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New forum Member

Postby DebbieSidera » Mon Oct 21, 2013 1:06 am

I just get my Pico 4 channels with all of accessories. I'm happy. For two week I have been playing with the machine. I didn't get good results... I know that the machine could be so complex but I'll keep trying.
My first Issue. was a Ferrari 308GTS. I was comparing the results with a standard compression test gauge and the Pico. The results with the gauge were just great! but the relative compression test it shows a poor compression in one of the banks. The battery test failed all the time. To me the car start so great with lots of energy... but I have been trying several times the test and failed... Also the engine balance test couldn't be done. It shows Error. I tried to connect the positive to the battery, to the starter and of course to the alternator... but it failed. This car has a long battery wire because the battery is in the front and it has a central engine.

I want to say hi to everybody.
I'll keep working.
Debbie.
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Re: New forum Member

Postby Steve Smith » Mon Oct 21, 2013 10:41 am

Hi Debbie from Steve Smith at Pico and welcome. Well, you have arrived with a bang and now I have my work cut out. First of all thank you for posting this information which I will look into and feedback as soon as possible. One question regarding the relative compression test, once the engine was disabled can you confirm the throttle was wide open to allow for maximum airflow?
The design of the crankshaft on this vehicle may well have an effect on the relative compression test results and so I would like to know if you could send me the saved data file from your relative compression test and send it to steve@picotech.com.

Could you also send the battery test and engine balance test results so we can begin to fully understand the outcome of your tests.

Once again thanks for your posts and I look forward to assisting you soon.

Take care......Steve
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Re: New forum Member

Postby Robski » Mon Oct 21, 2013 9:04 pm

but the relative compression test it shows a poor compression in one of the banks

With current clamp or through Pico diagnostics ?

The battery test failed all the time
Also the engine balance test couldn't be done

This kinda makes me think Pico diagnostics ??

Try with the current clamp (600A or 2000A) around the batt neg cable or starter pos in the Pico 6 automotive software for a relative compression test, at the same time you could run more channels to check volt drop in the long cables.
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Re: New forum Member

Postby DebbieSidera » Tue Oct 22, 2013 7:38 am

Hi Guys! Thanks for the quick answer.

I did not save the battery test... but Yes, I saved the compression test. I did both with a throttle open #1 and close #2. This car is already gone. I trusted with my compression test gauge, the battery was ok and also the charging system work very well.

Yes I used the 600A clamp on my battery test. Note: the car had a gel battery (dry without acid). The test shows a few ohms resistance for the battery...

I just don't know if I did something wrong. I already tried the test again with another Ferrari 348GTB. It was great in all the tests.

Also I have been reading on the forum that some cars need a big load on the alternator for the engine balancing test. I just used the headlights, ...

Again, thanks for the answers.
I'll keep playing!

Debbie
Attachments
131020_CompressionTest_002.pddata
Throttle open
(75.56 KiB) Downloaded 189 times
131020_CompressionTest_001.pddata
Throttle close
(74.63 KiB) Downloaded 188 times
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Re: New forum Member

Postby Robski » Tue Oct 22, 2013 1:20 pm

Debbie,

I think you misunderstand me !

You are using PicoDiagnostics, as you have posted pddata files.

What i was suggesting that you do for a relative compression test was to use use the High Amps current clamp on the battery negative or starter positive cable in the Picoscope 6 software not PicoDiagnostics. When doing it this way disable it from starting one way or another.

You can add other channels to test for volt drop in the positive & negative side as well as running a math channel to calculate it for you.

Also whilst coupled this way (depending on current clamp location) you can enable it to start again & check the charge rate & battery recovery.

In Pico diagnostics you should get a 'strength meter' when doing a balance test for an indication if what you have on is loading the system enough to give an acceptable result.

To be honest i steer clear of the PicoDiagnostics side & stick to Picoscope 6 software as have enough accessories to carry out a test one way or another, also by this i can set up to my liking with timebase & sample etc.
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Re: New forum Member

Postby DebbieSidera » Wed Oct 23, 2013 5:20 am

Thanks so much Robski,
Yes I'll next time but I just had that F308 for a couple days with some rush... so I had no time to repeat the test. But I thing is a very good idea and I'll follow your way next time.
I like the PicoDiagnostics test because you can print a cool report for the costumer. They like it because it has all the info, it's easy and it's clean. When you show some paper sheets with only waves to the costumers they get crazy... hehe ;)
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Re: New forum Member

Postby Steve Smith » Mon Oct 28, 2013 11:50 am

Hi Debbie and thanks for the data you sent, sorry I have not responded sooner.
Looking at the data it is very strange to see that every alternate cylinder reports low efficiency which indicates one bank of cylinders, given this vehicle is equipped with a flat plane crankshaft.
If you “right click” on the psdata file you can see the signal waveform which also supports the finding of the bar graph that alternate peaks do tend to fall after higher peaks. One thing to remember is the bar graph is an average of the waveform signal for a “at a glance cylinder performance indicator” and all values are approximate. It was interesting to see the compression values did increase by 10% on cylinders B, D and H with the throttle wide open, confirming airflow is everything with a compression test. However cylinder F remained lowest at 47% and this would be my cylinder of concern. I would really love to know how the airflow is distributed throughout the intake manifold and could this have had an effect on our result, or moving onto the exhaust flow rate via the offending bank exhaust manifold?
How we interpret the bar graph results is also important and that is, Cylinder F demonstrated reduced current consumption when under test in comparison to cylinder A, and not necessarily has a lower compression to the value of approximately 50%
Factors other than airflow that come into play when measuring compression via current draw are the influence of the flywheel, inertia dampers, variable valve timing, multi cylinder engines, (8 and above), internal friction, and electrical circuit resistance ( including battery type)
We must remain mindful of all the above when carrying out these tests and confirm the results in the correct manner as you did with additional tests once potential errors have been found. (Nothing wrong there)
As a “first look” approach the Pico diagnostic compression test is a really valuable tool, but to base a major engine repair on a single” first look” test alone would be ambitious, in the same way as measuring low voltage across a battery with the engine running and condemning the alternator with no additional tests.
Hopefully Debbie if you do manage to get this vehicle back and if you have the time it would be great to carry out some additional tests to help us all understand and explain all these variables, can you send the vehicle over to me in the UK?
I can but hope, take care……Steve
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Re: New forum Member

Postby DebbieSidera » Tue Nov 12, 2013 3:58 pm

Sorry I have been out of town for the SEMA Show in Las Vegas. The F308 is gone, so I can't make any other measurement on it.
Today I have been doing the same balancing test to a F360. I don't understand... it fails! I connect the Pico Channel A direct to the alternator and the other end to a very good ground on the engine/chassis strap. The voltage indicator is ok and it drops when I start the headlights. The tests seems ok when I start the engine but it only read 400-600 rpms. Then the Pico can't perform the engine balancing test... it appears ERROR. I have been trying to clamp the positive on the starter and also different grounds location. Finally I repeated the test with more battery load using defroster, fog lights, etc. But it fails.

The car came to the shop for a big noise problem. Well it was obvious because we found that the engine mounts were completely broken. The car also had a 1160 code. I drove the car and the engine runs bad in idle but after 2500 rpm is just fine.
I have spark in all of the 8 cylinders with new spark plugs. I get signal of the injectors. The pressure of the fuel pumps had increase too much because the ECU is reading that the mixture is too lean. The code appears in both banks... two separate fuel pumps, two oxigen sensors, two of everything...
I keep working...
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