Well, I'm not really sure of the best place to start with my troubleshooting. So, I'll give some history.

When I got my Blazer, the air box had been replaced with one of the large, cylindrical air filters and the MAF sensor was gone altogether. The lack of a MAF sensor obviously threw a Check Engine light, but the Blazer seemed to run fine otherwise. Then, about a year ago, the engine started to bog down and die at take-off. I replaced the plugs, plug wires, distributor cap, and rotor button. The problem went away and the Blazer ran fine until a few months ago.

I started noticing a miss at acceleration, so I decided that the lack of a MAF sensor may cause the air/fuel mixture to be off enough to prematurely foul the plugs, so I tracked down a MAF sensor and air box in a junk yard and returned my Blazer to the factory setup. I had the error codes cleared, and the Check Engine light went away. The Blazer seemed to shift a little smoother (I guess the system improved how much gas was sent to the engine based on load), and it seemed to run fine. Then, about two months ago the miss came back.

In the past week, the Blazer started to idle really rough after warming up and when holding it in place at a stop sign. There wasn't any noticeable loss of power; it just idled rough and missed occasionally during acceleration. I thought running the year-old plugs without the MAF sensor for a few months had fouled them again, so a couple of days ago I replaced the plugs again.

Now that I have brand new plugs again, the idle has smoothed out and the miss is gone. However, when I take off from a full stop the engine bogs way down and hesitates likes its going to die before it finally moves. It hasn't died on me yet, but it sounds close at times. I only have trouble at take-off; it runs fine going down the road. Also, it only seems to start doing this after the engine has had time to warm up.

It recently threw another code: P1133 "Heated oxygen sensor - Bank 1 Sensor 1 (H02S11) insufficient switching"

The most obvious answer would be a defective O2 sensor, but I don't want to dump a bunch of money into sensors ($54 per) and not be able to fix it. So, my questions are:

1) Are there any other common problems that could cause these symptoms I should check first? Or, is it most definitely the O2 sensor?

2) I've heard that all O2 sensors have to be replaced at the same time, but the guy at the auto parts store said that its not actually necessary. Would it be alright to just change the one sensor throwing a code?

3) Here's a dumb question, but at least its a simple one for you more seasoned mechanics. I know bank 1, sensor 1 is on the side of the motor with the odd-numbered cylinders. Is that the driver side or the passenger side? I can't remember how the cylinder count works.

I appreciate any tips!

 

I also want to add that I'm pretty sure its not a transmission issue; loss of power at take-off can also be caused by a transmission failing to shift down to first gear. My Blazer bogs down at take-off in both forward and reverse.

 

Im having the same issue with the rough idle/miss after warm up. on my 96'
I've only had my blazer for a week, It doesnt seem like it has the power it should,
It also has the very bad bogging and almost dieing, then the rpms fly up n goes,
Pretty sure we have the same problem, I read your description and said to myself thats exactly what my blazer is doing,
Except i dont have a check engine light yet..

So ill be doing some things this week and i'll let you know if i find anything.
But any tips from anyone else would help too!! lol

 

Once engine warms, disconnect the MAF connector and see if it drives better, if so, clean it.
Use MAF cleaner. dont touch the sensor elements
That is often the cause of bogs and hesitation.

#1 cyl is always the frontmost. Bank 1 is always the side with #1 in it.. not the 'odd number side'.

So, yeah.. the driver side.

'insufficient crossing' could be because the fuel trim is at it's maximum, or because the sensor is contaminated and slow responding. Given the long history of running without full data, the sensor may well be bad.

 

You can also try to clean the egr valve.

 

This was the first thing I tried and it made no difference. Its not the MAF sensor.

@Empire932:
I have a strong feeling this is the O2 sensor. If it was a fuel or air supply problem, to me it seems logical that both sensor banks should be throwing a code. Since its just the one sensor, I'm hoping that narrows it down to the sensor or one injector. I didn't have a CEL code until yesterday, but you might want to have yours scanned anyway. Since you just got it, there's always the chance that the bulb is just burned out (or removed; I've seen that too).

 

Well, I just changed the O2 sensor and drove it until it warmed up. Absolutely no change, and now I'm out $50.

I'm about ready to just push it off a cliff.

 

sorry, I wasnt trying to be obtuse. I saw where you got one from the yard and installed it, not checked it again after other fixes.

Only thing I can thing of now is MAP {can your scantool check it engine off against local barometer?}
TPS
Or timing

What happens when you accelerate from cruise speed?

 

I don't have any trouble accelerating from cruise speed. If I'm rolling it runs fine, accelerates fine, and travels smooth. It only bogs down when I take off from a complete stop.

So far I've had AutoZone scan for my codes, but I ordered an OBDII cable for my laptop last week so I can get some more in-depth diagnostics. Hopefully it arrives soon and I can get a little more info on it.

 

Its alright, I forgot to include I've already sprayed down the sensor with MAF cleaner and tried driving it with the sensor disconnected.