This for a 91 3.L auto

Ok as I understand it Volumetric efficiency is how efficient the motor is as being a air pump, basically.

If I understand right.....100% VE would mean that the enigne is preforming at it peak efficiency(filling the cyliners with the max air the can hold). What i am confused at is why are my values so much lower then this. I also understand that 100% is basially very very hard to get and rarley happends. But my values say at 4000rpms at 100kpa are 64.06. Then after that they fall lower. Isnt VE values in corrilation with the torq curve of the engine???

Am i suppose to add the main VE table and the VE adder table together to get the total VE value??? If that is the method then @ 4k rpms, my (stock bin) tables add up to 94.14. This would make sence since the little V6 has the most torq at that rpm.

Sorry if these are newbe questions but I am a newbe and the stickys are much more advanced then I am since Im still learning the concepts of tuneing(mainly, what to tune).

 

Ditto.

 

... there is a little more to it than that.

 

I know there is but thats where im at right now. Ive been reading about it for a few days now. A week ago I didnt even know what VE even stood for....But just so i understand the tables on tuner pro I Add the base table and the additive table up, correct?? And since the base table stops at 4k rpms, i continue to use the additive table along with the 4k rpms and its specific MAP value??

I hate to ask these q's but in the stickys and such those comments are way over my head as Im just learning. Sorry for cluttering another post.

 

I'm with fasteddi. I'll be getting the Moates cables etc. for Xmas and installing Tunerpro and starting to data log. I've been reading the stickies for a while and following assorted links and searching the internet etc. and so far I haven't found any book or article that explains the code and supporting tables/parms from the beginning. Is there a primer out there? It's taking a long time to pick up this stuff in little bits and pieces.

 

The $88 mask has 3 VE tables. The initial VE table is always used. This one is at address:

$83B

A look up is done (by RPM only) and the value stored.

The ECM then decides which of the other two VE tables to use. If at idle and the RPM is less then 1600 the VE table at this address used:

$7EA

Otherwise, if not at idle, OR the RPM is at or above 1600 RPM, the VE table at this address is used:

$765

The result from the initial VE table is added to the result of the second table (whichever is used) for the final VE value.

> And since the base table stops at 4k rpms, i continue to use the additive table
> along with the 4k rpms and its specific MAP value??

Yes.

RBob.

 

Thanks RBob!! Just wanted to make sure that i somewhat understainded what I was reading in the stickys.


I plan to do some data logging this weekend when the weather is better but for now ive been changing a few things on the copy of the $88 mask, bin for my car.

I do have a question on the files I have (azty) $88, it has 2 fans on the chart. My car only has one fan. Can i just zero out fan 2? Im trying to clean up the parameters that i dont need to have. And change little things that dont affect the cars performance..Ie. top speed fuel cut out, stuff like that.

 

I think you can reset the rev limiter too to a useful value. I believe I read it was set to something like 9k. ???

 

Off the top of my head i know that my rpm max limit was about 6225 for the fuel cut out and the cut in was at 59?? something. I didnt mess with that since i doubt ill ever get to those rpms, its nice to know what its set at though for a safty barrior. What ECU was set at 9k?? that awful high, sounds like someone changed the values or something.

 

There is control for only one fan in the code. There are two sets of temperatures though. The first set is for when the vehicle speed is below a threshold (70 MPH in AZTY), the other set for when above that threshold.

Most TPI calibrations have the rev limiter set above 9K RPM (w/$8D mask).

RBob.

 

Setting the rev limit that high is in effect an easy way to disable it because none of our engines would ever get anywhere near that high. I think someone had an explanation as to why GM did that but I can't remember. I'd like to set it to 5.5 or 6k as a safety measure. Any reason for not doing that?

 

Only time not to use a fuel cut rev limiter is if there is another source of fuel. Such as spraying alcohol or using aux injectors.

RBob.

 

Well In the file i have, azty (90 f-body 3.1L 700r4) bin. and $88 xdf. It has fan 1 and a fan 2. There is on/ off set temps Vs. Hi/low mph and there is also the MPH threshhold for both fan 1 and fan 2. and a few other settings for both?????? Why are there two fans??

 

That's what I get for taking only a quick look at the code. You are correct, there is fan control for two fans in the code. Although AZTY only make use of one of them. The CTS thresholds for fan 2 are set at 151*C (maximum).

As for why there is code for two fans, that is what was spec'd for the code developers. Other then that, I don't know why.

It is the same for the $8D mask ('90-'92 TPI engines). In this case the f-body cars have two fans, but only one was ECM controlled.

The same mask ($8D) in the y-body ('90-'91) has both fans under ECM control.

The up side is if you upgrade to a dual fan set up the ECM can be used for the 2nd fan. If I am correct it will be on pin F8.

RBob.

 

Ok thanks RBob!!

 

Ok I removed the air system when i worked on the engine this fall to clean up the engine bay a little and shed a few lbs.

I have read many times that when you remove the air system the engine may run a little leaner then normal and the AFR are more sporatic to read when data logging without changing the air enable coolent temp on the bin. If i changed the temp threshhold to 151.25 which is like 300 F degrees will the totally disable the air pump and the problems that it may cause throwing off the o2 sensor values?