Hey, got my code scanned for my Cat problem, guy said engine was running too lean. I know this means too much oxygen, but could this code be misread by the 02 sensor because of the higherflow downpipe and cat I have?

 

usually a lean running condition is caused by a vacuum leak somewhere. which O2 sensor is reading this. the O2 before the cat, or the one after the cat?

 

jeez, I dunno. The guy at autozone deleted the code before I could check which sensor. What are common symptoms of a vaccum hose leak?

 

lean/rich codes would be set by the pre cat 02
with a vacuum leak i'd expect poor throttle response, high idle or rough idle, lack of power.

the bad news.... lean code could possibly be caused by the modified maf, and theres nothing else wrong.

 

one other possibility would be that theres an exhaust leak between the cat an manifold. i dont recall where the 02 is off hand, but even if its in the manifold, exhust pulses could draw air up to the 02 and set the code.

just one more thing to worry about :P

 

probably my new maf, it looks like a piece of **** lol

Ill be going back to the old one...anyone got any ideas how to clean a dirty one?

 

at our shop we use a smoke detector. it is 100% accurate and if you do indeed have a vacuum leak, it will find it.

 

where do you put the smoke detector? exhaust pipes?

 

you disconnect the hose at the brake power booster and run the hose from the smoke detector into the hose from the booseter to the intake manifold. if you do use this method, you will see some smoke coming from the air filter housing. anywhere else is a vacuum leak. i also forgot to let you know that any exhaust leak will cause a lean condition as well, as said above.

 

my system is clamped, but would a slight slight gap (there are none that I can see or hear) cause a leak? I will be getting it all welded soon but I am curious