The bubble on the PCV hose? Vacuum leaks suck (figuratively and literally); are you testing with pressure?
SOLVED: Another misfire chasing threads (2008 express van)
- Thread starter Tonyv__
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Tonyv__
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Yeah it’s a smoke machine. But the smoke is so light I used windex to confirm the location
Got it. Fix the hose and see if it makes a difference. Maybe keep smokin' to see if you find anything else.
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Tonyv__
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Just ordered a replacement on RA. Should be here this week
will keep this post updated until I find the culprit. Too stubborn to take it to the dealer like I said I would
Tonyrodz
Resident Resident
Hopefully that was the issue.
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Tonyv__
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So the vacuum lines didn’t fix the problem ( unless there’s more leaks I cannot find). Took the valve cover off today and looked at the rockers and springs. Everything looks tight and the rockers all seem to move up and down as the engine rotates. Learned how to read my live data and saw that my long term fuel trim was 10.9 on the high side. Also read that the intake gaskets are prone to fail and cause misfires so I ordered some gaskets and plan to tackle that this week. Does anyone know if I have to remove and replace the gasket on the valley pan as well (where the knock sensors are) ?
also ordered myself a scope to look inside the cylinder walls while I’m at at.
also ordered myself a scope to look inside the cylinder walls while I’m at at.
Are your LT fuel trims that high on both banks? Or is this one bank only?
Watch your STFTs at idle and note both banks. Then run it up to 2K rpm and see if the STFTs change much.
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Tonyv__
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This is at idle. Running temp 189 I’ll try it again tomorrow
what also confuses me now is bank 2 is cylinders 2 4 6 8 I believe my misfire is on the other side (bank 1)
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It doesn't seem to be in closed loop yet, but it should be based on your coolant temp. It looks like the upstream sensors aren't working yet, unless the STFTs are changing off of "0," but a steady '0' is suspect.
The passenger (B2) LTFTs indicated that the ECM is adding much more fuel on that side than the driver's side. I suspect the vacuum leak, if it's the cause, is on that side. You could also have a mechanically stuck injector with one cylinder pushing just air. Eric O just did a video on one:
Can you get a graph or number values of the B1S1 and B2S1 O₂ voltages? They should be jumping between 0.1 and 0.9 V.
The passenger (B2) LTFTs indicated that the ECM is adding much more fuel on that side than the driver's side. I suspect the vacuum leak, if it's the cause, is on that side. You could also have a mechanically stuck injector with one cylinder pushing just air. Eric O just did a video on one:
Can you get a graph or number values of the B1S1 and B2S1 O₂ voltages? They should be jumping between 0.1 and 0.9 V.
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Tonyv__
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I posted the entire live data from just idling…
a couple weeks ago I swapped the fuel injector from 7 to 8. Nothing changed. Would that rule out a stuck injector?
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EDIT: I can't tell if "O2S11" is "side" 1, sensor 1; or "sensor" 1, side 1. Doesn't matter for that one, but how to tell which one is the bank 2 sensor 1 reading? Does your manual show the abbreviations?
Do you suspect cylinder 8 or 7 of an issue? It could be just about anything on the passenger side, so I don't think swapping just those two injectors would be conclusive, except by chance or luck.
In the third pic, the S1 upstream sensor is at 0.450 V (red arrow), which indicates that it's not warmed up enough yet to work, or is essentially dead. You may want to swap the upstream sensors from side to side to see if the voltages follow or if there is something wrong with the sensor circuit. Or do some electrical tests to validate the circuit. I'm wondering if this issue could cause the trims on the driver's side to compensate, but I don't think they interact that way. S1-2 (passenger upstream?) sensor (maybe not the green arrow, but the one above it at 0.835v) does seem to be working somewhat, but graphs of those would be super helpful. The STFT on that side bothers me as it should be moving off of zero a little as long as the sensor is working properly. Do you ever see either STFT move off of zero?
An app like Torque Pro with a OBD dongle would allow graphing, as would some other apps.
Do you suspect cylinder 8 or 7 of an issue? It could be just about anything on the passenger side, so I don't think swapping just those two injectors would be conclusive, except by chance or luck.
In the third pic, the S1 upstream sensor is at 0.450 V (red arrow), which indicates that it's not warmed up enough yet to work, or is essentially dead. You may want to swap the upstream sensors from side to side to see if the voltages follow or if there is something wrong with the sensor circuit. Or do some electrical tests to validate the circuit. I'm wondering if this issue could cause the trims on the driver's side to compensate, but I don't think they interact that way. S1-2 (passenger upstream?) sensor (maybe not the green arrow, but the one above it at 0.835v) does seem to be working somewhat, but graphs of those would be super helpful. The STFT on that side bothers me as it should be moving off of zero a little as long as the sensor is working properly. Do you ever see either STFT move off of zero?
