Yeah these look good. Triggers,voltages and inversion fixed. IDK what's normal for 1995 or if the current variation is real (or significant).

Back then the issue was

Are these waveforms from when it was running "really rough"? I would get waveforms from really rough and really smooth and compare. That should allow figuring out normal vs abnormal if we can't find values for 95.

I'll try to make a montage that will (should)(might?) generate good ignition waveforms (if it ever stops raining). I've got coil packs instead of a distributor and use the current clamp but will see what shakes out.

And again, with the ignition waveforms, compare smooth and rough.

Meanwhile, check the CKS and CPS:

 

Ok I stand corrected, the 95 was in fact a different PCM. I know the drivers in the 96 and 97 and I think up, were much smaller

 

The waveforms were zeroed with the CH1 and CH2 markers/traces before I hooked up the probes. After I hook up the probes they'll jump up away from the marker. Sometimes they'll jump back down and line up automatically. When this would happen for the current it would drastically affect the maximum value displayed. That's one reason I don't think the current values are correct/accurate. However, when this would happen on the voltage waveform, it wouldn't change the maximum value displayed (I think that's why they're all so consistent compared to the current).

I agree with you. I'm not sure if the height of the voltage spike has much relevance. It looks like all of the injectors are grounding and opening properly. How do you get 4volts/division? My attenuator is a 20:1, so wouldn't 20V/divison X 1/20 = 1V/division? I don't really understand how the attenuation setting on the scope works.

 

All of these screenshots were taken at idle. The idle is still a little bit rough. I did try holding the throttle at 1000+rpm where it was the roughest, but I couldn't notice any difference in the waveforms, and there wasn't any change in the maximum values displayed.

 

Im not sure I have it right either. I do know if you have a 20:1 attenuator, it says x20 on it (maybe), so you take your volts/division setting, x number of divisions, and multiply by 20 to get to where your actual volts are. Where I got screwed up was telling where the divisions are. I believe they should be the hash marks on the vertical axis. Usually like a centimeter or so.

Any idea why the current display reading is so different between 1,3, 5 and 2, 4, 6?

 

I'm almost positive the current readings are wrong because I saw it change when the waveform jumped away from the reference marker. I'll have to try those again and see if I can get them more consistent.

 

The purpose of attenuation is to protect the box from damaging voltage. It reduces voltage by a factor (for the Hantek attentuator by a factor of 20:1-- if the voltage is 20V, a 1.0V is sent into the box). This is reconciled by choosing the 20:1 selection in the vertical menu where the voltage is multiplied by 20 to end up with the correct measurement.

Interestingly, on Injector 6 although you selected a current clamp factor (which also has an attenuator) the end result is probably OK.

What are the vertical settings for Channel 2? I think you have to know that before you can try to figure out the discrepancy.

 

So what does each tick mark on the vertical axis represent? 4V? So each square (5 tick marks) equals 20V?



I had the same settings for channel 1 and channel 2 the entire time. On the screenshot for #6 I had changed to channel 2 just to record what settings I had. So for the channel 1 waveform the vertical is 20V and for channel 2 the vertical is 200mA on all of them.

 

Correct.

OK great. It appears that regardless of the voltage the ramps and pintle movements look OK. IDK why there's such a discrepancy in the voltages, try fiddling with the CC. Regardless, IIWY I'd go to CPS and CPK next and make sure they're synced.

 

So, I installed the new header pipes. Ya'll were right, no change. The engine bay is noticeably quieter though lol

Here's my cam and crank sensors. Pretty sure they're identical to Dave's.




It does seem like the Jeep is idling a little lower now. Like 500 or less rpm. Maybe something related to the new header. The idle is definitely rough, but it still shakes the most right above 1k.

97Grand you mentioned lifter preload. That would only come from worn cam/lifter/pushrod right? Not allowing the valves to fully open? What would be other symptoms other than rough running engine? I'm not very familiar with that so I'd have to do some research. I haven't really been thinking it's a mechanical issue because my compression is so good. I don't hear any ticking/knocking coming from the valvetrain.

 

Well I was just brainstorming. How about your fuel trims, what are they? Can you post them? Just an ordinary scan tool. O2 sensor new and stock?
Lifter preload, well, possibly yes. I have a whole nother post on that from when I did it. No it's not just from worn parts, it can come from parts being changed such as head gasket not being the same thickness as OE, (somebody used the thicker, 'seals all' felpro) that will do it every time, you can use thicker gaskets but must adjust preload with shims or difft length pushrods. Mopar knows how critical preload is and at the factory I think they check each one and they used different length pushrods to adjust, which were sometimes marked with a colored band, if those have been altered from their original spots it will alter it, ...best thing to do is check.
I'll try to dig up the link, There is also a method to use which counts the turns of the cap screw after you get to zero lash, if memory serves it's 3/4 of a turn. Then you torque to spec.
One sure sign of them not being right is a lifter that isn't pumping.
This is a critical setting and the tolerance is less than the width of a US dime.

 

What does a vacuum gauge say? Does it dip when it misfires? How about a cylinder balance test? Just disconnect the injectors one at a time and record the drop in idle speed.

 

I did do a valve job on it a little over a year ago (burnt exhaust valve on #1). I had the valve job and everything on the head done by a machine shop, but I reassembled it myself. I believe I did use a felpro gasket set but I made sure to reassemble every part back in their original positions. That was about 10k miles ago and the jeep has ran great until recently. I'll have to look and see if I can find what gasket set I ordered.

I don't have a OBD scanner or vacuum gauge so I'll have to find some before I can do those other checks.

 

The gasket set I used was Fel-Pro HS 9076 PT-2 Cylinder Head

 

rock auto only says thickness is 0435" - .0534". Which is wrong, it has to be one or the other. It LOOKS like the OE one so you're probably ok , oe being 0435" .
Pull the valve cover and see if they're all oiling.
The guy has an oscilloscope but no scan tool which is $20 on ebay