Is this a bad sensor or are my O-scope settings off?

[McKay420]

I'm trying to diagnose an issue with my Suburban and I thought I would test the camshaft sensor.  I used one of those cheap $30 o-scopes from Amazon.  I just need to know whether or not this looks like a faulty (hall-effect) sensor or if my settings are just off. It is a "pull down" circuit.  If I play with the vertical sensitivity settings, I can make the "noise" go away, but is my PCM going to interpret this noise as a valid signal or not?  I'm not getting any check engine codes, so I'm leaning toward the sensitivity being too high or something.  Sorry for the low quality pic...1 mb limit per pic is kinda inconvenient.

[tautech]

Yep user error. Full amplitude must be on the display

[StillTrying]

Sorry for the low quality pic...1 mb limit per pic is kinda inconvenient.

I'd be happy for the 1 milli bit limit to be reduced to 100kB, it's only a limit when you don't know what you're doing.

[Macbeth]

...and the fault is? The reason you suspect CKP is...? even the slightest bit of info?

I've had a CKP fault once - 90's Ford Fiesta, car would not turn over, CKP fault disables the car. Cleaned it and it was fixed forever until some scallies stole it and wrapped it around a lamp-post.

[McKay420]

Sorry for the low quality pic...1 mb limit per pic is kinda inconvenient.

I'd be happy for the 1 milli bit limit to be reduced to 100kB, it's only a limit when you don't know what you're doing.

Lol sorry I'm not a real fan of windows when it comes to photo editing and I had already had enough of google for one day trying to figure out my car problems

...and the fault is? The reason you suspect CKP is...? even the slightest bit of info?

I've had a CKP fault once - 90's Ford Fiesta, car would not turn over, CKP fault disables the car. Cleaned it and it was fixed forever until some scallies stole it and wrapped it around a lamp-post.

Figured since this wasn't a car problem forum that nobody would care for the details or even know what I was talking about.  It's a 2004 Suburban 1500 5.3l Z71 flex fuel with 290,000 (yes I'm aware that the problem may just be the mileage).  Low, rough idle with no misfire codes and moderate hesitation on acceleration, but when I floor it and it goes in to open loop, the full 295 hp takes hold.  Long term fuel trims are 22% on both banks and short term are at zero.  They were at 50% until I changed my intake gasket and took care of all vacuum leaks.  I've also replaced both upstream O2 sensors, fuel pump and filter, checked fuel pressure, tested injectors and coils, changed plugs and wires and changed my throttle body assembly and mass air flow sensor.  The vehicle sometimes stalls but only at idle and will restart 95% of the time on the next crank and for sure one more crank after that.  Problem seems to start as soon as the engine warms up for a minute and goes in to closed loop.  Acceleration drops fuel trims down to around 10% (I know it sounds like a vacuum leak but it's not), and unplugging my mass airflow sensor drops fuel trims to 0%.  I have tested the MAF sensor and it is functioning correctly so it has to be because open loop automatically runs rich.  According to factory settings.  Since it is capable of functioning at factory settings at 0% fuel trims, I'm thinking that there might be more to this than just high mileage (worn piston rings or cylinder walls, or a burnt valve, etc.) Some parts of the vehicle seem extremely well maintained, but others looked absolutely horrible, such as the area under the intake.

I guess I should mention that I had an unresolved crank, no-start a few months back that just went away.  Whatever was happening was disabling the fuel pump relay, because  I could get the car to start and drive by jumping the relay with a paperclip.  I'm also experiencing decreased oil pressure (20psi) compared to the 40 psi from earlier this year, but that could have been from the cold weather.  During heavy acceleration and while monitoring the PIDs with my scan tool, I am only able to achieve about 60% engine load even though I'm moving at a decent pace, 0-60 in 12 seconds (factory is 9 seconds).  That 60% load is also correlated to volumetric efficiency which should be around 85%.  Engine bay sounds like a diesel, but I've checked the rockers and lifters and they seem ok, but I'm hesitant to remove the heads since I don't have the money for a head gasket right now and I've never done it before so I'm a bit hesitant.  Lastly, I haven't checked the exhaust back pressure, but I can't hear air hissing through the cats or anything and the exhaust flows strong and smooth.  When a piece of paper is held by the exhaust, it does not suck it in like there is a bad valve, but there is an abnormal amount of moisture coming from the exhaust.  I know water is a by-product of combustion, but it will make a piece of paper soggy in 10 seconds.  I am not burning or leaking coolant or oil, so I have no idea what this is all about. 

