[rich91080]

I they gave me a answer.

here it is.

My name is Richard I currently have both tuning programs for OBDI
and OBDII. I was wondering if I could get a detail description on the
function of the VE Volumetric efficiency tables in both ODB. I done a
lot of searching and I only came up with just SD mode. I am more
interested in the use of the VE tables and the MAF. Does the MAF
sensor reference the VE tables during normal driving, and when is the
VE table accessed? If possible is there a blue print of the usage of
the tables that I could buy or download? If not could someone explain
the function of the VE tables in detail? I was told to ask a gentleman
named John that works for Tunercat.


Hi Richard,

OK, as I understand it the MAF sensor reading are used to determine the required fuel under steady state conditions. Under these conditions the PCM uses VE tables are used as a sanity check for the MAF sensor reading by calculating the expected mass air flow and comparing it to the actual MAF

Under changing conditions where the vehicle is accelerating, decelerating or
the load is changing significantly the PCM essentially goes into speed
density mode and uses the VE tables to calculate the required fuel. Once
conditions stabilize the PCM goes back to using the MAF sensor readings. I
believe this is done because the MAF sensor are relatively slow to react to
quick changes in air flow.

Best regards,

TC

the actual emanil
Hi Richard,

OK, as I understand it the MAF sensor reading are used to determine the
required fuel under steady state conditions. Under these conditions the PCM
uses VE tables are used as a sanity check for the MAF sensor reading by
calculating the expected mass air flow and comparing it to the actual MAF
reading.

Under changing conditions where the vehicle is accelerating, decelerating or
the load is changing significantly the PCM essentially goes into speed
density mode and uses the VE tables to calculate the required fuel. Once
conditions stabilize the PCM goes back to using the MAF sensor readings. I
believe this is done because the MAF sensor are relatively slow to react to
quick changes in air flow.


Best regards,

TC


-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Wednesday, November 02, 2005 3:17 PM
To: [email protected]
Subject: OBDI and OBDII


My name is Richard I currently have both tuning programs for OBDI
and OBDII. I was wondering if I could get a detail description on the
function of the VE Volumetric efficiency tables in both ODB. I done a
lot of searching and I only came up with just SD mode. I am more
interested in the use of the VE tables and that MAF. Does the MAF
sensor reference the VE tables during normal driving, and when is the
VE table accessed? If possible is there a blue print of the usage of
the tables that I could but or download? If not could someone explain
the function of the VE table?s in detail? I was told to ask a gentleman
named John that works for Tunercat.

Thank You
Richard

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cool

 

[rich91080]

He also said it works the same on OBDI and OBDII.

 

[rich91080]

everyone is out tuning VE tables

 

[Ram Air 383]

Joe Georger, the creator of VE master, disagrees and he is very familiar with tuning using VE tables.

http://home.comcast.net/~jgeorger/vemaster/

Read the notes under the EE definiton (94-95 OBD-I LT1).

I just modified my tune using VE Master. I'm going to make some Datamaster logs tomorrow or the next weekend and see if there are any changes in BLMs, especially during accelerating/deccelerating.

 

[rich91080]

Let me know how you make out i will have my camaro soon.

http://impalassforum.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=8&t=016793#000006

 

[rich91080]

Anyone wants help me put a cam in

is there a gasket kit for doing a cam?

 

[Ram Air 383]

Originally posted by rich91080:
is there a gasket kit for doing a cam?

http://thunderracing.com/catalog/?action=vshop&vid=8&pcid=157

 

[rich91080]

Thank you

 

[Ram Air 383]

Update: I scanned the PCM and didn't notice any obvious difference in BLMs or O2 readings in closed loop after adjusting VE tables with a VE master.

The car is actually driveable now with a disconnected MAF but smells richer at idle compared to the MAF mode. I'll try to adjust the VE tables more using a couple of different logs.

