14 Chrysler Tc Misfire At Idle

Richard Owner/Technician Buffalo, New York Posted   Latest   Edited  
Question
Driveability
2014 Chrysler Town & Country Touring 3.6L (G ERB Flex) 6-spd (62TE)—2C4RC1BG3ER455064
Has Misfire On Cyl # 2 At Idle

first time posting not sure how to do this. van came with a miss on #2 cyl did relative compression and it showed #2 weak, i removed intake and check compression, it is lower than the other ones. removed front valve cover and found cam lobe worn on exhaust cam. i replaced cam and rocker arm, reassembled still have miss on 2 at idle, still have low compression. i made two sensor to check pulse on intake and exhaust. trying to learn how to read these waveform. maybe some could help to see what is going on with these engine, I'm pretty sure it is a bad valve but would like to know what the waveform is telling me. thanks for amy help

rich …

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Hophy Diagnostician
Shanghai, China
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Hi Scruggs, it is nice captured waveform. From the waveform of the intake pulse. The #5 cylinder pull lower than normal. it is caused by the #2 cylinder has leaka… condition. it is also refleelcby low current at #2 cylinder compression. So i assume there is still have something leak in the #2 cylinder. you can try the crankcase pulse to verify whether piston ring have fault. And you can let…

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Stephen Technician
Gallatin, Tennessee
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From what I see on your screenshot; cyl 2 has low compression(current draw), The exhaust pulse for 5 has a raised hump on it, compared to the others, which I could attribute to 2 leaking out the exhaust on compression. But, 5 also has a short intake pull and 3 draws much more current than 1,4,5&6. I haven’t thought of how those would be related, if they are. I want to run the Pico file to…

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JJ Technician
Quincy, Massachusetts
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5's intake pull and the increased amperage on 3 can be explained by the crankshaft speeding up on 2's compression stroke due to the loss of compression. When 3 comes up on compression the crankshaft tries to travel at that same speed but meets much higher resistance due to the good compression in cylinder 3 which slows it down and also causes the starter to draw more amperage to overcome that…

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Stephen Technician
Gallatin, Tennessee
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The posted .psd file is not the same as the one that the screen capture is from. Mainly the intake waveform is very erratic, not smooth like the screen capture. It shows the intake differently. The base line current draw of the starter is 120A. The current rise of the normal cylinders is 74A The current rise of cyl 2 is 32A. The current rise of cyl 3 is 110A!!! At the peak of #3 starter current…

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Richard Owner/Technician
Buffalo, New York
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good catch Steve i have uploaded the right file (14 tc take 9

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JJ Technician
Quincy, Massachusetts
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Here is a good video on the subject from Super Mario Diagnostics and Brandon Steckler youtube​.​com/watch?v=smSdJG… We can measure how long each cylinder takes to come up on compression. If we look at the time of the cylinders that appear similar, they're each around 45ms to go from baseline to peak amperage. I would think with the right math you could figure out the cranking rpm…

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Richard Owner/Technician
Buffalo, New York
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Use the second file (14 tc take 9) I see what you mean about the speed increases because of the low compression. You must have a picoscope, if you put your cursor on the base and the other one on the peak in the lower right of the screen it tells the rpms of the engine. I see clt takes 47 ms and cranks ar 1250 rpms, cly 2 takes 35 ms cranks at 1750 rpms cyl 3 takes 95 ms and cranks ar 650 rpms…

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JJ Technician
Quincy, Massachusetts
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Right on. I was thinking that would have an effect on the intake pulse because of the way pulse sensors work. They don't really measure pressure, they measure changes in pressure. If you took the piezo element out of it and connected a scope to the wires on it then pushed on it with your finger you would see voltage on the scope. But if you held the same amount of pressure on it with your…

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Mike Technician
Atlanta, Georgia
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Is it just me or is there a problem with ads. YouTube stopped at 1:20 in for a 2 minute ad, then about 10 minutes later, stopped for a 13 minute ad. Do I need to subscribe to something to watch without that level of disruption?

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JJ Technician
Quincy, Massachusetts
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I felt like I got the same thing watching that video. I skipped around the video a couple times and it honestly felt like I was getting an ad every 5 minutes or so.

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
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Hi Mike: I can't say it is just you though I didn't see any ads. No, I'm not subscribed to anything on YouTube. I do use Firefox and some Extensions (Privacy Badger, AdBlock Plus, uBlock Origin, Clear URLs, Browser Safety) which work rather well for that sort of thing. Why so many? Some urls won't display properly when certain Extensions are used. For example, I watch the 4-6:30pm local news in…

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Mike Technician
Atlanta, Georgia
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Thanks Guido. I'm browsing with Opera on a Windows laptop. Maybe it has something to do with the video being linked here because when I went to YouTube and watched it there, no ads.

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Richard Owner/Technician
Buffalo, New York
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Good explanation jc. I hope some of the other guys read it thank for the help ,rich s I put my sensor on the dipstick tube and waveform looks uniform, rings must be good.

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Richard Owner/Technician
Buffalo, New York
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Three draws more current because #2 slowed and it takes more current to get three up to speed which is the next cyl in the firing order

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Richard Technician
Stony Brook, New York
Richard Default
 

Nice job on the waveform. It seems to show #2 loss of compression and low vacuum pull on #2. I would expect to see a valve not sealing when the head comes off. You could try a leak down test to confirm it before pulling it off. But at this point, I would be confident that something is wrong on #2 based on the waveform provided. My guess is the exhaust valve on 2 is not sealing, which wouldn't…

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Stephen Technician
Gallatin, Tennessee
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The intake waveform is very different in the 2 psd files. What changed?

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Richard Owner/Technician
Buffalo, New York
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The first form is taken with the pedal to the floor, clear flood mode to keep engine from starting, the second one I pulled the fp fuse and left the throttle closed. Think the second is a better results of what is going on. thanks rich

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Stephen Technician
Gallatin, Tennessee
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That’s interesting. The first waveform, though “noisy”, actually showed more detail of what was happening. That makes sense because the accumulator effect of the intake manifold would be eliminated by the WOT. Mac Vandenbrink (DiTeK?)had a pulse sensor in development that was to to used in the duct in front of the throttle plate, for better detail. I don’t know if it was marketed.

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Richard Owner/Technician
Buffalo, New York
Richard Resolution
 

thank you guys for the input on my waveforms, I finally got the head back from machine shop today, they found both exhaust valves on #2 cyl bad. one was pitted the other one cracked. I am posting the cracked one if you are interested. Misfire is gone now, thanks again for the help Rich …

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