So I came to the crank/cam sensor conclusion (tested both now the proper way and they're fine) because I'm just running out of ideas.  Next step might be tearing down the engine for a total inspection/overhaul.

[Brumby]

I'm not a mechanic, but I've done my fair share of work on my own vehicles over the years - including head replacement.

When you say "tested injectors", did that include checking fuel flow and spray pattern?

I ask because I have a dual fuel vehicle (LPG/petrol) and if I run it on LPG for too long (ie over a couple of weeks or more), when I switch back to petrol I get very much the same symptoms.  I can fix my problem by running on petrol for a while to flush the injectors with fresh fuel which washes out any gummy build up, saving the effort of an off-vehicle injector clean.

Another thought is whether you've cleared the block learn of the ECU - just in case it has learned some bad habits - though this doesn't explain what caused the bad habits.

I still have a little niggle about the injector spray pattern, though.  Open loop is going to drive the injectors to pass more fuel, so even with compromised delivery, the extra fuel allows for smoother running.

[McKay420]

I'm not a mechanic, but I've done my fair share of work on my own vehicles over the years - including head replacement.

When you say "tested injectors", did that include checking fuel flow and spray pattern?

I ask because I have a dual fuel vehicle (LPG/petrol) and if I run it on LPG for too long (ie over a couple of weeks or more), when I switch back to petrol I get very much the same symptoms.  I can fix my problem by running on petrol for a while to flush the injectors with fresh fuel which washes out any gummy build up, saving the effort of an off-vehicle injector clean.

Another thought is whether you've cleared the block learn of the ECU - just in case it has learned some bad habits - though this doesn't explain what caused the bad habits.

I still have a little niggle about the injector spray pattern, though.  Open loop is going to drive the injectors to pass more fuel, so even with compromised delivery, the extra fuel allows for smoother running.

I tested the resistance and got 12-13 ohms each and also used a modified ATX power supply to pulse some pressurized carb cleaner through them using some different sized fuel lines and heat shrink tubing to connect the tiny straw to the injector nozzle, then I flushed them out backward using the same technique.  I spray patterns were kind of ok, but if it REALLY matters that it is in a fine mist rather than a misty spritz, then I might have a problem.  Thinking about ordering an ultrasonic jewelry cleaner to break up the varnish.  I may test the flow rate today now that I have a fuel gauge.  Just need to figure out a way to pulse each injector for an exact amount of time for testing accuracy.  Both fuel trims are so similar that each injector would have to be nearly as bad as the others which seems unlikely.  How much do you think carbon buildup in the ports near the intake valves matters?  I read something about a "sponge effect" where the carbon soaks up the fuel and causes a lean condition.  I'll definitely look in to the injectors though.  It was one of my next two things to re-check.  The other was testing for spark consistency with a hot engine, since coils apparently act up when warm most of the time.  Lastly, I never run E85 or anything other than gasoline, except last week I threw in a couple bottles of isopropyl alcohol to see if the octane change would make a difference.  It didn't. 

[McKay420]

Since you got me thinking about the injectors, I realized you are probably right.  Here's my theory...I believe this is called a "port injection" system correct?  Regardless of what it's called, I know that the air has to pick up the fuel on the way by to carry it in to the cylinder.  At idle, the air flow rate is rather low, so if the injectors aren't atomizing properly, the slow moving air at idle would have a hard time carrying the fuel to the cylinder.  As soon as I rev the engine, my fuel trims drop, which also makes sense according to my theory.  Richening the mixture like it is in open loop would just compensate for this effect at idle.  The only thing that doesn't make sense is my air flow rate, or volumetric efficiency/engine load isn't as high as it should be at WOT, but I assume the injector pattern is probably pretty important, but just not as noticeable at higher revs.

