93bluestang

i put 24lb injectors and it seems to run real rich, it has an E 303 cam gt-40 heads cobra intake headers and so on...... i belive with all those modds a chip is needed mine does not have one. If i were to get one burned i was thinking from SCT would that correct the problem and i also just bought a MAF for 24 injectors. What do you guys think?

thanks

88 GT CONV

With the exception of engine start up and WOT, the computer monitors the sensors and keeps the injectors in open loop to achieve stoichiometric A/F ratio

mjr46

Not true......when the vehicle is in the warm up phase it is running in open loop or off a predetermined set of parameters stored in the ecm...and when at WOT it is in open loop.....after car reaches operating temp somewhere around 160-170....car goes into closed loop where sensor inputs are used to calculate a/f ....also the computer doesn't monitor sensors....sensors are inputs to the ecm...which the ecm uses and interprets and makes calculations and adjustments to the vehicles fuel and spark delivery based on key inputs such as coolant temp, o/2 sensor readings and maf readings on a maf car or map if it were speed density

93bluestang

so then why is it running so rich?

mjr46

what makes you think it is running rich???

88 GT CONV

Yeah MJR, I got ya. I think I got my open/closed backwards...You sure open = predetermined parameters? I thought that was closed loop. And i just said that the computer "monitors" the sensors toprevent a long explanation of drivability lol

88 GT CONV

Any smoke out the tail pipes? Unburned fuel = black smoke

mjr46

yes 100 percent positive...open loop vehicle is not running off of sensor inputs....you have the idea just had it reversed

93bluestang

the smell is pretty foul no i dont recall seeing any black smoke but i got like 5 psi of vac. i use to have between 17 and 20, before i changed the injectors

mjr46

You mean 5 in hg =neg psi in a sense..anyway if you have less vaccum after an injector swap ..are all the injector o-rings installed and seated properly?? rough idle?? any vaccum leaks...??/ all vaccum hoses installed back on upper intake??