GMs Tables and Lookups (what they did with the LT1)

[SleepyKeys]

I thought I would post of some of my stock GM tables. I pulled these from my 1994 Chevy Camaro PCM. I'm not suggesting that we should do it this way, but thought it may server some usefulness in terms of reference as there is a lot of discussion about correction factors and so on. I must say I'm impressed with how consistent the engine performed not matter how hot/cold good gas/bad gas etc event with the o2 sensors disconnected.



Obviously this is a engine/trans controller so many of the lookups don't apply to EMS. But there are quite a few correction lookups. If anyone wants me to dump a table feel free to let me know.




I think our speed-density implementation will be too imperfect to utilize .1% lookup resolution. However I could be wrong and please don't hesitate to let me know.

I would like to see VE represent VE and not be masked by varying AFR. The VE table could be multiplied against a AFR target value or Power Enrich value.

[thebigmacd]

I'm with you on this one!

The way I used my Megasquirt setup is with the AFR target table in MS1Extra, this way the VE is a true VE and if I want to change AFR i just change the AFR target table. I don't know why anyone would prefer to do it any other way, but many do, especially the experienced tuners it seems.

Coincidentally, I just got my ALDL interface cable last night (95 Roadmaster LT1). I too will be able to pull tables if needed.

The best part about the GM system in my opinion is the fact that you can disconnect the MAF and it runs on speed-density just fine. Or you can actually code the MAF out completely if you want.

[Fred]

OK, no excuse this time people :-)

Basic features

* Tuning AFR AND VE table based

http://www.diyefi.org/forum/viewtopic.php?f=8&t=3

It's been TOP of the list since the very start :-)

Admin.

[thebigmacd]

OK, no excuse this time people

Basic features

* Tuning AFR AND VE table based

http://www.diyefi.org/forum/viewtopic.php?f=8&t=3

It's been TOP of the list since the very start

Admin.

I wasn't really lamenting any assumed lack of this functionality, more questioning why experienced tuners tend to argue against it. I suppose because they don't use logging software to tune, which I do.

[SleepyKeys]

In fact you can unplug the MAP and the MAF and it will run in Alpha-N mode(TPS only). Personally I don't see a need for all these backup modes. I will be 100% content with a VE/AFR only system.

In the future I do how ever thing it would be neat to use a MAF to quick tune the VE table. This would save considerable time on a new setup. After it was "quick tuned" you can use o2 feed back to really dial it in.

[thebigmacd]

In fact you can unplug the MAP and the MAF and it will run in Alpha-N mode(TPS only). Personally I don't see a need for all these backup modes. I will be 100% content with a VE/AFR only system.

In the future I do how ever thing it would be neat to use a MAF to quick tune the VE table. This would save considerable time on a new setup. After it was "quick tuned" you can use o2 feed back to really dial it in.

see my post in the firmware feature thread

[Fred]

I wasn't really lamenting any assumed lack of this functionality, more questioning why experienced tuners tend to argue against it. I suppose because they don't use logging software to tune, which I do.

I'd guess speed of tuning. If you have two things to adjust to get where you are going, it will probably take something up to twice as long. It certainly is quick and easy up front to just tune ve and integrate AFR into it. Speaking of which, it needs to be lambda in code or it will all get rididculous quickly. Translated on the PC side for viewing if desired.

Admin.

[SleepyKeys]

You can calibrate the MAF on the bench(or find a calibration table for it, of course this table would assume you are using the same circuitry as the OEM which you are likely not) and it should perform fine once installed on the engine. I was saying this.

1. sweet I just got my new motor built and ready to fire

2. ecu is setup in MAF mode initially, this maf mode will use the MAF readings and generate a VE table that is close

3. Put the the ecu into SD mode and use wide band o2 feed back to dial the ve table in


Just an idea, I have had problems with tuning engines(too much cam) where wide band feedback was false because of an overly rich mixture(miss fire). Nothing imperative to FreeEMS just a half-baked idea. Anyway time to clear off my desk to make room for my proto hardware and my optical distributor.