I don't believe I answered your other question, but yes,  I've disconnected the battery and touched the negative wire to the positive terminal in order to drain the capacitors in all electronics to reset the PCM.  Fuel trims are very strange on this vehicle compared to what I've seen online.  It doesn't matter how far you drive, long term trims are VERY active no matter what.  The long terms don't fluctuate, but they react instantly to large changes in short term trims, if that makes sense.  Other vehicles I've heard about can take tens of miles of driving to straighten out trims.  The way my Suburban does it seems much more efficient.

[den]

First of - hall signal is dreadful. Find someone with a proper scope to make sure it is the signal, and not scope problem. Did you try disconnecting the hall? It could run in a dual spark mode, but depends if this function is built in.

About the trim. Looks very much like air leak between throttle and intake valves. Did you check everything? Sprayed brake cleaner to questionable areas? Checked each vacuum pipe and brake booster?

Why does it sound like a diesel? Really? This is something to check too. Did you check your timing belt/chain?

Also - check the leaks in exhaust system upstream lambda sensor - if there is a leak the sensor gets oxygen from ambient air and hence thinks it's lean. Improbable in your case, but an idea.

If injectors create mist (with droplets, but still mist) and not just jets - it's OK. If you have jets - not OK. The exact 22% on both banks can also be due to the fact that it's a limit, maybe it simply can't go over 22%.

The wall wetting effect (same idea as the "sponge" thing you are talking about) is relevant only in transient phases. It cannot suck fuel infinitely. Also this oil sponge forms in Direct Injection engines, not sure I have ever seen it in PFI.

To comment on the load parameter you are talking about one needs to know what it is - how it is defined.

[PChi]

At that mileage I would check the cylinder compression. Testers aren't that expensive.

My Vauxhall (General Motors) Astra engine was severely down after 90,000 miles which I had from new. Partly due to constant abuse.

[Gregg]

A worn camshaft could be your entire problem plus as den said, check your timing chain.  How is the oil pressure which is needed for the lifters to stay pumped up?

[McKay420]

Den- So you think that the sensor may be bad?  I went back and adjusted my settings to get the whole signal to fit on the screen and it straightened out in to a perfect signal.  I think maybe I was somehow amplifying some ground noise (I have a 3000w sound system) or something.  I don't really know what I'm talking about when it comes to that stuff so I might be wrong..  I haven't gotten to the point of disconnecting it, since it's kind of hard to access without removing the intake manifold.  As for the air leak, one of the first things I did on this overhaul was removing the intake manifold and replacing the knock sensors and harness.  I also cleaned it up extremely well except for inside the actual ports where the hard, crusty carbon is.  I wasn't sure if it would be bad if any of it went in to the cylinders.  I had a shop vac hose shoved in each port as I cleaned around them, though.  As far as I could see, the intake valves were very shiny and didn't seem to have any carbon.  I had just run some Seafoam through the engine, so maybe that's why.  Seems like those detergents would remove deposits from hard metals like whatever the valves are made of compared to the iron block, which seems very rough and porous especially in the ports.  Is this some type of acid erosion caused by old oil?  I don't think the previous owner kept up on oil changes at all.  They had also used silicon sealant to try to seal the manifold leak.  Apparently silicon is a no-no anywhere near the path to the O2 sensors, as is Seafoam.  I have since replaced both upstreams and I torched off the residue from the best functioning remainig old O2s and used them behind the cats.  All O2 voltages seem normal, but not fluctuating 3x per second as they should be.  I see maybe .3v-.8v-.3v and so on once per second.  It may just be my cheap Chinese wifi code reader though.

