Sorry it all took a bit longer to get the files organised, but here we go, a few captures to consider and pick apart, with my initial thoughts, some of which might or might not be input from STC, who may or may not agree with the statements here, as while we agreed on lots, we did have some minor differences of opinion
, but without his input and help, we'd still be a big step behind, so once again thanks, but I'll take full responsibility for any daft statements (so all opinions of stupidity are mine alone
) and I will only share any praise ... Channel A = Battery voltage at battery Channel B = Amp Clamp 2000amps on battery cableChannel C = Amp clamp 20amps on Injector 2 (last capture only)Test A
First capture was fully charged battery, first crank for 24hours, while the battery is not correct for the car, it should cope fine as it's 600CCA.
The cranking shows at least 300amps to rotate, with compression peaks over 750amps on 2 cylinders, and over 400 on the other 2.
a. More AMPS than I would consider as correct ... but I'm no diesel expert
b. the time taken to rotate past the worst cylinder increases with cranking, could that be a build up (fluid in cylinders?)
Ok, so these thoughts are in hindsight to the further tests, but not too different to those expressed at the time...
rotations, well we are at a full 720° in 900ms so about 120-140rpm cranking
Key side notes:
- initial crank was instant, no delay. All the other tests had a delay between key to +50 and starter motor activation
- Seems to be attempting to start ... but that's hard to say for sureTest B
Next we added a charger as the 2-3 tests already done were taking their toll
Changes: disabled the fuel pressure sensors (both) at the fuel rail.
a. Still needs over 300amps not during compression, compression element still 2+2 split 400+amps and 600+amps, about 50% extra for 2, aprox.
b. The speed has increased to about 200rpm cranking
c. each cylinder is closer to equal time to rotate, unlike the clear difference in capture A above
d. same partern of 2 cylinders being worse then another 2
Key side notes:
- delay between key to +50 and starter motor activation
- still Seems to be attempting to start ...Test C
This is will the addition of injector 2 amp clamp to ID cylinders. Battery pack and charger now in use to sustain testing, sorry second battery pack, killed one already! Serious Amps being drawn.
a. Rotation speed during cranking is now aprox 260-270
b. Confirmed same 2 cylinders always with the higher amps (lots of captures, not just this file)
c. Harder to keep cranking going for any length of time, stops and tries again itself, but less continuous time each attempt.
d. Still 300amps for "good" 2 to reach compression, bad two can be anything from 400-700 amps, no real pattern as to why that fluctuates so much.
High amps identified on cylinders 1 and 3, see belowTest D
Final capture, for now ...
Change: injectors all removed so we can see if this is down to some mechnical issue or a compression issue.
a. rotates after initial inrush at about 192amps, much higher than our petrol engine, which would be at that level with plugs etc intact!
b. no longer a discernable 2 vs 2 issue, all 4 cylinders appear balanced in terms of requirement
b.1. would this rule the crank out? I think so ...
b.2. would this rule cams out? ... I think not entirely, but maybe? It's hard to guess here, but, if the cams (lobes or sprocket) had rotated so that the valves where opening or closing at the same point as another cam (allowing double compression when all things sealed), then surely you'd see some indication of this in the amps, for the force needed to open the now imbalanced cam lobes?
OK, so there is 8-10 amps variation, but not sure how much work is needed to understand this verse valve timing events, and then trying to map against potential unknown valve train failure posiblilities ? Would need to get an ID from crank or cam sensor, as injector removed
confession, so we are not entirely sure that the cylinders are free from fluid (water, oil, diesel), so this will need to be confirmed, and might be pivotal. watch this space.
Anyone have further analysis of captures they can add ... Please shout ... all files uploaded, so play to your hearts content ... I will edit channel file data to make them more suer friendly, well for any that finally go into the waveform library once we're finished...
Excess compression of 2 cylinders - what can cause this?
a. smaller compression area
b. part of the compression area filled with substance with less compressible properties (ie not fuel/air gas mixture)
Excess force to rotate engine
a. valve train issue (lobes/sprocket) -
aa.double compression on 1 cycle, normal compression on other cycle of 2 stroke.
b. crankcase issues
c. oil starvation in key parts, affecting 2 cylinders - a stretch I know!
d. external interference - aux belt, gearbox/torque converter?
what don't we think it is:
- aux belt based loads but will slip off belt if things look this way
Possible secondary issues, once initial thinks resolved
- fuel pressure
- fuel injectors (leaking fluid ?)
- glow plugs
Next test ideas ... feel free to chime in
1. Is the near 200amps to rotate the engine good? Full volt drop test, should have already done it, but with 600+amps the volt drop would be so high as to mask any cable issues, 200amps is manageable to understand cable performance.
1a probably try to get crank cam waveform while we are there
2. if we can recode (if they are coded) move the injectors, to see if the issue follows them ...
2.a Repeat with top lambda removed, see if we can hear or see anything different
3. Do a real compression test, to see if the lower amps cylinders are good, or low, so we can chase the correct 2, post test 2, so we know that outcome first, as key to know if a simple component move changes the cylinders involved.
4. We could endoscope the inlet to see what's going on?
Otherwise, I think it's cam cover off to see the cams and inlet side of things first hand ...
Ok, will reply to other posts tomorrow