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How do you determine which cylinder is cranking at what rate? Pull all the plugs except one, then use some instrument to measure the crank speed during the compression stroke? Try to guess by ear?

Enlighten me: what is Pico?

IMO the OP got low-ish numbers for all cylinders.
Pico is a brand of oscilloscope. It is an awesome tool, very intuitive and user friendly. A relative compression test w/ a scope consist of putting an amp clamp around the positive battery cable and then putting a second lead onto the signal wire for any of the 6 coils. The engine is disabled so that it won’t actually start (on European cars I usually pull the fuel pump relay), then the engine is cranked for several revolutions to capture a waveform.

As the engine is turned over by the starter, the compression of air in each cylinder causes the starter to draw more amps, which is depicted by peaks on a wave form that correspond to each compression event. On the QV you would count out six peaks on the graph from the oscilloscope and look for them all to be very close to the same maximum height.

The second channel on the scope, the lead attached to the coil signal feed, allows you to determine which cylinder is which—provided you have the engine firing order. In the graph below you can see the engine is a 6 cylinder because the firing event (red waveform) happens every 6 compression events (blue waveform). What you hope to see on a healthy engine is that all the peaks of the blue waveform are close to the same height. (The one depicted is not a healthy engine)


The pressure transducer is used to go “in cylinder” and get a waveform of what is happening inside a particular cylinder. If you find a peak that is lower or higher than the others, you can use the pressure transducer on that cylinder to “see” what is happening in that cylinder—are the intake valves closing all the way, is the engine timing off, are the exhaust valves all closing fully, is the exhaust restricted, etc. I don’t have a pressure transducer, so I haven’t done that testing, but it can be more informative than a leak down test and quicker.

There is a ton of information on the internet, and PIco shares their info and how to do these tests via videos on YouTube. “Trained by Techs” also put out some quality videos of how to use an oscilloscope to do a relative compression test.

I would be interested to see a waveform generated by @kumar_a ; car.


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Discussion Starter · #42 · (Edited)
The dealer wasn't too enthusiastic poking around on a car that isn't exhibiting any obvious problems/current CELs and is modified. I had to call in a favor with the service director who I've known for 15 years just to have them do a compression test.

There's a high end Italian mechanic here that does Ferrari and Lambo repairs: Norwood Auto Italia. I'll see if they're willing to tackle the engine diagnostics.
 

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Im sure you can get a bottom end built for not too bad. At this point you probably only need a hone and maybe new rings. If the cylinders are scored really bad you would still just be looking at a minimal bore to clean it up and custom pistons/rings. You wouldnt need to sleeve it unless there was way more damage than just a little low compression, or unless you just want to, and theres really no need for new rods unless you find an issue in there. Though its always possible that the scoring some people have found is due to ever so slightly bent rods...
 

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Im sure you can get a bottom end built for not too bad. At this point you probably only need a hone and maybe new rings. If the cylinders are scored really bad you would still just be looking at a minimal bore to clean it up and custom pistons/rings. You wouldnt need to sleeve it unless there was way more damage than just a little low compression, or unless you just want to, and theres really no need for new rods unless you find an issue in there. Though its always possible that the scoring some people have found is due to ever so slightly bent rods...
This maybe the fix but you can't get internal engine parts yet.
 

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Probably going to get some trade in valuations this week. If I can get ~$50k like KBB is showing, might be time to move on.

Would you say it's unethical to trade the car in knowing the results of the compression test? It runs fine so far. They usually wholesale traded in cars to some random auction across the country.
I would find out what’s really wrong with it first. Might be easy fix or turbo related under warranty.
 

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Discussion Starter · #47 · (Edited)
I tried the local Ferrari shop I mentioned and they said they're too busy with projects to work on it.

Just emailed service director asking if they have a PICO Scope in order to a relative compression test.
 

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This maybe the fix but you can't get internal engine parts yet.
Custom and/or lots of research. You can go to just about any of the piston manufacturers and get custom pistons if needed with surprisingly little effort for getting a custom part like this. If it really just needs a hone and rings that should be reasonably straightforward to achieve. It might take a little bit of buying the wrong parts to find out what you need, but for example a complete set of 488 rings, which there is a better than average chance that the rings are the same, is only $150
 

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Post those numbers after that run. Going to make a few this week myself. Our DA should be around 500. Dam good for here.
With fresh new heat-cycled Toyo RRs. So traction hopefully wont be an issue.
 

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Discussion Starter · #59 ·
Needless to say, I never did the 60-130 runs. Decided it was better not to risk blowing it up that way.

I am assuming those PICO results dont mean anything/weren't done properly??? 22% seems really low LMAO.

Was trying to figure out whether I can keep driving the car or just dump it ASAP.
 

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Needless to say, I never did the 60-130 runs. Decided it was better not to risk blowing it up that way.

I am assuming those PICO results dont mean anything/weren't done properly??? 22% seems really low LMAO.

Was trying to figure out whether I can keep driving the car or just dump it ASAP.
Once you don’t trust her you gotta dump
It. It’s over. You’ll never look at her the same again
 
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