Cylinder 4 misfire
Dead misfire on #4. Did a clear flood and to me that sounded ok. No abnormal cadence. Both the intake and exhaust plugs were severely carbon fouled and the customer had us change the oil while it was here and we captured maybe a quart of oil. I put 2 new plugs in it and no change whatsoever. Misfire counts just kept climbing up. I did an in-cylinder cranking and running of #4 and #2 (known good) I am not proficient at all with analyzing the in-cylinder so I am making assumptions based on what I see. The #2 running has an area that looks different than #4 during the intake stroke. Can someone help me analyze this?
Try doing a regular compression test, with that little oil you could a bad ring
Wouldn't it have a noisy valve train? It is quiet
This example of 4.7 with a thrown exhaust rocker was quite when running. This this a 2 valve engine? If so you would definitely see no evo., and no ivo would pull a negative pressure . Here is a 4.7 with exhaust rocker arm spit . diag.net/file/f5qqi7z3f…
Thanks for sharing that failure i too am pretty new at using this type of method for diagnosis seen plenty of known good ones to see actual failures and what the failures are gives allot of learning experience for those of us new to this game. Thanks again.
Looking at the two seems like an exhaust valve is lacking definition even in the exhaust pocket. put an image of 2 superimposed on 4 slightly offset higher so you can see the difference. That being said, the only 1 litre left in the oil pan and the carbon fouled valves would lead me to looking at crankcase pressures .
I am working to get better at analyzing pressure patterns, I agree that evo is not very obvious. Here I tried to use reference wave form. Also some difference when the intake valve opens? I am learning so let me know.diag.net/file/f3ld9ezmt…
I would do a regular compression test on all cylinders for comparison purposes. 1 quart of oil is inadequate for any engine, especially that one. if all cylinders are with-in spec, I would lean toward a fuel injector issue. Also, I would be really surprised if that engine will ever function properly knowing that it only had 1 quart of oil upon arrival. I'm assuming you already swapped coil and…
I would start over with disabling the fuel, put 1 channel on COP 1, the WPS or a FLS on the dipstick tube using an old COP boot, in the intake, in the tailpipe, at WOT cranking, with sponges stuffed in the tailpipes. If the engine mechanical tests ok, scope the cyl 4 spark plug burn times and scope the injector volts and amps.
Ray does the sponge in the tail pipe increase the response of the pules sensor? I will have to try that.
Yes, stuff sponges into the tailpipes to pick up up good signals while cranking. I,ve found broken valve springs with that method.
Hello Ray. Is your cell number still the same as you mentioned in a post about 10 months ago where you were going to do a meetup up with some other Canadians??
Hi Caleb, my cell number is still the same but i don't recall any meetup.
Ok when I call it ,it just goes too voicemail or maybe you are busy lol. I would post it here again to make sure I have the correct one but not sure if you want me to do that.
Hi Caleb - sorry for this confusion. Please send me your cell phone number to my email so I can call you as well as re-enter your number (which has been blocked - hence it going to voicemail). … - that way we can connect 'in person'. Look forward to hearing from you.
Ray what does " in the intake, in the tailpipe, " mean? Can you re-write that maybe? I can't figure if you are using four sensors or doing mulit/different test. Thanks
To find any compression, valve, rocker, cam lobe, lifter issues quickly, first, disable the fuel system On one channel, connect to cyl 1 ignition. On another channel, connect the amp probe to measure the starter amp draw. The engine can have good compression, but still have valve/lifter, cam lobe issues. On another channel, connect the WPS500 or the FLS to the intake manifold and crank at…
Thanks Ray. Next time you do it, can you take a picture of "connect the WPS500 or the FLS into one of the tailpipes and stuff some sponges into the tailpipes" ? No rush, just some day. Thanks man!
Hi Geoff, I'll take some photos, but if you look at the Pico TA087 Exhaust Adapter for the WPS500, just put the adapter into a tailpipe and stuff some sponges into the tailpipes.
are the sponges instead of using the inflatable balloon thing? (can't recall the name) You're saying put the sponges AROUND the probe. I thought you had that inflatable thing, that's how/why I got so lost.
Hi Geoff, the sponges are stuffed around the probe only to force most of the cranking exhaust pulses into the probe.
Not trying to be a jerk but I dont see anywhere in your post were its says you verified spark?
Try a regular compression test and a cylinder leakage test. Maybe old school, but have found many a in cylinder problem that way.
Did you check fuel trims? Verify injector operation? Did you verify ignition? How many miles on the vehicle? How many miles since the last oil change? Since you have a scope why not perform a relative compression test? I'm really not a fan of "sounded" or "looked" okay. Too much room for error. Make measurements and provide actual results, not "in normal range" or similar. I feel you have…
Eric, sorry for the lack of info here. I rushed into making this post. I do have more info i'll share with later
The 4.7 engines are known to have the rocker arms fall out and the valve train is quiet when a rocker has fallen out, but will have a constant misfire in that cylinder. I’ve seen this multiple times, fairly quick to pop a valve cover to look.
Rocker or “Cam follower” since it’s an overhead cam, my terminology is old school
Doug, first time someone said "follower" I spent an hour looking for pictures to figure WTF they were talking about. :-)
Try a vacuum gauge on the intake also....
Sounds like a thrown rocker.These motors are known for this.Being that low of oil,I'm suprised that is all that is wrong with the truck.