I have sprayed all possible vacuum leak areas with carb cleaner, propane, and water with no results.  I even removed the evap solenoid and plugged that with my finger to rule that whole system out (not sure if I'm correct in how I tested that, but it made sense at the time).  I believe it sounds like a diesel because I may have a leaky injector that I discovered tonight and that is probably thinning out my oil, which sometimes is only at 20psi at idle, when a couple months ago it was always at 40.  I can only hit 40 at WOT now when I used to get 80psi.  I need to put in some Mobile 1 synthetic and a nice Fram filter, since the last time I changed the oil I skipped the filter because I didn't have the proper tools to get it off (my idiot mechanic over-tightened it).  I'm probably gonna order a special tool or just jam a screwdriver through the side and twist it off.  I also have ramps that will make the job much easier and it's finally getting warm out.  The timing chain in these vehicles is very short, so the "stretch" would be minimal because of the small number of links there are to wear out.   Plus I think I have variable valve timing, so doesn't it rule that out in a way?  At idle, I get +18 spark advance and up to +50 at WOT.

Checked the exhaust as best as I could for leaks and it seemed good.  No hissing from the cats or muffler either.  Still a large amount of water coming out of the exhaust though.  A very unusually large amount...    I have not checked the injector spray pattern, but tonight I tested out the flow rate.  I thought my method was creative, but it almost ended badly.  To get a consistent pulse, I wired an injector plug to one of my turn signal lamps and hooked up my fuel pressure gauge and primed the system to 44psi (4psi below spec...I just realized this).  After priming to the same value on each injector, I turned the turn signal on for one full pulse and read the pressure gauge and all injectors ended at 5-6psi.  One injector, however, began to leak pressure as soon as I hooked it up.  I did not pulse it, but just hooking up the harness somehow made it open and stick a little bit. Pulsing it a few times made the leak go away so I could resume testing.  I'm sure you've already guessed that what I meant by almost ended badly, is I hydrolocked my number 1 cylinder because before I started the test, I did not realize that the turn signal lamps were constantly on with key on, engine off while the automatic headlights were on.  There is now way to prevent the turn signal from coming on when the key is turned on to prime the pump, so I left the key on and turned the light off with the switch and primed the pump manually through the relay socket with a paperclip.  I used pins 30 and 87 to do this, I believe.  Bottom left hole and top right relay hole.  I probably primed the pump 10 times before I realized what was happening each time I used the key.  I didn't think the fuel would sit in there that long, but looking back, I should have known.  I only attempted to start it twice before coming to the hydrolock conclusion.  The engine did not fire, so no damage was done, but it did make a scary "clunk".  I pulled the spark plugs and was met with a large amount of fuel only from cylinder one. I then used a big crescent wrench to hand crank the engine and get the rest of the fuel out.  Engine fired right up, but the weird thing is, after driving to the store and back, my fuel trims are now down to +7%.  It seems to change from day to day.  Most days seems to be 15% or so.  It's never gradual and seems to change instantaneously at startup or something.  I never see the change happening.  Lastly, I'm not too sure on the load, but I think it comes from the MAF and crank sensor (RPM) readings.  I've also read that the TPS and MAP may play a part, but I know the curve on a graph very closely follows the MAF rate and volumetric efficiency.  I don't have sources to prove this, but I've read that your air flow rate should equal 80% of the factory spec horsepower.  Mine is rated at 295hp, so I should be getting 236 g/s air flow at WOT and I can only get up to around 185g/s.  Remember that the MAF is a refurbished Delphi and I tested it and it's within spec at idle and the digital signal changes smoothly without glitches.  Something is basically stealing efficiency and not allowing the engine to pull in more air simply because it's not able to pump it in.  If my piston rings are worn, which they most likely are, I think putting in a higher quality oil to replace the fuel contaminated oil that is in there.  This should in theory fix the oil pressure and give me much better compression.  I need to fix the injector leak first though.  I hate to admit this, but I put in about 1/4 bottle of Seafoam in the oil, but didn't realize you do that BEFORE your oil change and not after.

PCHi-I have not gotten around to a compression test yet, but I did rig up a tester that I could only fit in 2 spark plug holes and it only went to 100 psi without adding oil, but on the 2 cylinders I was able to test, I got well over 100 on the first crank.  Since fuel trims are even on both banks and both cylinders I tested were on the same bank, I think my compression is probably withing spec, but may be suffering due to the thinned oil/oil pressure issue that I probably created and made much worse tonight after the hydrolock.  The oil will probably continue to get thinner at an exponential rate, due to acidity and oxidation taking hold.

