ever since i bought my s4 rx7 13bt it had always had bad fuel economy i mean like 1/2 a tank to 100kms that was on the high way ive had it dyno before that and even before it was bad could it be the fuel reg or dirty injecters?????? when ever i start it up and let it idle it spit out heaps of black crap smells like fuel and i have two big black patches on the ground in my garage. i get about 200 odd kms to a tank any body got an ideas

 

clogged cat? never heard of a car throwing up. definately interesting. have you changed the fuel filter? should be an easy thing to do and wouldn't hurt. also run some injector cleaner through. bad o2 sensor also comes to mind. thats all i have for now.

 

i agree with jeremy, change the filter, in fact, do a full tune-up! i might suggest going a step further than running injector cleaner though. i'd suggest removing them and having them professionally blueprinted, cleaned and rebuilt (or get new ones). after that, i'd probably having the ECU retuned, lean it out downstairs, and keep it just "safely" rich upstairs.

what fuel pump are you running? also, which plugs do you use? and maybe you should think of getting an EGT gauge.