zex92mustang

My car is running lean you can tell by the way it idles and the way it smells. i have lots of fuel presser and good vac. and the timming is a stock10*. im always getting code 91 and 41 lean codes. i have cleaned my maf but its a no go. could i need a new maf. Pease help im going to drive the car off a cliff. thanks

Tims 88GT

before you drive it off a cliff tell me ill take it lol. take a step back and chill for a second, now what does the car smell like? how do you know its lean, if it is one of the codes you have what are they, how does it idle and what is the vac?

zex92mustang

haha the code is 91 and 41, my mechance said it smelled lean and idled like it was lean, my vac was at 15 at idle. i get the codes all the time when its running, my fuel pressure is a 43 at idle.

zex92mustang

oh and the gases burn your eyes like crazy, i keep hereing 91 and 41 means the car is rich but i thought it ment lean.

zex92mustang

oh ya one more thing, with the iac unplugged the cars idle will slowly come up to 1000 then drop to 700, it sounds like i got a crazy cam in it but its stock.as you can see i really want to get this fixed soon, thanks for the help

spudz

I really think maybe your car is running rich instead of lean... Go find another "my mechanic" lol. Um first guess would be maybe your O2 sensors BUT I THINK that the fuel pressure is a little too high... I don't think it should be over 40... Maybe your fuel pressure regulator???

zex92mustang

the O2s are like 4 months old, is did the samething with the old ones. some one said code 91 and 41 means the car is at its lean limits and so its rich is this true. and i tryed putting a hose on the FPR and sucking on it it wouldnt go under 41 is that right.

spudz

Well, those codes actually mean lean.... BUT when your car thinks its lean....it tries to make up for it by making it run REALLY rich. Sure there are no vac leaks???? Also if the new O2 sensors are cheapo parts house sensors, they are prolly bad outa the box.... ALWAYS use ford sensors on fords. Get your DVM out and measure the voltage from the O2 sensors with the car running. This is true on all cars....O2 sensors in front of the cats.... should be fluctuating from say 200-800mv or close. If they are stuck or stay under say 400mv they need replaced. 400mv and less is lean.. O2 sesors behind the cats DON't fluctuate as much. They stay around mid range. I dunno if this helps or not.. But I think your "my mechanic" needs to be replaced. BTW I am a mechanic... But I work at a GM dealership lol.

silver91gt

it sounds like you have a vacum leak.

zex92mustang

it runs crappy even befor the cars in closed loop. my fuel pressure is at 43 at idle that cant be right