Sorry for the sloppy photos of the scan. This time it was just me trying to pause the reading so I could capture the wave. Idk why it does not keep the recording for longer.
Plugs look like so:

 

Wow, they're really dry. SURE there is fuel? What compression #s did you get?

 

Signing off for "Valentine's Day" stuff.

You better, too.

 

Compression test: 5 cranking cycles, battery upset. All plugs out and throttle plate wide open.
6<95
5<70
4<90
3>80
2<70
1-80
The OEM tester was spinning at the connector piece between the hose that connects to the threaded portion. Im not so sure its supposed to do that.

 

Correct, the fuel pump relay is out, 49psi confirmed at the rail before pulling the relay. I read not to keep dumping fuel into the cylinders while crank testing, not to flood the engine, as this would mimic a no start.

 

The cam sensor does show and artifact on that example. https://www.cherokeeforum.com/f2/99-...8/#post3562024 ,Apparently that can be from the ignition coil firing. I do like the option on this video: , to also probe the ground, but with my jeep not running, I'm curious if this would ever show in the short blips I can capture.

 

Absolutely. Baseline wouldn't be 0.0 volts.

Hit refresh button:

CPS and CKS are fine and in sync.
The blips are ignition artifact (which we considered the last time this happened).
We can try to confirm/isolate ignition scatter by disconnecting coil, plugs, fuel injectors, etc. but why chase a red herring.
Compression is REALLY bad but needs to be confirmed. You absolutely need to do a leak-down test then get ready to make MAJOR decisions.
My point about the dry plugs is that I don't think it's a spark problem. If it were the plugs would be soaked from all the cranking before you pulled the relay.
Start testing the injectors. I'm pretty sure you can use the Hantek with the 10x probes. IIRC the voltage is ~35V (although I did see some 60s, I forgot why that was)(which is why I'm only "pretty" sure).



But our poster CHGreen01 was getting less:



If you do this you should also measure current simultaneously.

Or just get noid lights. IMO the injectors aren't shooting at all and we don't need to get flashy.

 

I think you should pick up the HT-201 attenuator to increase the ability of your unit. They're cheap:


Got Prime?

 

To be clear the fuel pump relay has been out for a good while now, enough time I would have thought fuel would disappear by now, wouldn't it? I'll at least put thr relay back in an crank one more time.
Ill look into the scope attenuation add ons, I did find some feature I the help tab, iirc 35v might be the max on the scope? I'm not sure I read that right.
If spark isn't the problem, I should still see some with a screwdrive arcing to the valve cover or such, right? That was not witnessed.
I also dont know about the validity of the compression numbers and the tester. I kind of think that's worth doing agai, with a new tool. Would you agree?

 

Right:

But again I got a 60V peak, and although your 10x probe should cover it, don't blame me if the unit gets smoked.

Mandatory. If those are real you got MAJOR decisions to make. Do the leak-down test it'll help find the issue if those are real.

 

No need to guess. Test.

IMO those plugs look like they spark regardless how many times the engine was turned over with the relay out.

 

Cause we can't be simultaneously saying

"Oh look there's ignition scatter, but there's no ignition".

 

I see you posted in this thread before:

https://www.cherokeeforum.com/f30/st...-4-0-a-226299/

If you get it to start, yeah, we gotta do that.

 

Did you ever do anything with that sloppy timing chain?

 

That is fair if we do have spark. I'll need a spark testor or such to confirm. Perhaps I can ohm the ignition coil tonight after work.

The chain stayed as it seemed in spec, as best as I could measure it from a straight edge.
The plugs weren't wet, all I know is before pulling the relay, I could smell fuel every time I tried cranking. I'll see if I can check for Wet plugs and return the relay to confirm this.