Goose21sc

I recently purchased an '88 mustang LX 5-spdw/ bbk headers & cat back w/ flowmasters. To my knowledge the engine is stock other than that mentioned above. Problem is the engine is every so often while driving popping back, and also smells as if it is burning rich. However, when I hooked it up to a computer it gave a 041 "system running lean, and a 091 "ego running lean". So far i have replaced both oxygen sensors(or ego sensors), spark plugs, wires, coil, cap & rotor, took apart and cleaned the throttle air bypass valve, and replaced the tp sensor. After all this the problem still persists and the computer codes remain the same. Any help on this would be greatly appreciated.

Jugador1

im a noob on stuff like this...but i figuretelling themwhat octane you're running might be important...? wait for vfast to find this, hes a technical genius

Goose21sc

ooopps...ment to mention that...thks for noting that i didnt...started out running 87 octane, but since then I've been running the 93...

Jugador1

might be the problem...i dunno though. i recall someone saying something about old people run 93 on their buicks when they only needed 87 and it always smelled like gas cause it couldnt burn it all...but really...<IMG src=smileys/smiley25.gif border="0">i dunno<IMG src=smileys/smiley25.gif border="0"> </P>


[edit]oh basically i meant it might be too high an octane to ignite all the gas hence the smell...but id wait for someone smart to tell you.</P><edited><editID>Jugador</editID><editDate>37915.9269907407</editDate></edited>

Goose21sc

well like i said I've tried a couple tanks of 87 and had the same problem so I don't believe thats the case...but there again "i believe"

Jugador1

well then you got me. i dont know nothin bout fixing things...im just a kid. lol. sorry about your problems though. and if you get it with both octanes, might as well run 87 and save money! lol. well sorry i couldnt help

Goose21sc

i appreciate the effort

95Stealth302

I have the same problem with the smell and popping, I've been attributing it to just not having any cats, but is that the only factor. My computer says stuff is A OK.

horatio102

Perhaps a previous owner took certain liberties with the cats? Have you checked to see if they've been gutted? Also pull the ECM out of the kick panel and check to see if there's a chip plugged into the port - when I bought mine there was a chip for N2O in it that adjusts timing and fuel delivery iirc.

Also - is your air pump hooked up and working properly?

horatio102

You may also want to pull a fuel injector and read the part number on it. Take the # (if it's a ford number anyway) and find out if it's the stock 19lb injector, or if somebody swapped in a 24 or 30 (or higher, but doubtful).
Why you're getting lean codes if indeed it's running rich though... it would almost have to be some sort of botched electronic signal - engine thinks it's running lean so it adds more fuel.

Veeeery interesting.