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2014 Town & Country
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Discussion Starter #21
...Remember that this is an Atkinson cycle engine, so TDC will seem like it has an intake leak. You'll have to go a few degrees beyond TDC to ensure the intake valves are closed.
Yeah....I had no idea - completely oblivious to there being Atkinson style engines and all of that. Thanks for volunteering that info. My ignorance definitely would’ve made for problematic leak down results wouldn’t it?! Thanks again...you’re a good man!!

This is not an engine I would recommend to a first-timer for head jobs. It's a full day or two for an experienced mechanic. Given it's not your primary car though, if you did do it, don't freak out if it takes you a whole week. Take your time and double check everything. You have a lot of parts that can be easily misaligned if you rush through it.
It’s my wife’s primary driver but we have four cars for three drivers and she usually stays within a small radius of home. It wouldn’t be much of an inconvenience until something goes wrong with one of the other two!! :)

Assuming it turns out the head will need removed and I decide to take it on myself, I won’t do it as a time sensitive project. I won’t dive into it until after we’ve replaced her primary driver.

Thanks again guys!! I really appreciate you helping out and talking me through this stuff!
 

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It would be difficult to run the 3.6L Pentastar without the exhaust manifold since it is integrated in the cylinder head.
Correct, but my point was, engine sucks cold air were it is supposed to only blow hot exhaust gases.

Without catalytic converter in this case. :)

Good catch. (y)
 

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2013 Dodge Grand Caravan
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Yeah....I had no idea - completely oblivious to there being Atkinson style engines and all of that. Thanks for volunteering that info. My ignorance definitely would’ve made for problematic leak down results wouldn’t it?!
Good chance I might have been wrong, at least in terms of static cam position. See this post and my reply.

But it shouldn't make any difference going past TDC on a leakdown test, since at the point Atkinson cycle valves would close, Otto cycle valves will have already been closed and both cycles would open at the same point beyond that.
 

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2014 Town & Country
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Discussion Starter #24
@Sienile No worries at all - but it’s very kind and thoughtful of you to think of me and my situation!!

Like I said, I learned a lot from your original post to me. I was unaware there were “Atkinson” style engines - causing me to look up what it was and learning there were also “Otto” style engines....learning the difference, pro’s & con’s of both.

That’s what makes a great forum like this - people willing to help and share while also being willing to concede when they don’t know or may have been mistaken.

All is well!! Thanks a bunch!

By the way, I’m gathering the tools I need to do the compression & leakdown tests.

I’m hopeful they will arrive by Friday so I can take off the manifold and have everything ready to go Saturday morning.

I think I still need to order a 1 1/16” socket for the crank pulley nut. I’m concerned my Schader valve removal tool won’t arrive by Friday, causing me to delay working on it in the evenings next week or even two weekends from now.
 

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I wouldn't worry too much about having to turn the crank by hand or removing the Schrader valve. The compression test is likely going to tell you all you'll need to know.
 

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Discussion Starter #26 (Edited)
OK...you guys have been great with helping diagnose my rough idle, P0303 misfire issue on my 2014 Town & Country with 168k miles. I was able to do compression and leak down tests today. Please give me your thoughts / conclusions of the results:



My thoughts with respect to the compression tests....although Cylinders 3 & 5 are a little off kilter, they're still within ~5% of the mean of the other four cylinders. That shouldn't be cause for concern - correct?

With respect to the Leak Down test - the results seem solid. They're so solid, I'm not convinced I'm doing the test properly - but I have no idea what I could be doing incorrectly. I've studied tons of YouTube videos on leak down tests along with the 3-4 videos for how to use my tester (OTC 5609).

Thoughts??

A summary of what I've done so far to troubleshoot the rough idle / P0303 misfire issue.
  • Confirmed lots of misfires on Cylinder #3 with my Autel scanner.
  • Smoke tested the air intake system. No vacuum leaks identified. I did this before the van started throwing P0303 codes.
  • Swapped the #1 & #3 coils. The misfires stayed with Cylinder #3.
  • Swapped the #1 & #3 plugs. The misfires stayed with Cylinder #3. I noticed a little bit of oil on both the #1 and #3 plug electrode. The oil went up 3-4 threads on plug #3 and a couple on plug #1.
  • Checked for a valve cover gasket leak around Cylinders #1, 3, and 5. It looks clean with no leaks.
  • I don't know how to test if the computer is sending a good signal to the coil to create spark. However, I connected a Lisle 20610 in-line spark tester to both the #3 (the cylinder throwing the misfire code) & #1 plugs. Both were showing a lot of spark and looked the same for both cylinders.
I've not done much with testing fuel delivery to Cylinder #3 - primarily because I can't figure out how to unclip the freakin' fuel injectors LOL!!

