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at 2500... do all the sensors have a similar pattern???

or is one still flat lined?????


18:45.7 Engine RPM 2562 rpm
18:45.8 Vehicle Speed Sensor 32 mph
18:45.9 Ignition Timing Advance for #1 Cylinder 15.5
18:46.0 Intake Air Temperature 109.4 F
18:46.1 Throttle Position 49.8 %
18:46.6 Oxygen Sensor Voltage (Bank 1 Sensor 1) 0.78 V
18:46.7 O2 Sensor Short Term Fuel Trim (Bank 1 Sensor 1) -2.34375 %
18:46.8 Oxygen Sensor Voltage (Bank 1 Sensor 2) 0.5 V
18:46.9 O2 Sensor Short Term Fuel Trim  (Bank 1 Sensor 2) 0 %
18:47.0 Oxygen Sensor Voltage (Bank 2 Sensor 1) 0.72 V
18:47.1 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 1) -3.125 %
18:47.2 Oxygen Sensor Voltage (Bank 2 Sensor 2) 0.34 V
18:47.3 O2 Sensor Short Term Fuel Trim (Bank 2 Sensor 2) 0



i still think...  vacuum leak...

if the sensor is still flatlining at 2500..  swap left and right.. see if the flat line goes to the other side.. if so.. bad sensor.. contaminated sensor..  

perhaps the rubber elbows for the purge valve near the back of the intake..

What is this valve? Do you have the 3.9L V6 and know where this is exactly

thanks  

0. Leak detect pump
1. Vapor canister
2. Bracket,
3. Duty cycle purge
4. Upper bracket
5. Lower bracket
6. Front
7. Rear, Federal
8. Leak detect pump
9. Hose
10. Filter
11. M.A.P. sensor
12. Ft oxygen sensor
13. Rr oxygen sensor  

more stuff near the fuel tank..

 

Thanks,  besides hearing a vacuum leak, and moving hoses around to expose a cracked hose, is there any other methods to use to find a leak?  

there are all kind of ways...

i usually feel the elbows..  if they are soft and spongy.. they get replaced....

if they are nice and rubbery .. they might be OK...   feeling along them with the engine running..

you can squirt some water around.    see if the idle changes...   you can also squeeze the tip of a spray straw flat so it mists.. and use something like brake cleaner sprayed carefully around suspected leaks..

professional mechanics have adaptors that screw onto the gas tank filler neck opening and fill the tank with smoke... thats the cool way to find leaks...

look for the smoke...  there are other places to inject it also.. like the intake manifold..  

one shop... one tech took some of the 1/8" copper tubing used for oil pressure gauge lines on chevy trucks.. put a tee in it..  fixed it so the smoke would appear to come out of his ears..   the long piece of vacuum hose hanging out his pants leg gave him away..   it was a great effect..

stant and a few other companies make a fuel system evap leak tester.. where they charge the evaporation system with a few inches of WATER pressure... and see if it holds...

one thing.. 23 feet of water is equal to 30 inches of vacuum...   this is the Maximum vacuum that can be applied to lift water... in the water measurement.. or mercury in the mercury measurement..   inches of water is almost always used as a pressure reading..  try not to confuse them..  i know you know this.. i just has to clear the air about it..  

would a cylinder leak down tester find a vacuum leak?  

NOPE...

that tests the piston rings sealing in the cylinder bores and the valves sealing in the cylinder heads..


spray it with some water from a squirt bottle...  with the engine idling...

this ONLY does not work if the air temp is below 32 degrees.  it just makes ice...


a leif blower and a airless sprayer can make snow at 25F...  

Here is some with Long Term Fuel Trim.  Looks like Bank 1 is Rich all the time...


 

wrong sample...

what do the oxygen sensor voltage wave forms look like...

see the one in the lower left.. thats not right..



can you post a fresh one of these..  with oxygen sensor voltages at 2500 RPMs..

it still looks like there might be a vacuum leak on one side.. but if you have ONE bad sensor.. it does effect the fuel trim calculations..  

i just want to see if the bank 1 sensor 2 is swinging.. similarly to the bank 2 sensor 2 sensor..  

I'll have to do another logging run with laptop once I get time.

I took out the gas cap to see if it would throw a code and it didn't so I am wondering whats up with that?  Ran the truck about 30 miles, no code. Any ideas?  

http://www.aa1car.com/library/o2sensor.htm  

I think it is, i looked over some other scan data I logged and it appears Bank1 Sensor 2 is moving. I don't have time to post it now but could email you an excel file you can look at.