I just logged Autotap data with my 02 Z06. A few questions for the experts

1) What sampling rate are you getting? I am sampling about 12-14 parameters per second


2) How come some of the parameters are listed twice in the selection areas? For example - STerm Fuel Trim B1(%) is in there about 3 times. Is this so you can check a parameter more than once per "scan cycle". I logged some data and put STerm Fuel Trim B1(%) in there twice, one value right next to the other. The values recorded in these two fields were very different from each other, that is disturbing. See this file:
http://www.rbartick.com/cf/l3.csv

3) Is there a parameter for pulse width? I see something called Average BPW Bank 1, 2, but no Injector Pulse Width.


4) How is this thing calculating the WOT A/F ratio? My software (version 1.11 from the WWW site) is logging WOT ratios, but I thought the stock narrow band O2 sensors were not able to do that.

5) My version of Autotap crashes quite often if I stop a log session and then try to start logging a new session. If I close Autotap and then reopen it before starting my second log it will not crash. Anyone have this problem?

 

1)The sample rate goes down for each parameter you add
2)There is no reason to have parameters twice, mark the double ones and delete. You get different values because the difference in time they get measured.
3)Yes I have used it a couple of times. Do not remember which group of parameters in belongs to. Search and you will find it.
4)I have no good answer to this question. I assume it uses the data available and makes the best of it. As you say you need wideband O2's to get a accurate reading.
5)I do not use the windows versions. The DOS version is very stable and never gives me any problems. I import all data from the logfile to MS Excel to plot curves and get averages etc.

The interesting parameters to watch is the following
a)Engine runtime (gives you an idea when things happened during your run)
b)Timing
c)Knock retard
d)Engine speed
e)Throttle pos
f)O2 B1S1, O2 B2S1 (to find out correct a/f during WOT. Should read around 0.885 at WOT)
g)LTFT B1, LTFT B2 (should be around 0% in average)


I do a long run in different gears, RPM's and several WOT runs and log the above parameters. Then I import the file to MS Excel and make a total average of LTFT B1 and B2 columns/rows. When tuned with the MAFT I get this average to stay within +/- 0.5% from 0%. Next I sort the data by the Throttle pos column and makes an total average of the O2 rows that have a throttle pos value above 99.5%. When tuned with the MAFT I get this average to stay within +/- 0.01 from 0.885

This is my way of doing it. I'm sure more forum members will chime in and tell you their experiences.

:cheers:



[Modified by seanr, 8:39 PM 6/24/2002]

 

>There is no reason to have parameters
>twice, mark the double ones and delete.
>You get different values because the
>difference in time they get measured.

Check my data log posted above. I logged the items one next to the other and the difference between them was huge.

For Example my first record:

Time
73407.53

STerm B1
1.6

Time
73407.64

STerm B1
-2.3

If you go down the line you will see a lot of pretty big differences, some a lot bigger than this one. In fact if you sum the columns you will find that the first B1 column sums out twice as large as the second column. That does not sound right for such a small difference in time.

There is no selection for injector pulse width. The closest thing I see is Average BPW Bank1/Bank2. I am not sure if this is the same thing. If you check the Autotap parameter list on their WWW site they mention both Injector Pulse Width and Average BPW for various cars, so I am not sure what Average BPW is.


[Modified by rbartick, 2:10 PM 6/24/2002]

 

You are looking at the Short Term fuel trims. They jump all over the place. I do not know what you are trying to accomplish but if you are trying to get the A/F ratio correct at normal driving and at WOT it's the Long Term Fuel Trims you should look at (LTFT) and O2's. I have the Injector Pulse Width B1 and B2 selectable in the Show menu (DOS version)

I have never used the Windows version so I do not know about the menu structure. Select 'Start in MS DOS mode' in your shutdown menu and install the DOS version and try to find the Injector Pulse Width B1/B2

:cheers:

 

>I do not know what you are trying to accomplish

Just trying to have fun with this stuff. I realize the LTFT are the better values to look at, but I was surprised to see 3 instances of some variables in there (like STFT). I was also surprised to see how much this variable changed over such a short period of time. Another weird variable, in addition to O2 B1S1, O2 B1S2, etc.. I have Oxygen Sensor Volts--Bank 2 Sensor 1(mV). This value is also not even close to the reading I get from O2 B2S1 even if I read it directly after I read O2 B2S1.


>I have the Injector Pulse Width B1 and B2
>selectable in the Show menu (DOS version)


I do not have this in the Windows Version, I checked everywhere. The closest thing I have is "Average BPW Bank 1(ms)". I will probably try the DOS version.


[Modified by rbartick, 3:39 PM 6/24/2002]

 

[QUOTE] When tuned with the MAFT I get this average to stay within +/- 0.5% from 0%. :nono: Too rich

Next I sort the data by the Throttle pos column and makes an total average of the O2 rows that have a throttle pos value above 99.5%. When tuned with the MAFT I get this average to stay within +/- 0.01 from 0.885
:yesnod: Close enough

 

The O2 values fluctuates a lot when your not at WOT (full throttle) During full throttle you will see a value in the 0.85 to 0.95 area from both B1 and B2 and it's quite stable. If you are close to 0.85 you are lean, if you have a value close to 0.95 you are rich. As an example my O2's at WOT are 0.903(B1) and 0.873(B2) and together they averages at 0.888

If you are doing intake mods many cars starts to run lean. To fix the problem you can have your PCM reprogrammed or you can install a MAF Translator to tune it yourself as I described in my initial post.

:cheers:

Nice looking car you have :yesnod:

 

jawski,

Could you please explain what you mean by rich :confused: From what I've learned the PCM running optimal at 0% LTFT's. If the value goes above 0%, lets say 2% the computer is adding 2% more fuel to compensate for a lean condition. If the value goes below 0%, lets say -2% the computer removes 2% of fuel to compensate for a rich condition. Have I missed something :bb

:cheers:

 

Sean,

I have a T1-C, a MAFT, and a bunch of other bolt-ons going on the car. I wanted to baseline stock just to see where I am at before I start changing things. I did some dyno runs with wideband O2 while stock, and with just a T1-C a few weeks ago and from those results I was able to tell that I needed a MAFT and Autotap. See below. I put the stock airbox back on for now. I am not sure I would trust Autotap O2 B1 & B2 readings at WOT, that is supposed to be out of narrow band range. I am not surprised to see that my WOT autotap A/F ratios are not really close to the wideband reading I got on the dyno. I will see how Autotap reports the rich condition I got when I ran with the T1-C.

BTW - I agree with your 0% LTFT goal.





[Modified by rbartick, 4:33 PM 6/24/2002]