I doubt that the hole in the y-pipe is causing any problems up at the engine. The passenger side O2 sensor may be getting a high O2 reading if it is pulling outside air up to it between exhaust pulses on that side... How close is the hole from the B2S1 (passenger side) O2 sensor? Have you monitored the STFT (short term fuel trim) and LTFT (long term fuel trim) for both B1 and B2? If so, does it indicate an overly rich (high STFT/LTFT) for B2 (passenger side)?

 

The hole is about 7-8 inches away from the Oxygen sensor
on the passenger side. I am not sure what you mean by

Have you monitored the STFT (short term fuel trim) and LTFT (long term fuel trim)
for both B1 and B2? If so, does it indicate an overly rich (high STFT/LTFT) for B2 (passenger side)?

I cannot drive the vehicle over 5-8mph. It just has no power. If you mean take the Oxygen sensor
readings in park or neutral without moving under the same parameters from above, I can do that.
Is this what you would be looking for? From above you can see that the Ignition Advance is way
out of timing. In the next week or 2, I was planning to change all 4 oxygen sensors, catalytic converter,
muffler, and tail pipe and probably now the Y pipe since it looks to be on its way out. I am not sure
how long all of these items are suppose to last. I have not gotten any codes but I figure preventive
maintenance might be in order if I really want to keep this vehicle. I hope to get it towed tomorrow
once AAA lifts the ten mile ban on towing. I will make sure that the EGR valve gets checked properly.
I have had the vehicle for 6 years, 80,000 miles and hope to put some antique plates on it some day.

Thanks Mark K

 

There are parameters in the PCM for STFT and LTFT. It does not matter if you are driving it or not, just what the values are. STFT & LTFT are perfect at zero. If they are higher than zero, then it means that the PCM is richening up the mixture to reach the most efficient fuel/air ratio as read by the O2 sensors. If it is lower than zero, it is leaning out the fuel mixture. These values are how far off of the programmed fuel map the PCM is operating. A high LTFT means that the problem is persistent and has been around for a while. If the LTFT is high on the passenger side and normal on the driver side (high and normal are relative terms as this is different for every individual vehicle), this may indicate influence from an exhaust leak on the passenger side. The fuel trims really tell the tale of what is going on with the fuel system.

As far as replacing the O2 sensors, the only two that have anything to do with fuel delivery are the two sensors between the engine and the Y in the y-pipe. The other two are just catalyst monitoring sensors and should only be replaced if a code is stored indicating there is a problem and the associated diagnostic procedure indicates the sensor is faulty.

I would agree that the timing advance looks a bit out there... I had a look at some of my old scans from my 2000 Bravada and I show hot, in gear, idle advance of anywhere from 12* to 25.5*. I did have an 8* reading which was right after opening up the throttle after being stopped, the next frame (just .8 seconds later) the advance was up to 29.5*. Comparing your MAF flow rates with those I have logged, they look to be in line.

 

O2 BANK 1 Sensor 1
Rich-Ln
Measured .495V

Ln-Rich
Measured .495V

Lo V for switch
Measured .295

Hi V for switch
Measured .595

Rich-Ln Switch Time
Measured .05s

Ln-Rich Switch Time
Measured .03s
There were also numbers from test ID $70,$71 $81 with max and mins
not sure what they exactly tell.


O2 BANK2 Sensor 1
Rich-Ln
Measured .495V

This was the only info available for O2 Bank 2 Sensor 1

Should it have given me the same info as the Bank 1 Sensor???

Thanks Mark

 

Hello Kyle,

I hope you have patience with me. I am a novice trying to do a professionals job.

I ran a customized diagnostic with the info I think you are looking for.
I went outside and let the vehicle warm up for about 25 minutes this morning.

Frame 1
These are in percentages
ST FTRM1 0.7
LT FTRM1 2.3
ST FTRM2 0.8
LT FTRM2 0.8

Rpm 597
IGN 20.5

O2S11 Voltage .220
O2S12 Voltage .520
O2S13 Voltage .650
O2S21 Voltage.110


Frame 3
I am pressing on throttle
These are in percentages
ST FTRM1 2.3
LT FTRM1 1.5
ST FTRM2 3.1
LT FTRM2 0.0

Rpm 1534
IGN 26.5

O2S11 Voltage .115
O2S12 Voltage .120
O2S13 Voltage .165
O2S21 Voltage .805


Frame 18
I am holding down throttle
and trying to keep it steady.
It is laboring at trying to hold this rpm
These are in percentages
ST FTRM1 13.2
LT FTRM1 5.4
ST FTRM2 5.4
LT FTRM2 4.6

Rpm 1783
IGN 33.5

O2S11 Voltage .940
O2S12 Voltage .890
O2S13 Voltage .825
O2S21 Voltage.905


Frame 56
I am holding down throttle
and trying to keep it steady.
It is laboring at trying to hold this rpm
These are in percentages
ST FTRM1 0.0
LT FTRM1 6.2
ST FTRM2 -3.4
LT FTRM2 0.0

Rpm 819
IGN 20.0

O2S11 Voltage .565
O2S12 Voltage .740
O2S13 Voltage .570
O2S21 Voltage .905
I hpe this is what you were looking for.
Off to work.

Thanks Mark

 

I am finally going to get it towed in tonight.
I will update over the next few days.

Does anybody have any educated guesses?

Thanks Mark K

 

Well the item that was causing all the problems was a bad distributor.
I am going to have that replaced.

The EGR valve was checked and it was clean.
At the same time I am going to change the Exhaust components
and all oxygen sensors. I am am putting a new Catalytic Converter,
Muffler, and tail pipe. I had a hole in the Ypipe which was able to be welded closed.

