Just some thoughts and observations

ctuinstra

Goblin Guru
We have the Pro Feature set now and are able to do data logging without a laptop riding along. Also using the WB AFR on an analog channel instead of the serial and the data seems a lot more accurate and more in sync.

One of the first things I noticed is the LTFT (Long Term Fuel Trims) are off a bit on the low end. It seems to be adding fuel in general all over the low end. Last time I did actual tuning (VE and MAF) on the car was in June/July of last year. The weather was quite a bit warmer than today during this logging of around 55-60 degrees. I'm sure the air density is much higher today then it was last year when it was 85 thus making it lean. I'm probably going to tune again when it's around 70-75 and really try to dial it in.

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Also Kaleb was watching the AFR and it really seems to be spot on. Two things we noticed, and these are just my thoughts on it.

1) There is a really weird time when the COMMANDED AFR (AFR Cmd) goes really high and then really low for no apparent reason and nothing to do with driving or the state of the engine. I also went back to some of the earliest logs I had and the same thing is there also. It only seems to do it once. I can only assume the ECM is doing it on purpose to check something such as the state of the second O2 (after the cat), or it's running some type of test.

Notice the AFR Cmd goes up to 16.40 and then straight down to 12.50 and spends time at each regardless of what the engine or driver is doing during this time. It only happened once and early during the drive. It would be interesting if others log this same thing.

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2) He could not get PE (Power Enrichment) to become active until it seems like TPS (Throttle Position Sensor) was at ~55% or higher. I'm sure there are other factors that come in to play, but this was one of the few times that the AFR Cmd was more rich than 14.7 most of the trip. As expected, it went from 14.7 to 11.80 which is exactly the ratio in the PE table.

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The PE EQ ratio. 14.70 / 1.250 = ~11.80

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I would like for the PE to come in a little earlier and ramp in a bit slower. I know the ramp, just not sure if the trigger can be changed. On other ECMs, there is a torque table for it, not so much here.


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Again, just thoughts. Not really a problem or issue. The log file is included just incase anyone wants to see more of the data.
 

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