dianosing MAF vs O2 sensor problems

[Chris_in_NH]

hi guys,

i've been getting 1128/1130 codes for a while now. haven't done anything about it just yet, but i'm getting there! car is a MY97.

i have a friend with a PST2 and i'd like to know how i can isolate the problems that i'm having and the codes that i'm getting. the main physical manifestations of the codes are pronounced throttle hesitation when cold (all gears) even to the point that the CEL started flashing when i pushed the gas pedal down more to make up for the hesitation. the flashing CEL lasted for about 5 seconds. (i pulled over and the CEL stopped flashing. i let the car warm up for a few minutes - very cold weather, maybe 10 degrees F - and then it was fine.) i also get an idle surge up to 2-3K RPMs when starting the car after it's been sitting for a few days. also have hesitation around the 5K RPM range. i know this is a symptom of a bad MAF, so i've cleaned it a couple of times which seems to work for a while, but then i get the symptoms again.

what i'm wondering is what kind of numbers should i be looking for to diagnose either the MAF or O2 sensors being good and/or bad. i wouldn't want to replace the O2 sensors (or MAF) if they were in good shape. ($$$) my friend's car is a 2003 S, so i don't think i could just swap the MAF to see if that improves things. his is an e-gas, and mine is non-e-gas.

my diagnosis leans heavily towards the MAF, but i'd like to be sure.

any thoughts, advice? i'm also going to check the AOS to check for vacuum leaks/broken hose.

[Chris_in_NH]

bump

anyone? someone at least tell me to search the archives or something. :help:

[Loren]

P1128 Oxygen Sensing Adaptation Area 2 (Cylinders 1 - 3) - Rich Threshold

P1130 Oxygen Sensing Adaptation Area 2 (Cylinders 4 - 6) - Rich Threshold

What this means is that the DME can not add enough fuel to mixture to make it meet burn and emissions standards. In short - you are running too lean.

Potential causes for this are intake air leaks (such as loose or broken hose, a cracked /broken oil filler tube, or a bad oil separator) and/or a bad MAF.

O2 sensors just read the results of a bad fuel/air mix - so I doubt you have a bad O2 sensor.

This really has been covered here many many times. Perhaps try searching for "P1128" and "P1130" next time...