I get the vehicle back tonight. I will let you know how it runs compared
to yesteryear. My feeling is that the Distributor was slowly going. It was the original.
150,000 miles on it. I know that there are a lot of parts that can cause a loss of power.
In my case it was the Distributor. I hope to say problem solved.

Thanks - Mark

 

Mark, sorry for not getting back to you on this. I have been working on my K5 the past few days which has pretty much monopolized my time. The exhaust system should be here today with the new headers coming tomorrow.

To your findings, yes, a bad distributor can definitely cause some very odd things to happen. It likely is a bad gear on the bottom of the distributor, but too much play can also cause the timing to fluctuate. At some point I will put together a how-to on replacing the bottom distributor gear and shim it to the proper end play (next to none). I have a distributor out of a 140k mile Astro van (4.3L) that I am planning on using.

Let us know how things work out! Thanks for the updates.

 

This will be my last post on this problem.
I feel like this is an episode of Blazer Mythbusters.
Problem Solved.

I did not personally do the work on the vehicle. I have a friend who
Is a mechanic that I trusted to do the repair. Even though I have
The reading knowledge to have done the repairs, I don’t
Have a garage, tools or time to have done them. I live in
The Midwest(Illinois) and you would have to mighty
Brave and ambitious to make a reapair like this outside
In the cold. I am sure somebody has done it. My hat is off to them.


My friend pin pointed the distributor
As the part for all my problems.
With a new distributor the car now runs super fine.
I am not sure exactly what was the exact problem
With the old distributor. I purchased the whole thing
To cover it all. He did that repair first and said the car ran fine
As is. I had already purchased the exhaust system and Oxygen sensors as
Preventive maintenance for replacement. I figured they had probably close
To 100,000 plus on them. 80,000 for sure.


I put on a new Walker direct fit catalytic converter,
Muffler(Quiet Flow3) and tail pipe along with
4 new ACDelco (AFS105) Oxygen sensors.

The Oxygen sensors which were taken out
Also had markings on them as being ACDelco AFS105(all 4)
I am not sure if the 1997 Blazer came with ACDelco(AFS105’s)
When it was put together or not. I can only say that I never
Got a OBD code indicating that they were ever a problem. I changed them
As preventive maintenance. They looked overworked for being
Where they were, but the PCM never indicated any codes associated with them.
The old ones had slits on the sides. I think The new ACDelco’s had holes on the sides.
I am not sure what difference that will make but it is only an observation.
They looked plugged up with black and white residue all over. It was a wonder
That they were still doing what they were suppose to do and I was not getting
Any codes. My friend gave them back to me not telling me what position
Each came out. One of them had a lot of black soot on it more than the others.
The other 3 had a lot of white residue on them.

The vehicle has no hesitation or surging. I can floor it
At any time and get performance out of it. I can’t remember
What it ran like 6 years(80,000 miles ago) when I purchased it but
I am a happy Blazer owner again. I ran a new scan test
For those interested on the same diagnostics from up above to
Compare with what I had started out with.

It is pretty cold outside today
18 degrees 7:00 am. I started the car up and let it idle
for about 20 minutes to warm everything up before testing.

Here are the new readings.

Frame 1
This is at idle
These are in percentages
ST FTRM1 0.7
LT FTRM1 0.0
ST FTRM2 0.0
LT FTRM2 -1.0

Rpm 760
IGN 20.5

O2S11 Voltage .750
O2S12 Voltage .840
O2S13 Voltage .100
O2S21 Voltage. .340


Frame 7(3.2 seconds)
I am pressing on throttle
These are in percentages
ST FTRM1 0.7
LT FTRM1 4.6
ST FTRM2 3.1
LT FTRM2 2.3

Rpm 1202
IGN 34.5

O2S11 Voltage .855
O2S12 Voltage .905
O2S13 Voltage .885
O2S21 Voltage .880


Frame 18(8.2 seconds)
I am holding down throttle
keeping it steady.
The engine sounds good and easy to hold steady
These are in percentages
ST FTRM1 0.7
LT FTRM1 0.0
ST FTRM2 0.7
LT FTRM2 -2.2

Rpm 1947
IGN 36.0

O2S11 Voltage .665
O2S12 Voltage .860
O2S13 Voltage .125
O2S21 Voltage. 795


Frame 56(24.8 seconds)
I am heavy on the throttle
and holding steady.
The engine sounds good and easy to hold
These are in percentages
ST FTRM1 1.5
LT FTRM1 0.7
ST FTRM2 0.0
LT FTRM2 0.0

Rpm 2958
IGN 38.5

O2S11 Voltage .720
O2S12 Voltage .755
O2S13 Voltage .100
O2S21 Voltage .740


Frame 59(26 seconds)
I am heavy on the throttle
and holding steady.
The engine sounds good and easy to hold
These are in percentages
ST FTRM1 0.8
LT FTRM1 6.2
ST FTRM2 -2.2
LT FTRM2 4.6

Rpm 3651
IGN 40.5

O2S11 Voltage .750
O2S12 Voltage .865
O2S13 Voltage .260
O2S21 Voltage .700

Well in conclusion I can see by the numbers in comparison
That the new items from mentioned above have made the
Vehicle idle consistently at around 750 rpms, prior it was around 580 rpm
The Ignition Advance at idle with this new idle starts
Out at 22 degrees. I can plainly see that the Ignition advance
Now easily keeps up with the Rpm’s. It was cutting out before.

I am not sure technically what effect the new oxygen sensors and exhaust system
Has in the contribution to the new performance. I only know that the vehicle
Feels good to drive again. I hope this information helps out somebody in the future.
Thanks to all who contributed and viewed my repair.

Mark

 

Sounds all most like a plugged exhaust.