AUTOSCOPE.EU

Hey,

I had a 2002 Subaru Outback come in today with an 2.5 SOHC engine. (I believe that's the EJ25 engine)

It was running rough, so I ran the CSS script. Here's what I got.
I looked at the toothed wheel screen, and was surprised to see a 6-1-2. I've never seen that before.
After doing a couple other checks, I decided to check timing.
So, based on this, it looks like it's actually a 12-1-2-1-2. Is it possible that's why the CSS script is showing 2 cylinders underperforming, because it's looking for 4 power strokes when there are actually only 2? Is there any way to correct the script and tell it what kind of toothed wheel the car has? Is it possible that because this car has DIS coils, it's seeing a spark every 6 teeth and assuming that it's got a 6 tooth crank wheel? Is there any way to adjust the trigger settings so it will only see the power stroke spark on the #1 wire, and not the exhaust stroke spark?

Well, it's not pretty, but I got it to work.

I was thinking that if I could somehow weaken the sync
pickup signal, that might allow me to only get the power
stroke sparks, and not the exhaust stroke sparks.

I let the vehicle run with the scope trigger set to the sync
channel, then moved around the sync clip until I could get a
consistent pattern. I found that if I pulled the clip about
half an inch away from the wire, I could get a pretty good
pattern. So, I rigged something up with a couple pieces of
cardboard.
After doing that, the CSS script correctly identified the
CKP pattern.


I'm hoping I can find an easier, more reliable way of doing
this in the future. I work on a lot of Subarus.

zap wrote: ↑

Fri Jul 27, 2018 1:16 am

Is it possible that because this car has DIS coils, it's seeing a spark every 6 teeth and assuming that it's got a 6 tooth crank wheel? Is there any way to adjust the trigger settings so it will only see the power stroke spark on the #1 wire, and not the exhaust stroke spark?

zap wrote: ↑

Fri Jul 27, 2018 8:44 pm

I'm hoping I can find an easier, more reliable way of doing
this in the future. I work on a lot of Subarus.

As you correctly have identified, the application has a hard time differentiating between compression and exhaust spark events, even though there should be a significant amplitude difference between the two.
There is a possibility you have a defective spark plug wire. You can try to sync from one of the other cylinders, preferably from, in this case, the other coil assembly.

If you want to try with the existing recording, go in to the script configuration and select sync on cylinder "Other", then in the next window select cylinder "12" (cylinders 1 and 2), instead of "1".
Actually, you set the application up to trigger on the companion cylinders, so if the firing order was 1324, the setting would be 12.

Very interesting.

So, for the vehicle pictured above, I would put the sync probe on cylinder 1, and enter 14 in the "other" box?

Is this the recommend sync setup for all DIS vehicles, or should I only use this method when I have trouble getting a good result with the default settings?

I notice that when I run the script this way, the cylinder labels now read "cylinder 1,2" and "cylinder 2,1". Can I be confident that the line for cylinder 1,2 is definitely cylinder 1, or does that mean that it could be cylinder 1 or 2?

zap wrote: ↑

Sat Jul 28, 2018 7:22 pm

So, for the vehicle pictured above, I would put the sync probe on cylinder 1, and enter 14 in the "other" box?

Hi,
This method should be used only when compression spark differs a little in amplitude from exhaust spark.
Let's look at the example of this 6-cylinder engine with the firing order 165432. For such an engine the following sync options are possible:
1      (1 _ _ _ _ _),
6      (_ 6 _ _ _ _),
5      (_ _ 5 _ _ _),
4      (_ _ _ 4 _ _),
3      (_ _ _ _ 3 _),
2      (_ _ _ _ _ 2),
14     (1 _ _ 4 _ _),
63     (_ 6 _ _ 3 _),
52     (_ _ 5 _ _ 2),
153    (1 _ 5 _ 3 _),
642    (_ 6 _ 4 _ 2),
and
165432 (1 6 5 4 3 2).

The script automatically checks whether you entered the companion cylinders correctly, and in case an error is made, it automatically corrects it.

But, let's go back to the engine with the firing order 1324. Cylinders 1 and 2 are served by one coil, and cylinders 3 and 4 are served by another coil.
If we have a large sync pulse amplitude for only one cylinder, we need to specify only one cylinder in the sync setting. For example, cylinder 1.
When the amplitude of the pulses is the same for several cylinders, we can indicate that sync occurs in several cylinders. In this case, cylinders 1 and 2 have a common ignition coil. The exhaust spark of cylinder 1 is compression spark for cylinder 2. If the amplitude of compression spark and exhaust spark is the same, then we indicate the sync "12". But, in this case, the script can't know where the sparks of cylinder 1 and cylinder 2 are. Therefore, the script notes these graphs as "1, 2" and "2, 1". Analogically, the script can not distinguish cylinder 3 from cylinder 4.
In this situation, to identify cylinders during the test accurately, one of cylinders can be disconnected for a short time, for example, injector connector of cylinder 1 can be disconnected; then it will be easy to understand which of the graphs belongs to cylinder 1.

PS:
If possible, check the resistance of cylinder 1 high-voltage wire because it can be defective.

Okay, thanks for going over all that with me.

If I have a chance before the vehicle leaves, I'll check out that spark plug wire.