Have a friend who's 94 Firebird is throwing a DTC 44, Left Bank Running Lean. Found a exhaust leak -carbon- at the manifold y-pipe flange. Tightened it up can't seem to feel any exhaust coming out around the flange. Cleaned the o2 sensor, was replaced not too long ago.

Can't seem to find what is throwing the dtc. Sprayed the outside of the intake with carb cleaner to check for vacuum leaks. Getting normal MAP readings at idle, about 30-32kpa. Relatively new plugs, wires are about a year old.

About the only thing I haven't done is hook up a fuel pressure gauge.

The car has no AIR or EGR systems. Vacuum lines on the Intake have been capped off.

If anyone has any suggestions I'd appreciate it. Car has been running like this for a few months now and the guy keeps driving it. Trying to help him out but seemingly he never has any money for parts w/e.

He does have a bad oil leak coming from the driver side of the motor, assumed it was the valve cover, used a fel-pro rubber gasket doesn't really seem to be helping.

 

Clogged fuel filter? clogged injector(s)?

 

How long since you fixed the exhaust leak? Did you reset the code? It can take some time, a few days, for the code to disappear. Otherwise, sounds like something might be clogged or you have low fuel pressure. Won't know till you check the pressure.

 

Changed the fuel filter a few weeks ago. Don't know about the injectors told the kid to buy some inector cleaner. Gotta wait till another friend of mine comes over later today, to do the fuel pressure tests.

Did the exhaust leak last week, cleared the code. Pops right back up, I'm inclined to believe that the exhaust leak is fixed. Kind of wish I had a EVAP smoker machine, on the other had a few grand doesn't sound that appetizing.

 

How was the O2 cleaned?? they are very reactive to any sort of chemical which will cause them to go bad. Also i would say exhaust leak its got to be pulling in extra air somewhere. I find it very hard to believe its low fuel pressure due to its only setting left bank off.

It could be an injector clogged which you could simply switch left bank to right bank if you think that to do a quick check and if lean code switches banks you know. Same for O2 sensor. It might be time consuming but no money.

Also it could be an intake leak but you already addressed taht.

 

used a propane torch to clean the o2 sensor. I'll try switching the fuel injectors around, thanks.