timing chain issue?

Ask for and share advice on using the PicoScope kit to fix vehicles here.

timing chain issue?

Postby MD tech » Sun Nov 20, 2016 2:40 pm

Hey everyone, I have a 2000 olds silhouette right now that is misfiring under load, it is also setting a p0336 crank sensor fault. I ran a cam/crank correlation test with a pico 4425, both readings were at the sensors, both sensors are hall-effect, the crank is 24x, the cam is 1x. I am not seeing any dropout in cam or crank signals, however I set a trigger on the rising edge of the cam. I am seeing the cam randomly jump one crank window forward, to me it looks like a stretched timing chain, but I was wondering if it is possible for the trigger setting to cause this? I could not get the full waveform to upload, but I was able to get two screenshots. the first one is the most common, the second is where it jumps ahead. I have counted the crank pulses and it is only moving one pulse. I also do not see any significant change in crank frequency when this occurs, do I don't think it is the reluctor wheel moving. I appreciate any input that you have on this.
Attachments
wave 2.png
wave 1.png
Last edited by MD tech on Mon Nov 21, 2016 12:30 am, edited 2 times in total.
MD tech
Newbie
 
Posts: 7
Joined: Sun Oct 30, 2016 12:24 pm

Re: timing chain issue?

Postby STC » Sun Nov 20, 2016 3:16 pm

MD

Not enough information in your 2 attachments to make any judgement, other than the trigger, they are identical. Shame you cannot get the waveform to upload, that would have been much more useful, perhaps try again. What is the size of your PS Data file ?

I am not seeing any dropout in cam or crank signals,

Not 100% Gospel, but a signal dropping out would be more likely to throw a P0335 or P0340 DTC. P0336 suggests that the signal is there but it does not like it, which ties up very nicely with
cam randomly jump one crank window forward


I have counted the crank pulses and it is only moving one pulse.

Unless it has got VVT then it should not be moving at all.

Based on what you have written then a Stretched Chain, Tensioner Issue, Reluctor wheel moving cannot be ruled out.
Last edited by STC on Sun Nov 20, 2016 7:53 pm, edited 1 time in total.
User avatar
STC
Zen Master
Zen Master
 
Posts: 369
Joined: Sun Sep 13, 2015 2:10 am

Re: timing chain issue?

Postby MD tech » Sun Nov 20, 2016 6:14 pm

Thanks for the reply, the web page is telling me that the file is too large to upload. is there any way to cut frames out of these files, or do I need to re-take the recording?
MD tech
Newbie
 
Posts: 7
Joined: Sun Oct 30, 2016 12:24 pm

Re: timing chain issue?

Postby PicoKev » Sun Nov 20, 2016 8:45 pm

MD tech wrote: is there any way to cut frames out of these files, or do I need to re-take the recording?


Just open the file and hit "File / Save as / Save/" and you will see the standard save screen that you see every time you save a waveform. There is a large box in the bottom left hand corner that gives you the option to save "All waveforms / Current waveform only / Or specific Waveform numbers.

Choose exactly what you want to save and give it a different file name and hit save.

Check you file size is within the forum limit and post it.
Attachments
WF_Save.png
Last edited by PicoKev on Sun Nov 20, 2016 8:54 pm, edited 1 time in total.
PicoKev
User
User
 
Posts: 39
Joined: Thu Apr 05, 2012 9:16 am

Re: timing chain issue?

Postby MD tech » Mon Nov 21, 2016 12:24 am

ok, thanks. here is the waveform. See frame 5 for the jump.
Attachments
Oldsmobile_Silhouette_2000_Petrol_20161120-0001.psdata
(5.93 MiB) Downloaded 21 times
MD tech
Newbie
 
Posts: 7
Joined: Sun Oct 30, 2016 12:24 pm

Re: timing chain issue?

Postby STC » Mon Nov 21, 2016 1:07 am

I can see it jump on Frame 5 but that is nothing conclusive. You will need a fixed point to measure /compare from, for example the missing tooth on the Crank.

You will need to retake that capture with more time across the screen so that 6 -8 crank revolutions (a few more if you wish) can be seen across each screen. Maybe add another channel for O2S1 then try to catch it as it misfires.
Last edited by STC on Mon Nov 21, 2016 9:03 pm, edited 1 time in total.
User avatar
STC
Zen Master
Zen Master
 
Posts: 369
Joined: Sun Sep 13, 2015 2:10 am

Re: timing chain issue?

Postby Autonerdz » Mon Nov 21, 2016 4:46 pm

Nothing shifted. The scope just triggered on that ignition spike in frame 5.
User avatar
Autonerdz
Zen Master
Zen Master
 
Posts: 272
Joined: Wed Nov 20, 2002 4:19 pm
Location: Washington State USA

Re: timing chain issue?

Postby STC » Mon Nov 21, 2016 5:45 pm

Good Catch Tom, I did wonder what was going on there with the trigger, it appeared to trigger off nothing in that frame. Now I see the filter had hidden it.

Thanks :D
User avatar
STC
Zen Master
Zen Master
 
Posts: 369
Joined: Sun Sep 13, 2015 2:10 am

Re: timing chain issue?

Postby Autonerdz » Mon Nov 21, 2016 6:03 pm

I see the filter had hidden it.


I opened it with the latest beta. There was no filter applied. Files saved with filter may or may not open with it applied depending on the PicoScope build you are using to open it.

Not an issue as filter can be applied or removed in a saved file at will.

TIP: Never run live with filter applied..
User avatar
Autonerdz
Zen Master
Zen Master
 
Posts: 272
Joined: Wed Nov 20, 2002 4:19 pm
Location: Washington State USA

Re: timing chain issue?

Postby STC » Mon Nov 21, 2016 6:37 pm

I opened it with this version
PicoScope® 6 - PC Oscilloscope software version: 6.12.4.2427


It opened, with Zoom & Filters applied, as you say, not an issue - especially now that I am aware.

Thanks for the Tip. Makes sense.
User avatar
STC
Zen Master
Zen Master
 
Posts: 369
Joined: Sun Sep 13, 2015 2:10 am

Next

Return to Diagnostic discussion

Who is online

Users browsing this forum: No registered users and 2 guests