I truly expected the compression and leak down tests to indicate terrible things were associated with Cylinder #3. Any ideas??

Thanks!!

Edit: Added a chart with the compression & leak down test results to make it more readable
 

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2013 Dodge Grand Caravan
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With results like those, I'd suspect fuel as well.

There's a small black tab below the red lock tab. Once you pull the red tab up you should be able to press the black tab and lift it off.

If swapping the injector doesn't work, you have a bad wire on either the coil or injector.
 

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One question. For your compression test, did you have the intake removed for all the compression tests? I imagine 1,3, & 5 could be checked with the intake on. Did all your cylinder(s) reach their peak pressure with a similar number of pulses on the gage. For example 1, 2, 3 and 4 took 4 pulses, but 5 took 7 pulses. I find it interesting that your two lowest readings are cylinder 3 and 5 which are in the back of the engine compartment and sit next to each other. Other than these questions, your results look good.

Sounds like it is time to remove fuel injectors.
 

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Discussion Starter #29
One question. For your compression test, did you have the intake removed for all the compression tests? I imagine 1,3, & 5 could be checked with the intake on.
Yes. I did the compression tests with the intake off, spark plugs out of all six cylinders, and with light blue Scott shop towels loosely packed into the plug wells and air intake ports.

Did all your cylinder(s) reach their peak pressure with a similar number of pulses on the gage. For example 1, 2, 3 and 4 took 4 pulses, but 5 took 7 pulses.
Yes, same number of pulses. I did the compression test using 6 pulses - turning off the ignition just as the 6th pulse began for each cylinder.

I’ve been considering re-doing all of the tests...what’s it going to hurt? I’m especially unnerved by the leak down test results. It seems to smell of an inadequate testing process.

...I find it interesting that your two lowest readings are cylinder 3 and 5 which are in the back of the engine compartment and sit next to each other. .....
I’m with you! After considering the compression test results, I expected the leak down test to suggest a head gasket leak between 3 and 5.

I about fell onto the garage floor when the leak down test showed Cylinder 3 had zero leakage!

....Sounds like it is time to remove fuel injectors.
Yeah...I’m going to have to figure out those dang clips!

Other than simple maintenance, I’ve only been working on cars for a couple years. Any unsolicited advice isn’t just welcomed but encouraged!

A couple years ago I bought a new car to play with, do some modding etc...

Shortly after putting a couple oil catch cans on it, I was telling a friend that I thought the hardest part of the install was figuring out how to undo all of the clips!!

Another one of my projects is to make a trip to the junkyard ‘cause I busted an ABS clip on my daily driver (2007 Ford Focus) while changing out the front wheel bearing....what’s the common denominator — more clips for me to struggle with!!

Thanks for your continued help and sharing your thoughts...you guys are great!!
 

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Sounds like you did a good test! My only thought is the shop towels in the intake ports. Now I understand you do not want any debris to fall into the intake ports. But a cranking compression test is supposed to be done at wide open throttle (WOT). So it is possible the shop towels could have a mild effect. Still, your test results says the motor is solid inside.

BTW, did you run the leak down test at TDC? Just wondering for my own knowledge.
 

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Discussion Starter #31
....My only thought is the shop towels in the intake ports. Now I understand you do not want any debris to fall into the intake ports. But a cranking compression test is supposed to be done at wide open throttle (WOT). So it is possible the shop towels could have a mild effect. ...
That’s a good thought! I’ll do the compression test(s) again without any towels in the air intake ports.

BTW, did you run the leak down test at TDC? Just wondering for my own knowledge.
Yep...all cylinders were at TDC. A guy on YouTube showed how he uses a ballon to ensure TDC.

My son laid on the floor, turning the crank bolt clockwise as I watched the ballon fill up and then shrink as the piston began leaving TDC.

After seeing the balloon shrink a tad, I’d have my son turn the crank clockwise a touch to get the piston back to TDC. I would then connect the leak test gauge to the provided test kit tube that was screwed down into the spark plug threads.
 

