Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
1. Coil should be looked at (ie ohm test the primary and secondary sides of coil) along with sparkplug gap. Also use a sparkplug tester to see if spark is good (a loud snap versus a dull tic sound) and bright blue and jumps a gap on the tester turned most of the way out.
2. Is compression test each cylinder when engine is cold and when engine is hot to see if some valves are sticking from carbon buildup. (South main auto has a video on a truck misfiring and lack of power going up hill albeit it was more intermittent than your situation but you never know) further more this will see if your timing chain might be the cause of the vacuum in exhaust as well
I have replaced the plugs,wires,cap,rotor,coil,Ignition module, MAF sensor.
Here are 2 samples of one is on the highway about 60MPH no issues running fine, Then the other one is as I was getting towards the top of the hill, however because of traffic I wasn't able to put the full load on it so it wasn't missing real bad, I will take another sample tomorrow hopefully under a bigger load creating the extreme miss to get a better picture of the sensor readings when it gets real bad.
Again thank you everyone that is giving me advise on the different possibilities.
Apparently I missed a few replies so my bad. What Chad said is absolutely correct regarding the back pressure test results. So in resolving the misfire will/should take care of the neg pressure in exhaust. Sometimes I miss things /over think it lol
That test was done in front of the CAT, with the muffler disconnected.
Which CAT? I suspect your problem is on Bank 2.
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer." I have learned more by being wrong, than I have by being right.
That's the interesting part, I did 4 different tests,
1: Driver & passenger side before CAT
2: Driver & passenger side after CAT
Same tests above but with the muffler detached ALL with the same results.
However I did get a code P430 when puling the hill and the truck was missing REAL bad. It's interesting I found an article about the P430 with the follow description that matches my issue to the letter T "see below"
If that is the case i guest I need to determine if its a bad sensor OR a bad CAT.
What is the best/easiest way to determine that?Here are the typical symptoms that something is wrong when you have code P0430. Often, when it is only the oxygen sensor is the issue, you’ll feel no symptoms at all.
Mileage- May or may not suffer depending on how much or if the catalytic converter is clogged.
Loss of Power– It is a really strange feeling to drive a vehicle with a catalytic converter that is going out. Typically, they’ll idle ok and drive normal under a light load. Whenever the engine is put under a heavy load it’ll feel like it is running out of gas. It’s very similar to the symptoms of a bad fuel filter.
Service Engine Light– Often, this is the only symptom of the Chevy Silverado P0430 code.
I did try unplugging the MAF sensor, how ever I wasn't able to drive the truck, even though the idle was about the same when I put it in drive the Trans. shifted VERY hard into gear, then when I attempted to drive it down the street it ran really bad, so I pulled over and reconnected it.
I am also uploading a few more graphs while going up the hill.
All three were captured at the same time
Oxygen sensors voltage Bank 1 Sensor 1 & 2 & RPM
Oxygen Sensors voltage Bank 2 Sensor 1 & 2 & RPM
Fuel Trim Bank 1
Fuel Trim Bank 2
Your capture cuts off what sensors. ie; Bank 2 Sensor...
There are two. Bank 2 Sensor 1 and Bank 2 Sensor 2.
Same for the capture on Bank 1.
I assume by the readings that the red is sensor 2 on each bank. I don't want to assume. If it's the red then bank 1 sensor 2 is reporting lean it should be up around 700mv steady. Bank 2 Sensor 2 is bad as it is oscillating. Should be steady at 700mv.
Something's up with the O2's. I know you bought new. Did you change both sensors 2? Or just sensors 1?
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Yes the red is indeed the down stream sensors for 1 and 2, The sensors are one of the few things I haven't changed, I sort of stopped there and bought the Autel scanner, and started scanning the different parameters, so your thoughts are a possible flakey sensor(s) I have no problems purchasing new ones =, I would be so happy to solve this issue.
If ever have a few Min. to let me pick your brain on a few questions I would love to talk with you.
Have to test to find out if bad S2 02's or cat gone bad. S2's should not mimic S1's and you also have a pegged lean 02 on bank 1 s2. Normal would be for S1's to oscillate 100 to 900mv and S2's to be steady around 600 to 700mv.
Do you have any propane?
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Watch all four 02's while adding propane to intake. What readings do you get? Don't want to influence readings by saying what you should get, so let me know what reading you get.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
Ok good start. Run the engine at 2500-3000k rpm for several min. S1's should normal oscillate and S2's should go lean. I suspect S2 will still oscillate. While at high RPM introduce the propane and watch all 02's go rich. Hold for a min or two then stop the propane.
What we're looking for is the pattern of the 02's as they return lean when you stop the peopane. The moment s1 drops lean note when S2 drops. Should be about 4-6 sec. You should see a noticable space in the pattern. I suspect bank1 will have a good space and bank2 will drop at the same time.
Post if you can.
"an open mind let's knowledge flow in and wisdom flow out for a man who has neither never listens to those who have both".
Being wrong doesn't bother me, it's being right and not understanding why that does