Gregg-I had no idea that the lifters required oil pressure to be pumped up, but the AllData manual says the spec is 6psi at 1000rpm, which doesn't seem right, especially when the norm seems to be 40psi at idle.  Everything does seem to point to thinned oil, which could be mimicking bad compression or a timing problem as far as my level or expertise (or lack of) tells me.  As for the camshaft, worn lobes do seem to be an issue on the Vortecs, so I may have to look in to this if the injectors aren't the problem.  The fact that my trims are all over the place seems to make the camshaft theory unlikely.


I will be testing the spray patterns tomorrow and I'll post back with results and maybe a couple of pictures if I feel the need to post them.  I sprayed compressed carb cleaner through them last time, but my rig wasn't good so it was hard to watch the pattern while fumbling with power supply switched, holding wires to terminals, and operating the carb cleaner spray nozzle all at the same time.  From what I remember, The spray was cone shaped, but it was more of a spritz than a mist.  Also, I'm not sure how many psi the cans of carb cleaner produce, but this time I should have no leaks since I used the shrink tubing with an adhesive lining to go from the tiny straw, through growing fuel line sizes and finally to the size of the injector inlet.  This time my rig is much more user-friendly so I should have a free hand for pictures and slow mo video.  I'm also going to remove and check the basket filters before flushing them with carb cleaner again.  I may soak the tips for a few hours beforehand also.  Is there any harm in supplying the injectors with a constant 12v with no pulse?  Let's say maybe in 20 second intervals?  I will be shooting cold carb cleaner through them so I don't think heat would be an issue. I may end up using my old fuel pump to make a testing rail rig if nee be. Thanks everyone for all the suggestions.  So far you have been much more helpful than one of the Chevy forums I have wasted my time on typing huge posts with no answers.   I come on here and type a tiny bit and everyone jumps in to help and it's not even a car forum.

[McKay420]

Just found a tech service bulletin issued in 2016 for all GMs and oil mainenance.  Without proper care, oil sludge can become a huge issue, basically coating the entire oil pan/system in black sludge.  This directly causes problems with the camshaft lobes and lifters as Gregg suggested.  As for the  steam I feel coming from my exhaust, I'm starting to think I may have a very minor blown head gasket causing a coolant leak.  My coolant level is not dropping at a noticeable rate, however, but my exhaust is emitting a steamy white smoke.  It's thin kind of like a cloud on a sunny day and not gray and exhaust-y like it should be.  I'm thinking I may just disassemble the top end just to see what I'm dealing with and as a learning experience since the most I've done is remove the intake manifold and valve covers.  Starting to feel pretty confident though.  It's funny now how I thought cars were super complicated like 3 months ago and now I can talk circles around my town "mechanic" who doesn't understand fuel trims one bit.  He's like "I just do what my scan tool tells me".  Wft does that even mean?  He sees MAF circuit low and immediately replaces MAF?  That's what I got from that statement.  He's super old school and spouts off all these common myths/misconceptions, such as "downstream sensors affect fuel delivery just as much as upstreams".  That was one example and I've heard him say much worse.  I just can't remember what right now.  Oh yeah...it was "fuel pumps either work or they don't work".  I'm pretty sure it's very common to be able to squeeze a little more life out of a failing pump using a rubber mallet to tap the gas tank, but maybe that's the misconception 

[Gregg]

If you have variable valve timing, it may be oil pressure activated.  The reason the timing chain was mentioned is both noise and blips on the scope.  A camshaft isn’t unidirectional; the valve springs reacting against the lobes can give it counter rotational forces that may cause less than stable signals on a cam position sensor.  In other words, looseness in the timing chain can cause increasing rotational variations in the cam.  With as many miles on the vehicle as you stated, the timing chain cannot be in the best shape.   
Moisture in the exhaust may be normal combustion byproducts that collect in the exhaust system until it has a few highway miles and is fully warmed up.  Most likely you are seeing oil smoke due to the diluted oil going through the intake valve guides (and maybe the piston rings).  With so many miles, the valve stem seals are not doing a very good job and the intake manifold vacuum just sucks the oil in.  There are ways of changing the valve stem seals without removing the cylinder head.
You may want to go for slightly heavier weight oil and get rid of the seafoam before you put any real load on the engine.  Fram filters may not be the best choice; Wix or Delco are the best for the $ although Fram does make some premium ones that are OK.  Rock Auto is a good source of parts of all kinds but with shipping sometimes some things are cheaper locally.

