Hey guys, trying to help out a friend. He recently bought a 91 auto z28. Im not sure if its a 305 or 350. It has the auto so I was thinking it was a 350.

A couple questions. Should this be a mass air car? There is a mass air flow sensor, but no pig tail that I saw to plug into it?

The car was running ok, but recently it started to have a low end miss. Idle is decent. can feel a little bit of a miss, but not to bad. WHen you get on the gas the car breaks up and runs very rough. Its stalled a couple of times and then not started for days, but then started again.

What kind of things should I look for. Anyway to test certain sensors like the TPS?

 

check fuel pressure(clogged fuel filter) and spark(bad plug or wire) start there. im not sure about the mass air sensor,, i thought they where all speed density after 1987.

 

I was thinking about the mass air thing, My buddy told me it was a mass air meter. Im thinking it could be a IAT?

To me it feels like the car is leaning out, I was thinking maybe a bad O2, it seems to get better on the top end when you floor it.

Is there a schrader vlave on the fuel rail to check the pressure? I was looking at it in the dark last night and didnt see one.

 

89-92 cars are Speed Density (No MAF). Check the VIN. The 8th digit will be "8" if it is an L98 (350) car. I believe "F" is the 8th digit for the LB9 (305 TPI).

 

89 was still a MAF car, 90-92 were SD.....
the problem your buddy may be experiencing could be the distributor,i personally would replace the entire unit and do a full tune up on the car....also check the MAP sensor and the vac. line going to it.....

 

Like I said, 90-92's were Speed Density 89's were the year that lost the cold-start injector. Brain Fart. It's been a while since I owned a thirdgen.

 

it was a bad computer for me. Once I changed it problem over.