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Old 05-24-2018, 11:14 AM   #1
metrogdor22
 
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Does this data log look okay/normal?

After putting a CAI on my car, I took it back to the shop that installed the cam to get the tune looked at and make sure the intake didn't throw anything off.

Later I was curious and decided to data log a short WOT pull and some general driving. I'm no tuner and certainly not an expert on what I'm looking at and what it means, but I found a couple things that seem odd to me.

First is the graph of RPM (blue) vs. timing (orange). It's adding 45 degrees of timing at some points. Is that normal? I thought timing was generally in the +/- 20 degrees range. Then it fluctuates between +12 and +35 degrees at the slightest change in throttle when cruising.

Then I looked at the Short Term Fuel trims and they're all over the place. +/- 10%. I would expect the 2 banks to be similar, but they're not very close at all.

Like I said, I really have no idea what the data I'm looking at should/should not look like. The car is cammed, so that could account for the fuel trims being all over the place.
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Old 05-24-2018, 01:58 PM   #2
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What are you using for these graphs? It's hard to say if the car has a knock and the knock is pulling timing on you. Also the car could be commanding a certain timing, while also allowing modifiers, but this chart isn't looking for the modifiers.

+/- 10% is fine, it's not ideal but the car is at least trying to make it up for the changes. I do prefer to see +/- 5% though. Especially when it comes to leaning out. But it looks like when you give it gas it richens, instead of leaning.
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Old 05-24-2018, 02:25 PM   #3
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Quote:
Originally Posted by ChibiBlackSheep View Post
What are you using for these graphs? It's hard to say if the car has a knock and the knock is pulling timing on you. Also the car could be commanding a certain timing, while also allowing modifiers, but this chart isn't looking for the modifiers.

+/- 10% is fine, it's not ideal but the car is at least trying to make it up for the changes. I do prefer to see +/- 5% though. Especially when it comes to leaning out. But it looks like when you give it gas it richens, instead of leaning.
I'm just using Excel and the raw .csv log from Torque Pro.
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Old 06-22-2018, 03:28 PM   #4
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You're timing is not solely based on rpm. Actually I think you will see less of a correlation between RPM and timing nowadays than what you would traditionally expect. However there will be a strong correlation between timing and manifold vacuum(throttle position). Your data infers that you let off the gas between shifts and it looks like you take advantage of engine braking when you slow down. Some inputs that play a role are intake air temp, coolant temp, rpm , and manifold vacuum. Not sure what else. As far as your STFT, they work with your O2 sensors and the two will look very similar, all over the place. It is kind of like a self-checking diagnostic tool in the ecm. It is more of a concern when they stay positive (or negative) for long periods of time. This will be an indicator that something isn't right whether it be a faulty O2 sensor, faulty fuel delivery, or whatever.
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Old 06-22-2018, 04:45 PM   #5
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did you retune for the intake and what was on the car before that part? if you switched from the stock intake to the CAI you'll want to get it retuned for sure with the aftermarket cam installed
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