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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
Alright so I had some time to mess around with the Hantek again today. I've added some videos and screen shots to that google drive for ya'll to look at. I didn't do the ignition vs current test because I don't have a fuse buddy that size and also I couldn't fit my current clamp down in there next to the coil. I guess I could have pulled the conduit open and put it on the wire coming out of the PDC though. Anyway, I had ordered another HT25 a few days ago and it came in so I was able to put one on the distributor lead wire and the other on a spark plug wire. The scope trigger worked pretty good on the distributor lead but I still am having a lot of trouble getting any kind of readable waveforms from any of the spark plug wires. There's a video in the drive of the two together.
Good news is I was able to test the injector voltage and current signals with no problems. Trigger worked fine for those. I put screen shots of each injector in the folder. They all look pretty identical except for the #4 current which looks like its considerably lower than the other 5.
The injector waveforms are upside down for some reason. IDK why I couldn't figure out how to switch it (other than on the current clamp just physically changing the orientation). https://drive.google.com/drive/folde...nf?usp=sharing
Although it's set to read a + inflection it's actually reading a - deflection, and at a point that's different from where you have the trigger actually set. Quite the stumper!
Did you install the software from the disc that came with the Hantek or download the latest version from the website?
Try changing the Trigger Slope to - and see what happens.
Can you increase Time to 5 or 10ms to get more waveforms in?
This morning I had a few minutes to mess around with it again. I uninstalled all the drivers and software I had and then reinstalled them from the Hantek website. I was using version 1.0.10 but now I have 1.0.30. It looks a little different. I'm working on a Surface Go tablet so I don't have a disc drive and neither does my wifes laptop.
I tried the ignition setup again and Dave you're right the trigger is working opposite of what it should. I forgot to try switching the slope to negative before I unhooked it. Anyway I took two more videos of the distributor lead vs the 1 cylinder plug wire zoomed in and zoomed out with the trigger on the negative side. I feel like these are the best results I've gotten so far. The only thing is it still lags and freezes so much that I can't see any clear changes in the waveforms. You can see in the top left corner of the screen it says "wait" when it's frozen and then "trig" when it's working. I tried doing a throttle snap while zoomed in (not in the video I uploaded) but it just doesn't respond quick enough to see anything. Does yours do this or is it smooth? I might try it on the wifes laptop next.
No it's not hard at all. Just install a new PCM and poof! done.
Obviously you disregarded posts #41 and 42.
And what's up with that link that doesn't work.
I disregarded posts #41 and 42 because I have successfully replaced an injector driver in the PCM before, and obviously they have not. If you know how to solder then you can fix this problem for a few dollars. If you want to spend $200 for a refurbished PCM or $40 for a junkyard PCM (and you are lucky enough to find the exact model you need at the junkyard), then by all means go for it. I fixed the link, here it is again: https://www.cherokeeforum.com/f2/how...m-95-a-248325/
Does sound like an injector driver issue, but good luck taking a PCM apart, I tried it, not worth it. You will ruin it, trust me. Better off replacing it, or locate one so you know you can go buy it.
The problem is that the components are sealed with a goo that defies all solvents and can't even be removed mechanically.. I did some extensive research, and the only chemicals that will remove that stuff are horribly toxic and very expensive.
Yep. I watched some youtubes and the guy was claiming he was removing it with acetone, so I went for some acetone, and it didn't even touch it. By the time you scrub it with a brush or something you have wiped out hundreds of microscopic laser printed resistors and caps. Just ridiculous.
This is simply not true, at least not for a '95 XJ. The PCM components are covered by soft rubber. I used a razor blade to easily remove the top layer and then a brush to gently clean off the remaining rubber. I de-soldered the bad injector driver, soldered on a new one, and filled in the missing rubber with silicone. The injector driver was not microscopic and wasn't hard to solder on using a regular soldering iron.
Engine: 4.0, new lifters valve job with new springs and exhaust valves, preload set with shims
Originally Posted by wcjeeper
This is simply not true, at least not for a '95 XJ. The PCM components are covered by soft rubber. I used a razor blade to easily remove the top layer and then a brush to gently clean off the remaining rubber. I de-soldered the bad injector driver, soldered on a new one, and filled in the missing rubber with silicone. The injector driver was not microscopic and wasn't hard to solder on using a regular soldering iron.
Could be the 95 is OBD1 and the 96 got more complex with the OBDII. However I got my 97 PCM Cardone rebuilt for under $100 picked it up 30 mins after I ordered it and had it installed by lunch. Gave me credit for my mangled core too. Plus it fixed a shifting issue that I had no idea it would.
10-04-2019, 09:41 PM
