Data to Show Effects of Carbon Build Up?

[meissen]

Do you have a limit to how many sensors you can datalog at once? If not, throw it in there I would think you'd need to do at least a 3+ baseline runs and average the readings somehow to get a good idea on if there's any significant difference before and after cleaning. Granted this is a much newer car with the newer diagnostics and what not, but datalogging on OBD1 you can get a good idea of a baseline but each drive could show different average values based on other factors such as ambient outside air temperature, run time, heat soak, etc.

[911medic]

No limit, but supposedly the more you add, the slower the polling of each one. But I've had a dozen in the there and had no issues getting plenty of readings for each.

[911medic]

Originally Posted by 911medic

If you're referring to his comments regarding changes to the injector pulse width readings, then I can add:

• Air-Fuel Ratio (commanded)
• AFR (measured)
• Injector Pulse Width (for each individual cylinder)
• Mass Air Flow Rate

I can also add:

• Barometric Pressure
• Intake Manifold Pressure
• Vacuum
• Fuel Flow Rate/Minute

if you guys think they will be of value.

Do you think any of the Fuel Trims/Knock Retard/Timing Advance readings would be of value in this application?

I checked last night, and unfortunately AFR (measured), Injector Pulse Width, and Fuel Flow Rate are not supported. :(

[911medic]

Here are the PIDs I have set to log:

[intensifi]

I wish I had known about this before I installed the catch can, had the BG liquid and manual upper induction cleaning done.

The car definitely runs better and gets better mileage after the upgrade/cleanings. It would have been nice to measure the difference though.

[KMPrenger]

If someone REALLY wants to show the affects of running a DI engine for a long time with no catch can, they should do a dyno run.

26,000 miles may not be enough to a big difference...or maybe it is I don't know. But it would be nice to have someone dyno before doing a cleaning.

Get it cleaned. Drive a week, and then dyno again.

[meissen]

I'd add the Fuel Trims - the fuel trims is a measurement of the result of what the PCM is commanding for fuel. But the min/max measurements are perplexing to me... on my OBD1 car, 128 is considered stoich, higher than 128 is rich (the PCM is commanding more fuel to be added to the mixture) and lower than 128 is lean (PCM doesn't need as much fuel in the mixture)

[911medic]

Originally Posted by intensifi

I wish I had known about this before I installed the catch can, had the BG liquid and manual upper induction cleaning done.

The car definitely runs better and gets better mileage after the upgrade/cleanings. It would have been nice to measure the difference though.

Yeah, I hope there is some useful, measurable differences that show.

[911medic]

Originally Posted by KMPrenger

If someone REALLY wants to show the affects of running a DI engine for a long time with no catch can, they should do a dyno run.

26,000 miles may not be enough to a big difference...or maybe it is I don't know. But it would be nice to have someone dyno before doing a cleaning.

Get it cleaned. Drive a week, and then dyno again.

Yes, I agree that before/after dyno runs would be the "gold standard" of demonstrating the effects of the build up.

Unfortunately, I don't have the time and would rather spend the money on my long wish list of mods.

So, I thought with my $5 app and my $25 OBD scanner that I might be able to document the effects another way.

[911medic]

Originally Posted by meissen

I'd add the Fuel Trims - the fuel trims is a measurement of the result of what the PCM is commanding for fuel. But the min/max measurements are perplexing to me... on my OBD1 car, 128 is considered stoich, higher than 128 is rich (the PCM is commanding more fuel to be added to the mixture) and lower than 128 is lean (PCM doesn't need as much fuel in the mixture)

The long-term trims are already added (all the data points in those screen shots are what I currently have set to log). There are short term trims I could add as well.

I don't know enough about fuel trims to know what the units should be. Torque displays them as a +/- percentage; whether that's percent above/below stoich I don't know.

[911medic]

Here are the other available fuel trims that can be logged, though I'm not sure the car gives readings on all of them:

[GretchenGotGrowl]

Sensor 2 (either bank) should be after the cats. I would use sensor 1 for both banks.

[911medic]

Originally Posted by GretchenGotGrowl

Sensor 2 (either bank) should be after the cats. I would use sensor 1 for both banks.

I'll have to check when I'm connected to the car and see which ones are even available. The long-term and short-term trims don't even give a "sensor" option, just bank 1 or 2. Maybe they just average them all?

[GretchenGotGrowl]

Originally Posted by 911medic

I'll have to check when I'm connected to the car and see which ones are even available. The long-term and short-term trims don't even give a "sensor" option, just bank 1 or 2. Maybe they just average them all?

Try these two when you get a chance.