87 2.8 MPFI 230K,
several weeks ago it started cutting out really bad, I doubt its the fuel pump, I replaced it about 18 months ago.

My scanner pulled these codes up, oxygen sensor, Maf sensor too low, and manifold air temp was 286 at start up in 30 degree weather. I replaced the manifold air temp switch, fixed that problem.

When checking the voltages on the MAF circuit, I accidentally shorted it with one of the leads of my meter. So I checked the fuse box and nothing was blown. I went ahead and replaced the MAF sensor and the MAF relay, i figured i might have damaged something. I also replaced the O2 sensor.
Now it seems not to cut out, but it still acts funny, the exhaust has a smell to it. Where the air enters the throttle body it has an oily residue, guessing its fuel?
Checking the regulator, that regulates the air/fuel ratio thru my scanner it fluxs back and forth more than usual. Ideally my number is a 128 (14.7 to 1) and it will go from 128 clear down in the 70's then come back up near 128, back and forth. I've never seen it have that drastic of a change.

The only code that appeasr now is a 34 MAF sensor too Low, ANd like i've said I have replaced everythign on the MAF circuit. Could there be a fusible link somewhere? If so how do i find it and replace it? Could I have shorted soemthing out in the ECM??
Help!!!! Thanks to all in advance. Mike

 

I also have a cracked Y pipe, right at the Y, before the O2 sensor

 

You need to get that fixed first.

 

For the oily residue, are you running K&N air filters?

 

no everything is stock

 

{oily residual} Then a good possibility that it is from the PCV fresh air intake side. the miles could be causing oil to be pushed out the intake line.

RBob.

 

Check your orange wire going into the maf relay....i believe it is supposed to be 12v before the relay and .3 after (check maual)...might be in the harness it'self....

Stan