[mikerj]

...and the fault is? The reason you suspect CKP is...? even the slightest bit of info?

I've had a CKP fault once - 90's Ford Fiesta, car would not turn over, CKP fault disables the car. Cleaned it and it was fixed forever until some scallies stole it and wrapped it around a lamp-post.

A faulty crank sensor can not stop the engine turning over (i.e. being cranked by the starter) unless it's physically fallen into the flywheel and jammed it.  It will prevent the engine running of course.

[McKay420]

If you have variable valve timing, it may be oil pressure activated.  The reason the timing chain was mentioned is both noise and blips on the scope.  A camshaft isn’t unidirectional; the valve springs reacting against the lobes can give it counter rotational forces that may cause less than stable signals on a cam position sensor.  In other words, looseness in the timing chain can cause increasing rotational variations in the cam.  With as many miles on the vehicle as you stated, the timing chain cannot be in the best shape.   
Moisture in the exhaust may be normal combustion byproducts that collect in the exhaust system until it has a few highway miles and is fully warmed up.  Most likely you are seeing oil smoke due to the diluted oil going through the intake valve guides (and maybe the piston rings).  With so many miles, the valve stem seals are not doing a very good job and the intake manifold vacuum just sucks the oil in.  There are ways of changing the valve stem seals without removing the cylinder head.
You may want to go for slightly heavier weight oil and get rid of the seafoam before you put any real load on the engine.  Fram filters may not be the best choice; Wix or Delco are the best for the $ although Fram does make some premium ones that are OK.  Rock Auto is a good source of parts of all kinds but with shipping sometimes some things are cheaper locally.

Valve seals makes sense since I just pulled my PCV hose and there it's full of oil, even after changing the valve cover gaskets and detail cleaning the valve covers and PCV valve and surrounding areas.  Well it's not really a PCV valve in this case, I would call it more of a PCV restrictor, since there isn't an actual valve, but just a hole.  Are you talking about using compressed air to keep the valves pushed up or isn't there another method where you just have to find TDC on each cylinder before you undo whatever holds the valves in?  Woudn't that be the nut/bolt in the middle of the rockers?  I guess I can probably figure that out on my own since I have an AllData subscription, but I don't think they have alternate methods for doing things like valve seals.  I may actually decide to just go with a complete rebuild this summer before I start buying too many individual pieces that would usually be included in a rebuild or I'm gonna end up wasting money.  A rebuild kit is only $450 which seems pretty reasonable.  Not sure if it comes with pistons though or if I even need them.  How many extra miles does a well done rebuild usually get you if somehow the body and suspension or other components don't wear out first?

A faulty crank sensor can not stop the engine turning over (i.e. being cranked by the starter) unless it's physically fallen into the flywheel and jammed it.  It will prevent the engine running of course.

Don't some vehicles disable the fuel pump in the abscence of an RPM signal?  In this case, it would crank, but not turn over for even a second.  I never had a no crank problem.  It was a crank, no-start.

[mikerj]

Don't some vehicles disable the fuel pump in the abscence of an RPM signal?  In this case, it would crank, but not turn over for even a second.  I never had a no crank problem.  It was a crank, no-start.

Cranking the engine is turning it over.

[McKay420]

Yeah I guess that makes a little more sense.  I always get that mixed up.  Ok so my engine would turn over, but it wouldn't fire.

[tautech]

You imply it's an injected motor and the fuel rail pressures required are such that an electric fuel pump is normally used.
Most vehicles they can be heard rattling away until required rail pressure is reached when the key is turned on.

In such a motor if all things that normally support combustion are OK it's either no ignition spark or no injector pulse that would stop an engine from firing. Or in the case of an ECU with various sensors either a crook ECU or faulty sensors.