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A trick we used to use when I suspected a fuel issue causing a misfire is run the engine at idle off of a different fuel source being drawn into the intake not the injectors. I used propane.
If the engine runs smooth you know you're looking in the right place.
You can buy one:
https://www.oreillyauto.com/detail/b/otc-4538/tools---equipment-16488/mechanics-tools-16816/fuel-system-tools-17342/5c1a4886fcc8/otc-propane-enrichment-kit/7148/4606854

Or make one out of an old propane torch kit: Not my pic but my setup looks very similar.
58215
 

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2013 Dodge Grand Caravan
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A trick we used to use when I suspected a fuel issue causing a misfire is run the engine at idle off of a different fuel source being drawn into the intake not the injectors. I used propane.
If the engine runs smooth you know you're looking in the right place.
You can buy one:
...
Or make one out of an old propane torch kit: Not my pic but my setup looks very similar.
Solid advice, but be careful with that. Only turn it on right before cranking and turn it off immediately after shutdown. And have a fire extinguisher handy. One backfire can really screw your whole day up.

Heard of a guy doing that and leaving it on for a few minutes before cranking. Ripped his intake in half back in the days of metal intakes. :p
 

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I'm having the same issue with a 2015 t&c, P0303. Mine was intermittent so I think its electrical not a burned valve. I replaced the #3 injector with no improvement- should have swapped injectors between 2 cylinders to troubleshoot instead of replacing. Had to break the red clip and pick the pieces out of the connector to get it off. I want to check continuity to the pcm from the injector plug but cant find the pinout and location for the pcm. Mine is either going to be a bad harness or pcm I think at this point.
 

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Discussion Starter #36
From you guys' guidance, I was able to figure out the clips on the fuel injectors. I swapped the fuel injector on the misfiring cylinder (#3) with the cylinder #1 injector....the misfire did not follow the fuel injector.

This is what I know or have done to figure out the misfire's root cause:
  • Spark plugs (NGK Laser Iridium) are one year old, gapped at .043, torqued to 13 ft lbs, and have ~12,000 miles on them. They were replaced ~6 months prior to my noticing a rough idle that eventually threw a P0303 a couple weeks after first feeling the rough idle. The van runs great when being driven. The rough idle and the P0303 misfire code are the only indicators it's having a problem.
  • Smoke tested the air intake system but didn't find any indication of a vacuum leak. I performed the smoke test after first feeling the rough idle but prior to the van throwing a P0303 cylinder misfire code.
  • Swapped the #1 & #3 plugs....misfire stayed with cylinder #3.
  • Swapped the #1 & #3 coils....misfire stayed with cylinder #3.
  • Checked the spark on cylinders #1 & #3 with a Lisle 20610 in-line spark tester. Both cylinders were showing a lot of spark and looked the same inside the tool's spark observation chamber.
  • I interpreted the plug and coil swaps, in addition to what info. I gleaned from the Lisle spark tester, the van is getting good spark. So I thought it could be a burnt valve, bad compression or something similar with the engine internals.
  • Performed both a compression and leak down test. The results didn't point toward engine internals being the likely culprit of the misfires. See Post #26 above for the test results. With seemingly good spark and internals, that led me to it likely being either a fuel or air issue.
  • I swapped the #1 & #3 injectors. The misfire stayed with cylinder #3 with the scanner detecting no misfires on cylinder #1 after the injector swap. This leads me to believe the injectors are spraying as intended.
  • After swapping injectors, using my OBDII scanner, I confirmed the scanner is also seeing misfires on cylinder #3. The scanner didn't see misfires on any of the other cylinders after about a 10 minutes idle.
I'm trying to figure out if my scanner can check air to fuel ratio's so I can determine if my current air to fuel ratio is within spec -- even though I currently don't know what the air to fuel ratio specs are for this van. I've read that 14.7 to 1 is the optimal air to fuel ratio?? I assume if the computer (is it the ECU?) isn't sending the correct amount of fuel to the #3 injector, it would mess up the air to fuel ratio and the air to fuel ratio would be greater than 14.7 to 1??

Assuming the injectors are spraying as they should, how do I test to see if the computer (is it the ECU?) is sending the correct amount of fuel to the #3 injector?

FYI....my OBDII scanner indicated the idle was between ~600-800 while it was idling for 10 minutes after swapping the injectors.

Thanks again for all of your very valuable and helpful assistance thus far!! Any unsolicited thoughts are encouraged if you think I'm barking up the wrong tree in trying to troubleshoot this misfire problem.
 

