i've got a 98 blazer with just over 200k miles. it's got the regular v6 in it. i've had it for about a year and have had to change the battery and fuel pump. i also changed the fuel filter, O2 sensors and added a k&n air filter. recently i've had problems with it. it's idling at 500 rpms and sometimes sputters and hesitates when i give it gas. i've also noticed a little bit of black smoke when giving it gas. from what i've read, it seems like the fuel pressure regulator could be the culprit. i went to autozone and had them check the CEL and they printed out the results and the paper says as follows:
Fuel trim bank two condition.
explanation: The ECM has detected a rich or lean air/fuel ratio condition on engine bank two.
Probable cause
1. If bank one and two are set together suspect a fuel pressure condition or MAF sensor fault
2. Failed HO2S21 (Heated oxygen sensor - bank 2 sensor 1)
3. Ignition misfire condition
4. Fuel injector problem
5. Engine mechanical condition.
i'm not too sure what to make of all that honestly. i'd really like to get some input on this. i'm off the next 3 days and would really like to get this fixed. my ac compressor is also locked up so i'm gonna change that as well so i can get my truck back to a comfortable driving machine. help is greatly appreciated.

 

Here's a few tech articles you can run through:
MAF Sensor Cleaning
EGR Valve Cleaning
2nd Gen Fuel System Diagnosis

There are two fuel trim codes for bank 2:
P0174 - Fuel Trim System Lean Bank 2
P0175 - Fuel Trim System Rich Bank 2

If it's localized to one bank, I would not initially suspect a problem with the FPR, but a fuel pressure & leak down test would confirm/deny that as a cause.

 

i cleaned my egr and maf and it still ran the same. when the car is parked and i rev the engine it blows out something black onto my driveway. i examined the exhaust system and found a hole toward the rear of the catalytic converter. it looks like the hole was formed from the lower bracket getting rusty and breaking off. i noticed the hanger was also broken and rusty. here's a pic of the hole

could this be whats causing code P0174?

i notice when i start my truck it runs alittle better until it warms up more. that's when it starts sputtering more. i know the hole can't be too healthy but, could this be what's causing my truck to run so rough? i didn't mention this before but, the check engine light will come and go but, the condition pretty much stays the same. sometimes it gets alittle worse but then back to its regular rough state. info is greatly appreciated.

 

A problem after the cat wouldn't necessarily cause a lean code. A leak in the exhaust ahead of the upstream O2 sensor on the passenger side of the engine could.

 

soooooo....i've had a tranny leak for awhile, (not sure where) thinking it was upper in the tranny but, today while searching i found that the o2 sensor (passenger side) and one of the tranny lines were touching and the sensor rubbed a small hole in the tranny line causing the leak. i patched the leak but, i'm thinking maybe the tranny fluid may have gotten into the sensor and made it function incorrectly. they were touching right where the wires enter the sensor. it looks alittle darker than the driver side sensor. not sure if its really effected but worth checking out. kinda sucks because i replaced both sensors about a year ago while doing a tune up but, if that's the problem then that'll be great.

 

It's possible that the sensor was damaged. A scan tool capable of displaying live data would help in the diagnosis.

 

i'm not sure what kinda scan tool i need. would the regular scanners from autozone be sufficient? i was gonna rent one and i asked the guy if it was the type that i could enter codes so i could follow the link you posted above but, he said he didn't think it was.

 

As I said, you need to get a hold of a scan tool that is capable of displaying live data. What that means is that the scan tool has to be able to show the actual sensor values being read by the PCM. In your case, you want to look at the B2S1 HO2S output (Bank 2 Sensor 1 Heated Oxygen Sensor) and compare it with the B1S1 HO2S output. They should look very similar, but will likely not be in sync with each other, pattern wise. You will also want to view the LTFT2 & STFT2 (Long/Short Term Fuel Trim with 2 meaning bank 2).