HELP! Trucking missing

I have 1996 Tacoma 2.7 and it misses under load. Also the scanner could not connect to pull the codes. Where should I start?

 

you need to get a new code reader or go to Autozone for free

 

I was sure this would be more interesting based on the title.

 

Might be a dirty injector. I'd start with testing coil pack and plug wire resistance first.

 

Scanner read that the 02 sensor is reading low fuel causing the fuel injectors to operate wide open. What is causing this?

 

Sounds like the injectors are at full duty cycle. Have you replaced the fuel filter under the truck? If not I would start there.

 

I found that the fuel pump was weak and I replaced it, still misses under load.I have not replaced the fuel filter yet, I did hook the scanner up and it shows the air flow is jumping all over the place causing it to miss. When I disconnect the MAF it stops missing under load so Im thinking it is the MAF sensor went or is going bad, thoughts????

 

How did you determine the fuel pump was weak? Did you measure pressure at the fuel rail?

If you unplug the MAF and the engine no longer misses that could very well possibly be the issue. Just be sure before you throw parts at it. An airflow surge could be a byproduct of the misfire. Check fuel pressure at the fuel rail and replace your fuel filter if you have not done so in over 20k miles.

 

Yes, checked fuel pressure at rail and read low, changed fuel pump and now higher at dead head.

 

That's good but there are many parts that control fuel pressure.
Injectors, fuel filter, pressure regulator, fuel pump and I'm sure I'm missing something that can affect pressure.

Anyway glad you have good pressure now. Have a look at the fuel filter and try tampering with the MAF if possible.
How did you determine MAF voltage?