on --aprox 7% -- this is called adaptive mapping and is to allow for worn sensors -- 3 plug ecu,s on saxo,s + all motorised throttle types c2 /206/ etc

it is only the very latest cars ,not saxo,s where you have closed open control at all throttle + rpms and only on cars with w/band lambda sensors .
most cars will go open loop at some point .
mixing injector sizes is an absolute NO as the fuel corrections are measured where all the cylinder exhaust pipes come together --so it will mean that some will be running rich and others will be running lean .
which is why when i see aftermarket ex manifolds with the lambda probe on one ex primary pipe I worry --
they are assuming that the cylinder they have it on is perfect and so are the others --
there are aftermarket ecu,s that you can adjust indivual cylinder fuelling + timing --but no std car has them ,although a car maker may offset cylinders slightly due to design problems
EG center cylinders run hotter due to less coooling ,but they always fit 4 injectors at same flow rate