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2009 Dodge Grand Caravan SXT 4.0
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It sounds like you've covered all of the basics and done your diagnostics. Yes, 14.7:1 is the stoichiometric air/fuel ratio (for gasoline), so that's what the computer shoots for using O2 sensor readings to adjust the short-term and long-term fuel trims. The computer (aka ECU or ECM) doesn't adjust each injector's pulse width (amount of fuel) compared to other injectors, just to lean/richen the air/fuel ratio. See what the fuel trims are on your scanner, they might be abbreviated STFT and LTFT, possibly with a 1 or 2 at the end to indicate each bank. However, that will only tell you how each bank is doing, so if the bank that #3 cylinder is on is different than the other bank, that might help.

Since this sounds like a mechanical problem, maybe pull the valve cover to see if the valvetrain looks OK. The next step would be pulling the cylinder head and having it checked out.
 

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Yep, given that it stays in that cylinder with all spark and fuel bits swapped, it's either wiring or valves. Slap a noid on the injector connector and check the coil by cranking it over with the plug visible and grounded so you can check for spark. If those check out fine, it's in the valvetrain. You previous tests ruled out major cylinder or piston damage.
 

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Discussion Starter #39 (Edited)
Yep, given that it stays in that cylinder with all spark and fuel bits swapped, it's either wiring or valves. Slap a noid on the injector connector and check the coil by cranking it over with the plug visible and grounded so you can check for spark. If those check out fine, it's in the valvetrain. You previous tests ruled out major cylinder or piston damage.
I did a noid test today. The bad injector (#3) is getting pulses from the ECM. It's pulsing intensity looked the same as Injector #1. I recorded 20 second videos of my noid tests for both Injectors #1 (good) and #3 (the injector on the cylinder getting the P0303 code).

Injector #1 video
Injector #3 video

After the test, I used a mechanic's stethoscope to see if I could hear any weirdness near Cylinder #3. Cylinder #3 is definitely noisy when compared to the other five cylinders.

Unless I'm overlooking something, the P0303 doesn't seem to be spark, compression, or fuel system related. Have I overlooked something?? What else does that leave that could be generating the misfire?? Rockers?? Cam?? Anything else??

Questions to help me better understand root cause of this P0303 misfire code....
  • Based on what I heard with the stethoscope this afternoon, it seems like the misfires are being caused by the rockers, lifters, or cam. Is there anything else inside the valve cover that could be causing the misfires?
  • Are there any tests I can do on the rockers, lifters, and cam to pinpoint if any (which) of those things are the cause?
  • Would air related problems cause misfires? How would I test that?
Thanks Guys....you've been a HUGE help with this!!

This is what I know and have done to figure out the misfire's root cause:
  1. Spark plugs (NGK Laser Iridium) are one year old, gapped at .043, torqued to 13 ft lbs, and have ~12,000 miles on them. They were replaced ~6 months prior to my noticing a rough idle that eventually threw a P0303 a couple weeks after first feeling a rough idle. The van runs great when being driven. The rough idle and the P0303 misfire code are the only indicators it's having a problem.
  2. Smoke tested the air intake system but didn't find any indication of a vacuum leak. I performed the smoke test after first feeling the rough idle but prior to the van throwing the P0303 cylinder misfire code.
  3. Swapped the #1 & #3 plugs....misfire stayed with cylinder #3.
  4. Swapped the #1 & #3 coils....misfire stayed with cylinder #3.
  5. Checked the spark on cylinders #1 & #3 with a Lisle 20610 in-line spark tester. Both cylinders were showing a lot of spark and looked the same inside the tool's spark observation chamber.
  6. I interpreted the plug and coil swaps, in addition to the information I gleaned from the Lisle spark tester, that the van is getting good spark. I thought it could be a burnt valve, bad compression or something similar with the engine internals.
  7. Performed both a compression and leak down test. The results didn't point toward engine internals being the likely culprit of the misfires. See Post #26 above for the test results. With seemingly good spark and internals, that led me to it likely being either a fuel or air issue.
  8. I swapped the #1 & #3 injectors. The misfire code stayed with cylinder #3. My OBD2 scanner didn't detect misfires on cylinder #1 after the injector swap. This info. leads me to believe the injectors are spraying as intended.
  9. After swapping injectors, using my OBD2 scanner, I confirmed the scanner is seeing lots of misfires on cylinder #3. The scanner didn't see misfires on any of the other cylinders during a 10 minutes idle session.
  10. I noid tested Injectors #1 and #3. Injector #3 is getting pulse signals from the ECM. It looks similar in intensity to the pulses being received by Injector #1.
  11. Using a mechanic's stethoscope to listen through both valve covers, the area around Cylinder #3 is definitely noisier than any of the other five cylinders.
 
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