meangreenchevy

I had a code for bank 1 sensor 1 insuffecient switchs so I changed the sensor with a bosch. Car ran good and fine for a little. Now I have no codes but I have a stumble under load and if I blip the gas quick in neutral. I have an auto xray and I'm looking at the voltages for the first 2 oxygen sensors. The new bosch one reads from about .150 to .950 that's bank 1. Now bank 2 is reading from .060 to .900 ant sometims it stays around .075 for a sec. The bank 2 sensor has been changed before but I don't remember when. Could this be my stumble?

Injuneer

I don't know why, but people who have installed the Bosch sensors in the LT1's have reported unsatisfactory results. The prevailing recommendation is to use only the GM parts - Delco or Delphi.

The Bank 2 sensor hanging at 0.075V for a second may be indicating a true momentary lean condition. Maybe you have an injector that is failing or plugging, a valve that is sticking, etc..

Look at the long term fuel trims for the various load/rpm cells and see if they are similar to each other, or showing a "split".

meangreenchevy

Thanks injuneer always coming to the aid. I think I found the problem. Cylinder 6 wire had a small cut in the wire causing it to arch on the metal boot cover

Injuneer

Yup, a misfire dumps air into the exhaust and the O2 sensor reads lean.

Good catch.

meangreenchevy

hey injuneer i changed my wires and coil with msd stuff and still having the same problem. can you explan what you mean by checking the long term fuel trims i can read them but idk what they mean

Injuneer

Tell me what they are, for all the cells, left and right, and I'll tell you if you have a problem.

meangreenchevy

I just put 2 new ac delco o2 sensors in the lts and same problem. I'm using an auto xray and here is all the info its giving me
Fuel system 1 closed loop
Fuel system 2 closed loop
Load value 3.5%- 3.9%
Coolant temp 181
Short term fuel trim 1 14.0%
Long term fuel trim 1 25.0%
Short term fuel trim 2 -1.6%
Long term fuel trim 2 4.6%
Map sensor 14 in.hg
Engine rpm 850-920
Vechile speed 0
Ignition advanced 24 to 30 degrees
Intake air temp 125 degrees
Air flow rate 1.19lb/min
Throttle position 0%
2nd air status atmosphere/off
O2 sensor 1 bank 1 .200 to .700
Short term fuel trim 11%
O2 sensor 2 bank 1 .445
Short term trim 2 not supported
O2 sensor 1 bank 2 .085 to .900
Short term fuel trim 1-4%
O2 sensor bank 2 sensor 2 .445
Short term trim 2 not supported

Injuneer

That shows the long term fuel corrections are maxed out on Bank 1 (driver's side), adding 25% extra fuel, and then using the short term corrections to add another 14% extra fuel. Bank 2 is easilly within normal tolerance. So your problem is on Bank 1. The elevated long terms may be a response to a faulty O2 sensor indicating 0.075V, a faulty wire (short to ground), or a bad injector on Bank 1. It's also possible there's a major vacuum leak that only affects Bank 1 - leaking injector bottom O-rings, intake manifold leak on the left head, etc. Could be the valves are adjusted too tight on Bank 1.

The MAP sensor seems a bit low (14"Hg MAP = 16"Hg vacuum, if you are at seal level), but that may be a combination of the cam and the tune.

While the long terms on Bank 2 look OK, the scan data is showing 0.445V steady on Bank 2, and that usually means an open circuit, due to a failed sensor or a harness wiring problem.

With your data, all you're doing is taking a single snapshot. Since it's idling and throttle is not open, you're only showing the data for Cell 16. There are 18 cells, with a left and right LTFT for each Cell. That's why a data log is a lot more useful than a single frame of data.

meangreenchevy

Damn your an expert lol. And I thought my problem was on the bank 2 side. The rear are turned off with my tune forgot to mention that. The valves haven't been touched. The scanner I have has real time data but does not data log. Is it possible that I got a bad sensor out of the box on the drivers side? Should I put an old sensor on bank 1 and see if that helps?

Injuneer

I think you may have wiring problems. Did you check for burned wires? Since you have headers I assume you have O2 sensor extensions?

meangreenchevy

I do have extension but I did them using factory male and female connectors. I'm going to check the wires again but I don't think there burnt I was just under there when I did the wires and didn't see anything that stands out. So I'll check that and if that checks out ill swap the o2 and see if that changes anything and I'll check back

meangreenchevy

Put an old sensor in the drivers side and same condition. If I hook up a vacuum guage what should a normal reading be so I can compare what I have to what's in spec

joshdoty23

hey i have a question for the both of you...

so i have a 2000 z28 and i am having some major problems. i am throwing 9 dtc's. i dont have cats on my car and a cold air intake. so i am throwing the folowing:

1) P0102 Mass or Volume Air Flow Circuit Low Input
2) p0103 Mass or Volume Air Flow Circuit High Input
3) P0137 O2 Sensor Circuit Low Voltage (Bank 1 Sensor 2)
4) P0157 O2 Sensor Circuit Low Voltage (Bank 2 Sensor 2)
5) P0327 Knock Sensor 1 Circuit Low Input (Bank 1 or Single Sensor)
6) P0332 Knock Sensor 2 Circuit Low Input (Bank 2)
7) P0405 EGR Sensor Signal Low
8) P0420 Catalyst System Efficiency Below Threshold (Bank 1)
9) P0430 Catalyst System Efficiency Below Threshold (Bank 2)

it is sputtering super bad and bogging out on me. it wont go above 1800 rpms every so often and it chokes itself.... i am extremely stumped and font know what to do... can either of you please help me...
thanks

Wilson

My car shows 20-21 on passenger and driver side vacuum hoses and the needle is solid.

Driver side i pulled the hose next to the pcv valve.
Passenger side i pulled the connector off the intake that was going to the fuel pressure regulator.

==It should look like scenario #1==
How to Use and Interpret a Vacuum Gauge

Injuneer

If your scanner can read the barometric pressure and the MAP sensor, you don't need a vacuum gauge. Subtract the MAP reading from the barometer reading to get vacuum. 20-21"HG is "normal" with a stock cam. The wilder your cam, the less vacuum you will see at idle.