mudbog42

I have been battling these codes for a while now and cannot figure it out, so I have decided to ask for some help. It is a 2003 5.3l flex engine that I swapped into my 86 K-5. I am getting trouble codes p0101 (MAF), p0174, p0171, and the o2 heater malfunction codes.

So far I have tried:
- 3 different MAF sensors no change
-New MAP sensor
-Changed intake gaskets
-Checked over and over again for any vacuum leaks
-Checked grounds to MAF
-Brand new o2 sensors

Also when the truck is cold it moves real slow like it doesn't have enough power to move the truck, then after about 2 minutes it runs and drives perfect.

I disconnected the MAF when it was cold for a quick test and it drove just fine, plenty of power.

I am not sure what else to do here, any help would be greatly appreciated.

RibeiroBJJ

iTrader: (17)

Do you have access to a scan tool or tuning software? Is the PCM tuned or stock?

mudbog42

I don't have my own scan tool. I always go to the parts store to read my codes. The PCM has been tuned

72VenturaII

iTrader: (32)

The codes are related and probably caused by the MAF or a vacuum leak. If it runs and idles better with the MAF disconnected, you need a new sensor. A really dirty air filter can throw the P0101 code. Any air entering the intake that doesn't pass through the MAF will cause the PCM to send an insufficient pulse width to the fuel injectors (P0171, P0174, lean condition on bank 1 and 2). You really need a scan tool and a digital multimeter to troubleshoot to check Fuel Trim, sensor readings and signal voltages or frequencies to the sensor.

pdsq98gt

When you say "its been tuned", do you mean with a wideband, ve table and maf curve? Mail order? OR "its been tuned" I have a buddy with hptuners and we just coppied something off the net because we don't really know what we're doing?

mudbog42

I've tried different MAF sensors, 2 of which I borrowed from friends vehicles so they are known to be good. I do have a digital multimeter, I wish I had my own scan tool to use though.

The tune was a mail order. I had it tuned by Jims Performance.

pdsq98gt

It sounds like either the tune is way off or you have low fuel pressure. You said you've already made sure there are no vacuum leaks. I guess the injectors could be clogged too, but I would make sure that you get it tuned with a wideband on the car.