2009 Jeep 3.7 Need help with these patterns FIXED

Hello gents. If anyone would be so kind as to check out these waveforms and give me your input I would appreciate it. 2009 Grand Cherokee 3.7 no start. Vehicle was at dealer who told customer "engine is shot." Customer was not satisfied and brought it to us. I found plugs to be soaked with fuel. Especially bank 2. checked for injectors leaking or stuck on with no problems found. Performed cam crank sync and cannot find a known good pattern. Then checked in cylinder compression on cyl. 1 and Primary ignition on cyl 1 to see if it is out of time. Any input would be appreciated.

Well I can't add the files for some reason so I guess disregard the post.

You should be able to put the files in a folder then compress it to a zip or rar
It then should attach to a post

EDIT
rar doesn't work needs to be zip

Tried just now and no good.

try again

comp and ignition

Strange, ill try to attach a file just to test

EDIT
crossed posts, I see you've got it working now
Good info here on in cylinder pressure and ignition sync

Yea I have watched this many times, but it seems to be of little use on this application...

Sorry 'bout your troubles with uploading, sir. Tracked down a known good waveform, and yours looks in time.



The fouled plugs on bank two, is that the bank that's monitored by the CMP? 'Cause it's possible you could have skipped timing on the other bank and not know it on the waveform. But, you'd think it'd at least start and run badly.

Clearly the engine is making compression, at least on bank one... Can you get a cursor on the lowest part of the decompression stroke? I'm not seeing much vacuum there, but I could be looking at it wrong.

Tyler wrote: Sorry 'bout your troubles with uploading, sir. Tracked down a known good waveform, and yours looks in time.
Clearly the engine is making compression, at least on bank one... Can you get a cursor on the lowest part of the decompression stroke? I'm not seeing much vacuum there, but I could be looking at it wrong.

I'm glad you brought that up. I was thinking the same but, really don't anything about these in cylinder captures.
I've been reading along in your thread too trying to learn as you guys go.

Tyler, is there any chance you might let me send you the pico file? I have it saved to my pc and really would like someone with more skill to analyze it for me.
To answer your question, yes the cam sensor is on the right bank which is the one with no compression. I checked each cylinder and it is 0 on bank 2. Bank one I am around 145 across the board.
Cranking vacuum at intake was tough to read on a gauge. It went to about 2 but hard fluctuations.

JoesAutoElectric wrote: Tyler, is there any chance you might let me send you the pico file? I have it saved to my pc and really would like someone with more skill to analyze it for me.

No problem! wrenchturnsyou@gmail.com

Be warned - I'm not amazing with in-cylinder stuff, still learning.

To answer your question, yes the cam sensor is on the right bank which is the one with no compression. I checked each cylinder and it is 0 on bank 2. Bank one I am around 145 across the board.
Cranking vacuum at intake was tough to read on a gauge. It went to about 2 but hard fluctuations.

Oooh, so bank two is flatlined? :ohmy: But the cam/crank says it's in time... Did this thing get overheated?

Trying to think of anything else that would cause one bank to go dead besides timing. :blink:

This is another thing. the same bank upon arrival at the shop was completely flooded with fuel. Pulled plugs blew cylinders out and checked oil for contamination. It is minimal surprisingly. Anyway, I saw the low compression in the relative waveform. I then blew out the cylinders and retested. I saw that it had humps across the board now and installed an in cylinder transducer on cylinder 2. It was a strange pattern which looked nothing like the one on cylinder 1. It was low at about 40-45psi and looked strange in its form. Almost triangular and leaning a bit from the rising edge. I wanted to see if the thing would at least make an attempt to start however, so at this point I installed new plugs and tried to get it to start. It backfired through the intake like a bomb went off. When I pulled the plugs out again they were wet again after just one attempt to start it. At this point I checked compression again and bank 2 is completely flat..this is with the transducer and also a gauge to verify. So..now I dry it up again and make one last attempt to start it before quitting for the night. I should have quit while I was ahead. The intake blew off the freaking truck on the second try. I am disgusted with this thing to no end. 8 hours with no answers yet.

Reading through this it can only be a mechanical failure, so there is little point in trying to diagnose further, there comes a point when you have to start stripping the covers off to find out what is going on.

Andy, you are right. This morning I pulled the plugs back out and got #2 cylinder on tdc. I performed a leak down test and confirmed 100% leakage through intake valves. No reason to go any further at this point as the customer opted to replace the engine. What have I learned from this? Well...unfortunately not much...other than stop beating a dead horse. I knew compression was an issue and pressed on thinking I would find something instead of simply doing a basic test. I know better...Thanks for the input guys. I'd still like to know more about the in cylinder capture I have on the good cylinder...but I have a lot to learn in that department.

Hey Joe! Got your e-mail, thanks sir.

First thing I saw was the ignition timing, 7 degrees BTDC? Seems a bit too far advanced for a cranking engine. That known good waveform I found showed almost no advance at idle. :huh: Also, LOVE the Pico software for in-cylinder waveforms. Soooooo easy to take measurements.

I thought the decompression pocket looked weird, what kind of transducer did you use here? I ask because it looks like the trace flatlined as the cylinder was going into a vacuum. Almost like the vacuum was outside the transducers range.

Speaking of, it also seems like the transducer didn't zero quite right? It looks like 'zero' ended up at around 1.5 PSI. Nitpicking, I know. I just notice this because my Fluke PV-350 has to be zeroed manually.

Thank you!
Yes about 7 degress. Which I was told is normal by my techline. They say that cranking it may do that in the strategy. Yet another thing I was not sure about and still am not. I would need a known good engine to try the test on I suppose.
I used the PV350 as well Tyler. I tried for 20 minutes to get it zeroed and yet had no luck. That was the absolute best I could do. I have 4 different probes which I set in the pico software. I used the pressure probe to do this test, though I am not sure this is correct either. I have no formal training for this setup and can't see to get a straight answer on what to use and when. I will email you the probes I have and you can maybe give me an idea of what I did wrong so I can not do it again.

JoesAutoElectric wrote: Thank you!
Yes about 7 degress. Which I was told is normal by my techline. They say that cranking it may do that in the strategy. Yet another thing I was not sure about and still am not. I would need a known good engine to try the test on I suppose.

Interesting... Wonder what the reason for that would be. :huh: I'm not arguing with the techline, just curious. Honestly, I don't add an ignition trace to my in-cylinder captures as often as I should, so that's kinda on me for not having a better idea of 'normal'.

I used the PV350 as well Tyler. I tried for 20 minutes to get it zeroed and yet had no luck. That was the absolute best I could do. I have 4 different probes which I set in the pico software. I used the pressure probe to do this test, though I am not sure this is correct either. I have no formal training for this setup and can't see to get a straight answer on what to use and when. I will email you the probes I have and you can maybe give me an idea of what I did wrong so I can not do it again.

Cool, I'll keep an eye out! I'm really glad you mentioned the zeroing problem, 'cause I've had the same trouble at times. :lol: Usually, I can get a perfect zero if I use the dial. Occasionally, though, it'll get skewed, and I can't get all the way to zero with the dial maxed out.

Anyway, I don't think that's anything you were doing wrong.

Well, again, I appreciate you taking the time to help me out. I do hope you can give me some insight on the pressure pocket you referred to as well. I am trying my butt off to learn this stuff and not in a position to bite the bullet on the WPS at the moment.

Email Sent.