P0100 Problem - Help PLEASE?

[SgtAbn]

Hi Guys,

I have a P0100 CEL code which means "Mass or volume air flow "A" circuit" problem in addition to my truck hesitates under acceleration and frequently stalls when I come to a stop or slow down. Any help would be greatly appreciated please.

Background info:
I have a 1999 T4R with California Emissions which means 2 catalytic converters and two O2 sensors, 293,000 miles. Until yesterday I had the following CEL codes:
-P0100 code mentioned above
-P0171 I don't remember the definition of this one
-P0420 "Catalyst system efficiency below threshold bank 1"
-P0440 "Evaporative Emission System"
-P0441 "Evaporative Emission System incorrect purge flow"

Here is what i did so far:
1) Cleaned the MAF, CEL codes persisted.
2) Replaced the MAF, CEL codes persisted
3) Replaced Air filter, CEL codes persisted
4) Replaced plugs and wires (with OEM), CEL codes persisted
5) Read that sometimes you have to replace BOTH O2 sensors at the same time, so I did that yesterday and did a 45 min test drive both on and off the highway.

The results are:
1) All CEL codes are gone except P0100
2) Hesitation under acceleration is noticeably better but still happens
3) Stalling when coming to a stop or going slow persists at the same frequency as before.

Anyone know anything about this P0100 or have any suggestions please?

 

[greenbomer]

The first thing I do is check the bat and alternator for proper voltage, the front cat on my 01 went bad at 137,000. If you have a obd 2 reader go for a spin and check out the cat presser.

 

[jgue467]

P0100 can be issued because of 1) Open or short in mass air flow meter circuit, 2) Mass air flow meter or 3) or the ECM.

Since you already replaced the MAF that takes care of #2.

So I would work on #1 and pray it's not #3.

Do you have access to an FSM? :cowboy:

 

[SgtAbn]

The first thing I do is check the bat and alternator for proper voltage, the front cat on my 01 went bad at 137,000. If you have a obd 2 reader go for a spin and check out the cat presser.

I do have one, I did not realize it would read that. Good suggestion - thank you.

 

[SgtAbn]

P0100 can be issued because of 1) Open or short in mass air flow meter circuit, 2) Mass air flow meter or 3) or the ECM.

Since you already replaced the MAF that takes care of #2.

So I would work on #1 and pray it's not #3.

Do you have access to an FSM? :cowboy:

Thank you for the info, I just got a FSM - Thank you.