How does the 7730 ECM transition between these two tables (at 1600 rpm) during operation?

The reason I ask is that at about that RPM, there's a really strange stumble. Is there something I should do at that RPM in the tables to get a smoother transition?

 

1600 rpms in the lower table and 1600 rpms in the upper table should be identical. This is true for both fueling and spark. Make sure they are not different. I've seen situations where these values were different and a 'stumble' was the result.

Tim

 

Traxion, thanks. Yeah I took a look at my tables last night and they were indeed different. I'll try it out again tonight and see if the problem is corrected.

It was wierd, when cruising at low speeds, hovering between 1500 and 2000 rpm, the engine would stumble, buck and surge, etc. I think you're probably right in your observation.

BTW, I love your tuning-tech articles. Printed most of them out and did a lot of reading, preparing for when I would solve the idle misfire problem. Now that it's solved, my tuning is progressing very quickly and accurately thanks to your expertise.

 

This "condition" also happens with the maf tables. It would be cool to know why the ecm is stumbling...ya know....like in the code...cough...cough...

 

You could always ... cough ... cough ... open up the code and track it yourself ... cough ... cough ...

lol

Tim

 

You guys need some Robitusson or something??

 

Lets just say that I don't have that ability. Besides I don't think the code explains why GM made two tables w/ the same entries..!!?

 

The code never explains WHY GM did certain things. That's left for us to interpret. However, we CAN figure out how it is doing it and in what manner. This may lead to an obvious answer as to why GM chose to do it ... or, it may not. You just never know until you track the code.

Tim

 

The table lookup routines as written will only handle a max of a 17 x 17 3d table and a 17 entry 2d table.

RBob.

 

that's why they spit them up into a table ext, this is what you are saying, right?