When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I"M BUSTED!!! YOU CAUGHT ME! Yes, that was the 12V hot stud, I screwed up and will need to redo all those readings on the coil. When I popped the bonnet yesterday for more investigating, I immediately recognized my goof. I was in a hurry, sun setting to my back, working in shadows, and camera flash reflecting up camera screen was creating problems ,as flash insisted on popping up. Without thinking, I thought that was a shock tower stud. I was focused on the pins order, wire color codes, a cell phone camera and cell phone oscilloscope at the time.
The one thing I did discover yesterday is the coil's iron frame is not part of the grounding. It is insulated from the coil and ignition module. I wondered if they were counting on the hypernik (or whatever alloy) frame as a means to dump current in conjunction with the wiring harness, but that is not the case. Rust and aluminum corrosion would not be a factor. One more question mark put to bed.
Your questions on the wiring harness are valid and that YG (now SLG, Slate Light Green) cluster is very suspicious. I'd hope the original harness was around to retry that short segment, no luck. One of the other questions I have is whether the '99 harness is a new one from the dealer or a used one from a bone yard. It'd be quite a challenge to generate a test harness considering the coils need their unique plugs, but three wires with stick pins could be jammed into the plug terminals #2 and temporarily pierce the SLG wire beyond the splice.
I"M BUSTED!!! YOU CAUGHT ME! Yes, that was the 12V hot stud, I screwed up and will need to redo all those readings on the coil. When I popped the bonnet yesterday for more investigating, I immediately recognized my goof. I was in a hurry, sun setting to my back, working in shadows, and camera flash reflecting up camera screen was creating problems ,as flash insisted on popping up. Without thinking, I thought that was a shock tower stud. I was focused on the pins order, wire color codes, a cell phone camera and cell phone oscilloscope at the time.
The one thing I did discover yesterday is the coil's iron frame is not part of the grounding. It is insulated from the coil and ignition module. I wondered if they were counting on the hypernik (or whatever alloy) frame as a means to dump current in conjunction with the wiring harness, but that is not the case. Rust and aluminum corrosion would not be a factor. One more question mark put to bed.
Your questions on the wiring harness are valid and that YG (now SLG, Slate Light Green) cluster is very suspicious. I'd hope the original harness was around to retry that short segment, no luck. One of the other questions I have is whether the '99 harness is a new one from the dealer or a used one from a bone yard. It'd be quite a challenge to generate a test harness considering the coils need their unique plugs, but three wires with stick pins could be jammed into the plug terminals #2 and temporarily pierce the SLG wire beyond the splice.
Maaaaan,,, let me start a WHOLE new thread on the "FUNNY" things I have done on this 4, 5yr learning curve in working on these cars... I've got you beat!, hands down...
There is a thread up on the XK x100 forum right now... A guy who was getting all kinds gear box fault codes because of a dirty fuse. These cars are going to be getting twisted more and more for reasons like this,,, I would guess.
IMHO,,, Jaguar made these cars WAAAAY to much leaning in the direction of sensitivity to electrical signals. I think it's going to be the downfall of the XK x100 as age really takes it's toll... Rigorous and methodical cleaning and,,,, way more than my Fred Flintstone mind can handle,,,, may be the only way to avert this...
Dude. I am envious of your abilities... You made me start shopping for 50$ hand held oscilloscopes...
Oscilloscope images revision 1 You can ignore the first set of images above, since my mistaking the +12V stud for a ground superimposed a 1 volt feed to the readings instead of ground and threw them off.
These are displays of coil pin #2 at idle. Since that pin shares the common Slate Light Green wire with 3 other coils, I have to believe it is showing 4 coils through 2 engine revolutions over and over again. The second image shows the sequence starts with positive spike and is quickly followed by a negative volt signal (not just grounded, a negative value) IF the primary voltage met the 2-4 amp levels indicating successful fire. (It is likely the ECM would return 4 engine misfires if the ECM plug was disconnected from that one wire and we couldn't trick it into thinking they're all good).The negative signal is followed by some transient voltage rebounds, ringing, as the signals decay exponentially. I happen to notice the 120 hz reading and figure it is evaluating all ripples to come up with that high of a number. Interesting that the software has established the bias voltage for measurement and averages the peak spike at +6.08V and the negative signal at -4.32V. I got my homework to do to take better advantage of this apparatus, I've just scratched the surface.
Other displays will be forthcoming, including some of the VVT solenoid which I'm having issues with. But for now, I have to get back to work on my Honey's '50 MG TD and '58 ****** CJ5.
ECM Trigger pulses from ECM to coil pin #3, This pulse is isolate to one coil only.
I wish conditions were better for taking pictures- in order to block out glaring reflections from backlights, I need to close the bonnet down on top of me while the fan is blasting very hot air in my face.
This image is from the VVT solenoid, same on both banks, engine idling with codes cleared. The PWM, Pulse Width Modulated signal looks to be nearly full ON, almost no OFF dwell.. This P1396 error is a persistent irritation and the last error issue for this Jag, other than a scratchy rear speaker.. Garage receipt shows mechanic pulled bank B rocker cover to find cam tensioners had been replaced but commented small chain is noisy and seemed loose. Did not have the savvy to examine the small chain tensioner. He cut off the plugs and attached new ones which make no improvement. Since I removed the coil cover, I guess it is time to dive into the heads to examine/replace the small chain tensioners.
