1989 Pontiac Firebird Lean Code 44, Mass Ar Flow Sensor Cod

JSCHIERER

MEMBER
1989 PONTIAC FIREBIRD
V8
2WD
AUTOMATIC
124,000 MILES

I need some advice. I think I am on the right track. Currently when I start the car cold, the idle does not run and stalls. When I give alittle gas it will run at 2000 rpm most of the time and some times falls on its face. It will drop in RPM sharply or sometimes misfire. I did the common code retrieve with the jumper. I recieve a lean code off the O2 sensor and a MAF code. I did a pressure test on the fuel rail is it is fine. I did a flow check at the fuel rail and I get more than a pint at 30 seconds. I replaced the MAF sensor, checked every vacuum I could find and replaced questionable ones. I went ahead and changed out the O2 sensor for the heck of it. It ran ok for a very short period of time and the problems came back. I tried to find air leaks in on the manifold and currently do not see anything. I am thinking it could be a hard to find manifold gasket leak or possible faulty injector. Is that sound reasonable? Would a gasket leak set off a MAF sensor? I check numerous connections and all the grounds I can find. Please help.

1 Reply

ERNEST CLARK

MECHANIC
1,730 POSTS

I've personally never encountered a vacuum leak that set a code for a MAF, but I'm not sure it couldn't happen either.

A vacuum leak lets in air that the computer can't account for (MAF is how the computer calculates airflow into the engine)

Also, are you getting the misfire from the tail pipe or the intake manifold? Did you check your ignition system? (Including timing) I'd go ahead and do this first, just to eliminate it as a possible source of trouble.

Next do another pressure test. This time with the Key on/Engine off. Make sure the pressure holds steady for at least fifteen minutes.

This is to check for a leaking fuel pressure regulator and leaking injectors. If the pressure holds steady, then do a balance/drop test on the injectors one at a time. If these check out, then start looking at the other sensors of your engine, (crank/cam, coolant, MAP, TPS, etc.)