MichiganSkip

We've all read the tutorials that tell us what the tables are, but can someone come up with one that tells us what to change for a specific problem or how to bump up the performance and why? For instance, the MAF tables, what are the numbers under the frequency values for, and what effect will bumping them up or down do and WHY.... The offset vs battery voltage table. What are those numbers , what will changing them do and WHY >>> Things like that would really help out us dummies.

MichiganSkip

C'mon guys, I need some help!!!!

andy katzelis

I doubt you'll find anyone to tell you very specifically what your asking. Every car is different, and people tune in many different ways. Instructions, therefore are more general providing a global understanding of the concept leaving the specific aplication up to the individual.

Make small changes, test, and learn.

LWillmann

In an attempt to answer your questions, I will explain things as I understand them. I could be wrong, but this explanation makes sense to me.

The MAF table:

The values are grams/second of airflow for a given frequency returned by the MAF sensor. Values between data points are interpolated (calculated) by the PCM to give a nice smooth line.

So, for x frequency returned by the MAF sensor, the PCM interpretets this to be y amount of air. It then determines how much fuel to add, which it then double-checks based on the o2 readings.

Adjusting the MAF table up or down will change the fueling.

If you log the mass air flow (MAF) and fueling, and see that the PCM is consistantly adding fuel, you might try looking in the MAF table for the corresponsing frequency, and adjust it upward to cause the PCM to naturally add more fuel at that point, reducing it's tendency to add more fuel on top of the base fueling. Likewise if the PCM is pulling fuel consistantly, you'd want to reduce the value in the table so the PCM starts with less fuel so it doesn't have to pull as much.

You MUST be careful with the MAF table though, you want a nice clean smooth line, sharp changes in the values can cause sluggishness and surging.

As for the injector constants vs voltage...

It makes sense that if there is less voltage, the injector will not open as far (plus the pump will pump less fuel), so it will have to remain open longer to get the same amount of fuel into the engine. So, the lower the voltage, the higher the amount of time that the injector needs to stay open.

Increasing the values will cause the injector to say open longer, making the car richer. Decreasing them will cause them to close sooner, making the car leaner.

MichiganSkip

Thanks Lee, that's the type of explaination I was looking for

MichiganSkip

Lee, my Datamster logs show gms/sec recorded, not frequency

LWillmann

Riight, so what you have to do is find the frequency that matches that g/sec in the MAF table, and increase the g/sec value in that cell to tell the PCM there's more air flowing at that point.

REMEMBER, SMOOTH line!

MichiganSkip

I see, Now can you explain to me what a smooth line would look like?
Thanks for the help, you don't know how much I appreciate it Lee!

LWillmann

What I mean by a smooth line is that you need to make the changes gradual..

For example:


If you have 10 cells and you want to add 5 grams/second to cell 5, then you need to gradually build to that total amount, starting with cell 1 and then gradually return back to stock at cell 10. That makes the curve or line as smooth as possible.


01 02 03 04 05 06 07 08 09 10
+1 +2 +3 +4 +5 +4 +3 +2 +1

And actually, it would probably be better to spread the changes out even further, like say make the increase over the 10 cells before and the 10 cells after the point where you want to center the adjustment.

I hope you understand what I mean here.

If you plot a line with the values from the table, it forms a line or curve upward. What you want is to maintain a smooth line or curve upward, you don't want any jagged or sharp changes outside of that curve.

MichiganSkip

I see, so I could import the stock values into a spreadsheet and plot them, then make a new graph with new values and make sure they follow the same curve??? Thanks, I'll try that and see what hapens.
I did notice today when I pulled the plugs that the Pass side had #4 and #2 were wet and #6 and #8 were dry. All the plugs were a nice brown color though(both sides) I'm thinking maybe injector problem? That would explain why it's running MORE rich on the right side.

LWillmann

You have mail...

MichiganSkip

Didn't come through. Try
x2ndchildhood@hotmail.com or michiganskip@netscape.net

Off to work!

LWillmann

Sent it to both of those this time.