With the scope hooked up to the solenoid, I placed the cell phone on the windshield and revved the engine and did not see any variation in the waveform. Maybe the ECM expects a load before advancing intake cam.
My oscilloscope leads are made from a cell phone ear buds/mike combo and are not long enough to reach into the cabin where I can drive and view responses. I can make some extensions but there's another improvement I have yet to play with. I "bought" a cheap bluetooth earphone on Amazon for less that $5, but it took so many months to get here from China, Amazon gave me a refund before it finally arrived. I can attach probe leads to the bluetooth adapter microphone and then have a wireless oscilloscope. That's on the TODO list..... someday..
You guys have posted some amazing theories and info. It's so much appreciated. Unfortunately, right now, I'm in a bit of a nightmare situation. We have 4 cars. My wife's Audi A6 with 210,000 miles is running great. My Mercedes SLK has just died with a camshaft correlation error. It's had this problem for about a year and was running great. Two days ago that ended with a load knock coming from the camshaft. It's in my garage with the XK8 not usable. We also have a 2007 Audi Q7 which wouldn't start 3 days ago. There is some fuel issue with that one. Right now we are down to one car so my priority is getting the Q7 running. It may be an engine out job for the SLK. When it rains, it pours.
^^ Sorry to hear that, especially in your Florida summer heat and humidity. Absolutely no fun working on vehicles when you are sweating so much you cannot even see due to the sweat pouring into your eyes. I got soaking wet with sweat this morning just adding a little air to one set of tires....
With the scope hooked up to the solenoid, I placed the cell phone on the windshield and revved the engine and did not see any variation in the waveform. Maybe the ECM expects a load before advancing intake cam.
Default action of ECM for a P1396 is to set the VVT solenoid drive duty cycle to 0 (intake camshaft fully retarded), so I wouldn't expect a change when the engine is revved.
Best to start a new thread for the issue so this one doesn't go OT.
^^ Sorry to hear that, especially in your Florida summer heat and humidity. Absolutely no fun working on vehicles when you are sweating so much you cannot even see due to the sweat pouring into your eyes. I got soaking wet with sweat this morning just adding a little air to one set of tires....
Unfortunately, the SUV was parked outside and won't start so I have to do the diagnostics and work out there in the Serengeti, only more humid
Like a bad coin, I'm back. I'm bringing this thread back to life as I have just gotten some time to work on the Jag. Just to let you know why I've been gone this long. My Audi Q7 died. I tried all that I could but it ended at the junk yard. My SLK had new used engine installed. That took me more time than I though it would. That car runs great now. Right after I got the SLK running, we were hit by hurricane Ian here on the west coast of Florida. I had some damage to my house, but my fathers house was severely damaged. My house is all repaired and I'm working on my fathers place.
So yesterday I decided to take the cam covers off because I keep thinking that this engine problem seems like a timing issue. I rotated the engine to line up the cam flats. This is what I saw.
Great to find that little problem, joking of course, good to know where to go from here.
More than all that, glad you all are OK and the houses are and can be repaired, some were not.
Our thoughts are with you on both accounts and thanks from letting us know "the rest of the story".
Hi and welcome back!
Good to hear you're getting back to some sort of normality.
There is a degree of misalignment, but I think that's more likely to throw a P1396 rather than any P035x codes. Obviously address it whilst you have the cover off, but I still think your problem is elsewhere.
I'll re-read the entire thread since much of it will have leaked out of my head by now. As someone on here put it: "My memory is as good as it ever was - just not as long"...
Great to find that little problem, joking of course, good to know where to go from here.
More than all that, glad you all are OK and the houses are and can be repaired, some were not.
Our thoughts are with you on both accounts and thanks from letting us know "the rest of the story".
Hi and welcome back!
Good to hear you're getting back to some sort of normality.
There is a degree of misalignment, but I think that's more likely to throw a P1396 rather than any P035x codes. Obviously address it whilst you have the cover off, but I still think your problem is elsewhere.
I'll re-read the entire thread since much of it will have leaked out of my head by now. As someone on here put it: "My memory is as good as it ever was - just not as long"...
Unfortunately, I don't know how to fix the camshaft issue. I also have a memory that is not long
I doubt the cams are a toooth off, just the intake cams aren't isn't fully retarded. Get some channel locks and grip each intake cam on the rough casting and rock it a touch and see that it settles down with the flats lined up.
^^
My guess is that the VVT on that bank wasn't quite fully retarded when the secondaries were replaced, so the relationship between that inlet cam & the rest of the valve timing is slightly askew. The cam has now settled in the 'fully retarded' position - valve spring pressure on cam lobes?
A few have reported similar issues (although usually with attendant P1384/P1396 codes) after a tensioner change.
IMO it's not sufficiently off-time to upset the motor unduly (it's not complaining), but best addressed.
Q.E.D.
07-01-2022, 10:19 AM
