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Any advice would be much appreciated! My brother's truck needs to pass CA smog as soon as possible and this one is now kicking my butt. Newbie here but i'm feeling good about the checks I've done. I also have access to a Snap On Solus Edge at the moment so I want to learn and knock this out efficiently. It has had a P0300 misfire issue for sometime probably close to 2 years, combined with a Service Traction control and Stabilitrak light that comes on and off. The last time it was smogged by a shop that did not solve the misfire and now it's that time again. I've just got back home to help him out a bit as much as I can.
Some symptoms:
-P0300 Miss on cylinder 3 mostly with half as many on 8 according to the data. Rough idle but runs fairly smooth and strong
-When the service stabilitrak light is on there's the rough 1-2 shift and clunky engagement when shifting into gears.
-At some point in the last year he had received the reduced power message while on the freeway
Here's a list of things recently done:
-New battery, old one tested bad
-Replaced battery ground cable (2016) due to wonky electric locks/ground issue
-Swapped coil 3+8 with non misfiring cylinders=No change
-Newer Iridium(.040) plugs + AC Delco wires which test fine. Also swapped after the coils=No change
-Cleaned MAF and reinstalled stock air intake. Had Airraid carb compliant intake. Still has oiled filter though..
-Verified MAP sensor voltages with vacuum applied
-Checked fuel pressure, 20-Key on 60-start up and 48-running
-Injector balance test showed all injectors almost exactly the same except for Injector 1? I will double check but I believe it was something like 4-5 psi off
-Ran some seafoam through the brake booster and techron fuel cleaner in the tank now
-Secured better the PCV hose that was broken/fixed
-Tightened loose driver side exhaust manifold
-Sprayed around intake looking for leaks=No change
One thing I am a little suspect of is the 02 B2S2 operation. I may not be understanding completely yet although I'm still studying up. B1S2 shows fluctuating voltage from 80-850 where as B2S2 was stuck in the 700s at that time. Truck is cold now so any verifications can easily be looked at. I can post anything off of this Solus Edge or videos that are needed.
I'd appreciate any help! Thanks for reading. I may have missed something but let me know, I'll verify right away!
Try a crankshaft variation relearn? How does engine vacuum look? Should be able to see that on the map sensor pid should be nice and smooth no fluctuations. How many misfires are in history? Does it run bad currently
Hey, I was hoping the relearn would do it but did not notice any change. Engine vacuum at idle was a fairly steady ahh 22 I believe. Should I throttle it as well? Didn't have a helper. I should have made a note of the reading but I it was right in the middle of a good spec so I called it okay.
It is running rough and missing on 3+8 mostly. Occasionally misses on a couple other cylinders but don't think those are as relevant.
Cheryl, it was a steady 19 at the intake manifold I noticed though on tapping the throttle it dropped to 10 or so before it jumped to 30. Exhaust restrictions?
ST Trim-1(%) -1
ST Trim-2(%) 0
LT Trim-1(%) 9
LT Trim-2(%) 11
Are you actually getting spark from cylinder 3 wire? Can it jump a gap in a spark tester. But one thing weird is you said ya have #1 injector flowing less fuel than the rest the firing order is 1-8-7-2-6-5-4-3 according to google. I’m wondering if the pcm is picking up the wrong cylinder misfiring since cylinder 1 is between 3 and 8 in the firing order. Maybe swap number 1 injector to cylinder 5 or something. Does the scanner perform a cylinder power balance test? To see if the misfire counter was right
I will double check that spark tomorrow but I'm fairly confident I'm getting spark to 3.
I'll definitely look into swapping an injector at this point. The scan too does have the power balance test. So my understanding is I should notice the drop and if not, that is the dead cylinder? Static compression is good but tomorrow I'll get running compression as well.
I'm almost also ready to pop the valve cover and confirm it's not a stuck lifter
EDIT: I better mention this sooner rather than later. I assumed it to be part of the crank variation wot portion that set it off. P2119 may be related to a misfire or no? It's a TPS issue correct?
Just make sure you don’t have a stuck closed exhaust valve. It’ll have higher compression than the rest of the cylinders. Also I can’t remember if the number 3 cylinder is one of the cylinders afm controls.
trims suggest a lean condition misfire as PCM is adding fuel. graph ST and LT fuel trims both banks on a fully warmed up engine and note the readings at idle again. Increase the RPM up to 2500 and note the trims as the RPM's increase. If they get better, you have a vacuum leak. By the misfire data, I think you have an intake manifold leak as you're getting a P0300 (random misfire) probably leaking more at the #3 intake runner.
downstream 02's report differently than upstream. they should be steady around the 700mv mark. B2S2 looks Ok... B1S2 should not be oscillating. that is the same side as piston #3. Fix the misfire first,
"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
I swapped injector 1 and the misfires didn't change. Still mostly on cylinder 3.
Sprayed water all along the intake gasket and no change. Seems with the symptoms this is the problem but I've tried brake clean and water. The engine doesn't fluctuate with that.
Rough idle can be caused by a vacuum leak, EGR valve open or a problem with the PCV valve. You have/had the problem with the PCV valve. Recheck for leaks and that you are using the correct valve. Unplug the EGR and see if the idle clears up although if the valve is open due to carbon deposits on the pintle you may have to remove and clean. All these will cause a lean condition and misfire.
I have concerns with the B2S2 02. Its reporting 200mv. It should be up around 700mv. The lean condition along with the 02 can and will cause damage to your CAT. Test the 02 with propane and see if it responds.
Just wondering, Is the EGR on the #1 bank side?
"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
It's my understanding this motor doesn't have an EGR valve. The PCV is internal to the valve cover. There was an updated cover due to the Active Fuel Management and oil consumption. Although this engine (220k) hasn't had significant oil consumption issues it seems there is a lot of oil/crud on the valve cover outlet where the pcv is housed.
How would I test the 02 with propane? Straight to the sensor with it removed?
I keep thinking and want it to be the common intake gasket leaking but I've checked with brake clean and water multiple times. No change in idle, still the same miss.
Did you ever solve this? My Silverado is having the exact same issue just on the other cylinder bank. 2 and 6 are the ones acting up and I have tried same tests as you.
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