 

[rich91080]

Ram air log some driving and try tuning again. i did my impala 2 time and the second time i did it my blms got alittle closer to 0. i realy want to do it more but i don't have the time right now.

i am glad it is working out.

 

[rich91080]

If any body wanted to know i tuned my VE tables in SD last night and reconnected my MAF and now when i floor it at 20mph it downshifts and smokes the tires.

This is the 3rd time I am tuning and each time it gets better

 

[kevm14]

Looks like I was right about the PCM using the VE tables for transient (AE) fueling. Cool. Next time I have the Camaro, I'll try this.

Also:

I was wondering if I could get a detail description on the function of the VE Volumetric efficiency tables in both ODB.

So I guess VE works the same on BOTH generations of Ol' Dirty Bastard.

 

[rich91080]

yes sir!!! i have been tuning my impala and i got good results. i have not done the camaro. still got to put plates and insurance on it .

 

[kevm14]

If anybody still cares, I am driving my Camaro again (at least for the week) and I am going to go out and get some log data. I'm not sure if I trust VEmaster to modify my BIN for me, so I may just do a pivot plot with Excel. We'll see. And I'll post my results, positive, negative or neutral, when I get them.

 

[producers_kid]

I care

and whaddayasay let's just keep this VE tuning secret among us believers ha ha

 

[Ram Air 383]

I still care if you post before and after logs.

 

[kevm14]

Ok, I did one iteration in MAF-mode and two iterations in SD mode. The second one showed fairly little changes so I thought it was done enough for experiment sake.

I have 4 logs.

Log 1 is "before VE" and is just a MAF-mode drive around. I used this data to make the first change to VE.

Log 2 is my first drive around in SD mode. It really seemed like it needed to be in SD mode, as several have said. I guess this just confirms it. It seemed to be farther off after logging in SD than it was when I logged in MAF mode.

Log 3 is my second SD log and this is the one that showed little change to the VE.

Log 4 is "final VE" and is MAF-mode.
Datamaster Logs

Not sure how useful this data will be, but here it is. At times, it doesn't seem like the LTFTs are "right." I told VEmaster to get LTFTs to 127, and I did see 127 at times. But I also saw lower numbers at times. If I had to say anything, the trend is toward lower numbers after the VE tuning. And that makes sense, when you look at the changes to VE comparison, which follows:

Changes to VE from running in MAF mode. It removed fuel (LTFTs under 128).

First changes to VE from running in SD. It added fuel (LTFTs above 128), suggesting that MAF-mode corrections went the wrong way.

Second changes to VE from running in SD. Small corrections compare to the other ones, so I stopped here.

Finally, a look at what I did compared to stock. Nothing major here, but an overall trend of adding fuel.

Now for comments. It runs better in MAF mode, even after doing the VE. Cold start felt a tiny bit laggy in the throttle response, and it was having some trouble getting the idle to stop hunting. After it warmed up, it was decent, but after I reflashed for the final time back in MAF mode, there was a noticable difference. I can't say for sure if it's better than when I started out but it does feel pretty decent. Pretty crisp response. I'm running 87, btw. I would love to see if the mileage changes but I'd be very surprised. We shall see.

Hope this helps.

 

[Ram Air 383]

I looked at before and after VE logs. In both logs the car runs a bit rich and there is a small blm slip in some fuel cells. I don't see any noticable difference in BLM behavior. You want to keep them as close as possible to 128.

 

[producers_kid]

I find that it's necessary to allow a little settling-in time after reflashing: It doesn't take long but each cell seems to start off at 120 and then adjusts fairly quickly to where it's supposed to be. Also, call me crazy, but I set VEm to 130 and haven't yet logged in open loop mode. BTW, for those reasons, logging should begin after things have settled and at operating temp or the results will be skewed.

 

[Ram Air 383]

VE changes should have a direct effect on short term fuel trims IF they are used in the calculations. It doesn't like look this way in this logs or the logs I have done on my car. I even tried setting the whole table to a single value.