My 95 is running way lean help please

kozz167 · Jan 27, 2011

I have been messing with a lean 5.0 since last summer after I had to change out all the censers and EEC, MAF, distributer and ICM. But after I changed the intake manifold to GT40 stile it seamed to get worse.

70MM throttle-body
Tuned shorty's
X pipe
Cat back
255 Fuel pump
Fuel press reg set know at 40 psi was 50
timing back at 10
Bosch platinum 4 plugs
good wires cap rotor
stock 19 injectors new
the rest of the engine heads on down is stock.

Last weekend I tried a dyno pull and my AFR hit 17.6 at 3800 in 4th when she started to spark knock. My low bad gauge pegs out to full lean any time I try to get in it. She starts great and idles great, no over heating and no codes pop, some time a little back fire in the intake. How can I fix this?

MuscleInc1320 · Jan 27, 2011

honestly for one thing get rid of those bosch plugs. our cars run best with a copper autolite #25 or Motorcraft plugs. as for the car running lean i would say that you must have a major vacuum leak. which sucks in un-regulatedl. your car cant correct for this so it causes it to run lean. try spraying carb cleaner around the engine to look for the leak. the idle will change if you spray in the area of the leak. some shops can also perform vacuum leak test too

kozz167 · Jan 27, 2011

I did change to the Autolite 25s. I have already checked for vacuum and air leaks, but did not fined any. only other place I can think of is the under side of the lower intake.

MuscleInc1320 · Jan 28, 2011

well if its not a vacuum leak, fuel pressure or a tune up....its got to be timing. try rechecking timing by pulling the spout connector on the passenger side then reading timing. should be ten. you can try putting a vacuum gauge on it to. it be between 17-22 hg in

kozz167 · Jan 29, 2011

Ok fixed it.I had already looked at timing and vacuum leaks. After the plug change, yesterday I cleaned the MAF and she ran a liottle better, so I changed my thurmostat back to a 195 and little better, but still way lean, so I change the ETC and wala all my poer and more came back with no more lean condition. I can pull hard in 5th and 4th on the free way and she reads at about 12.5 to 13 AFR.
Thanks every one for the help. A Stiky sould probly be made for a lean condition since their is one for a rich condition.

Drive your stang hard every day thats the way they like it.