[McKay420]

Well when my engine wasn't firing, I couldn't hear the fuel pump prime.  If I take a paperclip when this happens and jump from socket 87-30 where the fuel pump relay goes, the pump starts up no problem.  I have since replaced the fuel pump (for a bad check valve) and have not had this issue.  Today, however, I used the old pump to make an injector rail tester and noticed that the amperage was only around 1.5a.  When I measured the amperage of the same pump while it was in the vehicle (used multimeter to jump 87-30) and got 7-8 amps.  What is normal for a fuel pump?  It seemed to hold pressure fine today on my rig when it was running, but I think the most I saw it go to today was 2 amps.  Anyway, we're getting quite far off topic from my original question.  The no-start has not happened in a couple months.

I rigged a can of carb cleaner to each injector using fuel lines and shrink tubing to adapt the size.  I sprayed each for at least 20 seconds and at least half of them had a bad spray pattern and the other half were literally PERFECT.  So perfect I did not feel the need to take pictures or anything.  After being sprayed, the other half slowly opened up to I'd say 95% quality spray pattern.  I also flow tested them after that.  Specs for my injectors say 33lb/hr at 50psi (flex fuel).  This comes out to 41.6g every 10 seconds.  I wired a rocker switch to control the injector, with the fuel pump constantly running on the same power supply circuit.  Pressure held steady at 52 psi during testing.  Each injector was tested 3 times and an average was taken.  Here are the results: 39, 40, 38, 39.5, 40, 36, 41, 40.  As a percentage with all injectors added together, They are working at 95% efficiency, which should roughly account for 5% of the 15% fuel trims.  I also replaced the O-rings.  Before reinstalling, I dumped a can of Seafoam on the pump while it was running in order to fill each injector with Seafoam.  Let rail sit full of seafoam for 30 minutes and was slowly pulsed out of each injector.  As I write this, I have not started the vehicle yet.  Injectors were not kept in the same order as taken out.  I will report back if any of this helped anything, but that would be quite the shock.

[McKay420]

After cleaning the injectors, the idle problem is still there, but it runs perfectly for the first 10 minutes now, compared to 1 minute before the cleaning.  Also, the acceleration hesitation reduced by about 80%.  There is still a slight hesitation, which after messing with it tonight, I figure could be the accelerator position sensor.  At 300,000 miles, it's seems very likely that it could be the rest of the problem with the acceleration.  I can squeal my tires now whenever I want (more like a "squeak" and not a squeal), which wasn't possible before.  The irritating part of the night, though was after starting the vehicle after reinstalling the injectors, my cheap $30 wifi scanner completely went to s***.  If I can't send it back, I may have to dissect it and see if there are any burnt traces or components.  It looks like it's just getting no power at all and I've tried it in 2 other vehicles.  Definitely gonna drop at least $100 this time on a new one, but who knows how long that will be.  It's driving me nuts not being able to read my fuel trims and other data.

[Gregg]

I assume the fuel pump should draw 7 to 8 amps to pump 52psi to 8 injectors and would be quite surprised if the old pump can maintain the pressure drawing only 1.5 amps.
If the crankcase vent hose keeps filling with oil, the problem is more than valve stem seals; probably combustion products leaking past the rings.  It maybe the cylinder you found full of fuel, but coolant is the worst for making rings stick.  If you are losing coolant and can’t find where, it may be a head gasket problem. 
The best way I know to replace valve stem seals without taking off the heads is the compressed air through the sparkplug hole method. Don’t try to keep the engine at TDC with compressed air in the cylinder because if the air pressure should decide to rotate the crank while you have the valve spring off, it can cause the valve to fall in.  In other words, let the air pressure push the piston to BDC before taking off the valve spring keepers and make sure the cylinder doesn’t lose pressure.  A squirt of oil will help seal the rings.
Another relatively inexpensive diagnostic you may want is one of the USB otoscopes that you can look into the cylinders and see how scored they may be.
If you are considering rebuilding the engine and keeping the vehicle for another 200K miles or more, consider buying a brand new crate engine.