relative compression test

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relative compression test

Postby tangoman » Sun Oct 09, 2016 3:36 am

Hi just like to know if any one knows when I do a relative compression test and use the WPS 500 its always tell me the compression is low but it ok I did one just today on a 2.2 lite Toyota Camry and set up the software and told it was a 2.2 and 9,5 to one compression but it still come up and tell me it low ?
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Re: relative compression test

Postby PicoPhil » Mon Oct 10, 2016 2:37 pm

Good afternoon
Please could you tell me which version of software you are using in PD and which Window operating software you have installed on the PC. I can then tests this software. I am sorry that you have experienced this problem.
Kind regards
Philip
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Re: relative compression test

Postby tangoman » Tue Oct 11, 2016 2:39 am

Hi I using software version 1.8.4.1692 and windows 10

Thanks for you help
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Re: relative compression test

Postby tangoman » Tue Oct 18, 2016 9:24 am

Hi Picophil
just see if you came up with anything with the software and why it tells me the compression is low

thanks
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Re: relative compression test

Postby FioranoCars » Thu Oct 20, 2016 7:43 pm

Hi Tangoman
Might be worth checking these settings:
comp test settings for Pressure.png
Settings


Especially sensor volume!

Also from a generic perspective the hose you are using to interface the Pressure Transducer to the spark plug is critical, if not Pico's then suggest you try theirs (the volume of the inside of the hose and it being incredibly resitive to expansion under the cranking cycle), if theirs, then maybe Phil can comment on possible defective units or wear and tear requiring a replacement? Of course it being air tight and done up well is key too :D

Hope that provokes some thoughts, and please let me know what it was, as sadly otherwise I'll be posting the same thing one day myself!

Cheers
Richard
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Re: relative compression test

Postby tangoman » Fri Oct 21, 2016 11:48 am

Thanks for the info I have play around with the sensor volume . made it worst ! I am using the WPS 500 with the hose that came in the box !
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Re: relative compression test

Postby FioranoCars » Fri Oct 21, 2016 12:21 pm

For my money, and of course Pico will know best, but if the software is "good" then the issue is either
1. a parameter - in this case the volume is key, plus engine size and compression
2. The hose and WPS seals each end
3. The hose
4. The probe location/connection (this is unlikely to be the fault on several tests on different cars!

You have consistent results, just low, hence the hose and value for volume seem most likely. Sorry but you best check the manual for the volume figures as I'm not near my kit.

If changing the volume made it worse, then changing the other way will make it better! (if you decreased the volume it would make it worse, if you increased it, it should compensate more and make it better!!)

Have a play, and let us know what the number was in the volume field

Best
Richard
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Re: relative compression test

Postby FioranoCars » Sat Oct 22, 2016 3:44 pm

Hi
This might also be a potential issue, if you have serviced, or not, your sensor's bleed valve, of which there are 3 styles:
pico wps500 bleed valves.png
WPS500 different bleed valves


There may be a leak/Loose screw! (I think the early ones have a service kit available or O ring?) Or maybe some other defect there abouts?

I'm sure there was once a number stated for the compression hoses volume for use in the compensation dialog box, but I can only assume that the 5.0ml is correct for the Pico supplied hoses, as I can't find anything, here or in my kit? (Steve/Alan/Phil/Mike ... anyone able to confirm this?)

Just a further thought...

Richard
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Re: relative compression test

Postby victor2k » Sat Oct 22, 2016 7:31 pm

FioranoCars wrote:Hi
This might also be a potential issue, if you have serviced, or not, your sensor's bleed valve, of which there are 3 styles:
pico wps500 bleed valves.png


There may be a leak/Loose screw! (I think the early ones have a service kit available or O ring?) Or maybe some other defect there abouts?

I'm sure there was once a number stated for the compression hoses volume for use in the compensation dialog box, but I can only assume that the 5.0ml is correct for the Pico supplied hoses, as I can't find anything, here or in my kit? (Steve/Alan/Phil/Mike ... anyone able to confirm this?)

Just a further thought...

Richard

Hello,
Let's talk about numbers:
198 psi means 13.65 bar.
In the repair manual the car manufacturer will require for more than 11 bar so the software can't tell nothing about low compression in this case.
Even if you will have 300-400!PSI the software will warn you about the low compression on a engine with a compression ratio at 10(tested by me on w7/64 bits with a non-pico pressure sensor with 6.11.12 software version).
I think is a bug related to the compresssion ratio in Pico Diagnostics :|
About the compensation for hose +adapters volume...can be measured in 20 seconds(5ml is a big compensation volume for a 1.4l engine with a compression ratio at 18-19 so if I can measure then I will not use a default/presumed compensation value).
Regards
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Re: relative compression test

Postby tangoman » Sun Oct 23, 2016 1:58 am

there must be a bug related to the compression ratio in Pico Diagnostics there is no leak in the hose in fact the kit is only a few weeks old in works great . but not when you use it on a relative compression test . it come up with great info and yes you can use it just don't look and the red bars telling you it got low compression hope the can fix the bug so it work with windows 10
when you use it to diagnose a car with say valve timing out it work great here a photo of a Nissan pathfinder 3.5 v6 with valve timing out 19 deg the customer that give me the car to check out had the car for 5 years and did not know why it was always had low power so less then 10 mins work I seen the problem
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Valve timing out by about 19deg
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