An app like Torque Pro with a OBD dongle would allow graphing, as would some other apps.
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RED TAHOE LS
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Let the engine cool off, get comfortable with a small flashlight, check the plug wires ONE @ A time by shinning the flashlight into each end of the plug wires as well as the distributor cap. The miss fire will leave a black sooty look in the connection area if bad.
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Tonyv__
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So in manual. 02s11 is bank 1 sensor 1… 02s21 is bank 2 sensor 1..
According to my scanner misfire is on cylinder 7. (Driver side)
I only warmed the van for about 10 minutes before I started scanning. Which I thought would be sufficient… I’ll drive it a little today and try to monitor some live data on the road. I’ve never noticed if the St fuel trim fluctuated as this is my first time using the live data. I’m learning how to use it.
If the sensors don’t improve with a little driving. I’ll try to swap the 02 sensors or even order new ones. I’m sure they won’t come out without a fight..
I’ll also give that video a watch tonight about the injectors
also wonder if any HF scanners have graphing. As anything on Amazon won’t be here until late this week…
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Tonyv__
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I’ve moved the wires around a hand ful of times and replaced the spark plug in the problem cylinder just to be sure. I’m almost positive it’s not a ignition problem at this point. But thanks for the input
So don't let the video sidetrack you, it's just an example of some tests that can be done if it leads to that. I think you mentioned that you tested all 8 injector circuits with a noid light, so the PCM/ECM should be switching the injectors.
When you fire it up cold, both banks' Sensor 1s should be sitting at 0.450v. Once the heaters and/or exhaust warm them up -- probably within a couple of minutes -- they should be switching rapidly over a range of 0.1 to 0.9v, especially as the RPMs change. Ignore the downstream sensors as those are only monitoring cat efficiency. If one of the upstream sensors continues to sit at the 0.450v level and doesn't change, suspect the sensor heater, the heater circuit, or the sensor itself. If the sensor heater is bad the sensor may start working if you drive the truck; idling probably won't heat up a sensor (with a bad heater) enough to wake it up.
Keep us up to speed with what you see.
When you fire it up cold, both banks' Sensor 1s should be sitting at 0.450v. Once the heaters and/or exhaust warm them up -- probably within a couple of minutes -- they should be switching rapidly over a range of 0.1 to 0.9v, especially as the RPMs change. Ignore the downstream sensors as those are only monitoring cat efficiency. If one of the upstream sensors continues to sit at the 0.450v level and doesn't change, suspect the sensor heater, the heater circuit, or the sensor itself. If the sensor heater is bad the sensor may start working if you drive the truck; idling probably won't heat up a sensor (with a bad heater) enough to wake it up.
Keep us up to speed with what you see.
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Tonyv__
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Ok I bought a scanner this morning from HF on my way to work. I recorded some data on the road. I’m gonna see if I can upload it to my laptop later so it’s easier to see instead of me trying to record the small screen with my phone camera.
when I leave today I’ll check to make sure the sensors are at .450v when I start up then watch from there.
appreciate you following through and helping me out
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Tonyv__
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@Fless
so with this new scanner I’m seeing reversed readings. I couldn’t get either one to rest at .450 my van must still be hot from this morning. But the 02b1s1 is bouncing up and down like you said. 02b2s1 is a little more unpredictable
So of course just my luck and no research. This scanner doesn’t work with mac. I was hoping to see the live data on a larger screen
edit. The windows software is only there to update the scanner. Not much more. So I’m only working with the little screen. I did notice my stftrm was fluctuating from 0.0 to negatives and above negative to low 2s then back to negatives. They did not stay at 0.0
so with this new scanner I’m seeing reversed readings. I couldn’t get either one to rest at .450 my van must still be hot from this morning. But the 02b1s1 is bouncing up and down like you said. 02b2s1 is a little more unpredictable
So of course just my luck and no research. This scanner doesn’t work with mac. I was hoping to see the live data on a larger screen
edit. The windows software is only there to update the scanner. Not much more. So I’m only working with the little screen. I did notice my stftrm was fluctuating from 0.0 to negatives and above negative to low 2s then back to negatives. They did not stay at 0.0
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Well at least it looks like they're working. Weird that the scanner has fuel trims for the downstream sensors. For B2 S1, does the scanner show a STFT and does it move around a bit? (The first pic has STFT for B1 S2, which I think is bogus.)
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Tonyv__
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Yeah I edited the post. The stft does not stay at 0.0 like previously. It hovers into the negatives and up to about 3
patiently waiting for my scope to come in and I ordered an intake gasket for the hell of it. Trying anything at this point
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Tonyv__
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So I scoped the cylinder and I definitely see some scratches but I don’t know when it’s considered to be failed rings. I pictured cyl 5 for reference and I also see some light scratching. The pic quality is crap so bear with me. I didn’t realize how hard it would be to take pics of a small screen with my phone
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