Hey, new here. Are VE tables used on LS1 cars? On MAF LT1's like mine everyone says they don't do anything.

Jeff D.

 

The VE tables are only used when the there is a failure of the MAF. And the vehicle goes into speed density mode.

 

the ve tables are used in open loop also ,right?

 

That is not correct. Many people here have had great luck with changes to the VE table for improved driveability, even without MAF failures.

VE table changes make noticable differences in LS1s behavior. I was able to rid myself of warm start and idle surging just by adjusting the VE tables in low rpm ranges.

 

Main VE is used all the time.

 

I can't speak for anyone else but


My MAF peaks out around 5,000RPM's @ 61.01 lbs per minute (12,174hz). From there up to 6500 its on VE. I can't feel or hear the transition from MAF to VE. IMHO the VE is as important if not more than the MAF table @WOT

 

Thxs for the replys. Maybe the VE's for LS1 offset some other smaller number than what they do in LT1's when recalculating BPW. Thus, having the same number make a larger change. In the LT1 OBD1, very large offsets only make like a 1-2% change.

Jeff D.

 

According to ken kelly and the ls1 edit forums the ve tables are only used during cranking or in speed density mode the main ve table is used on open loop during warm up. This is what i was told. The way i understand it the ve tables are used as a base setting to kinda start from or somthing like that, once the car is up to temp and running closed loop the MAF, map ect. take over and vary the timing and fuel curves from there. so yes the ve tables are used but only as a kind of starting point which is why, when adjusted correctly helps idle and warm starts when in open loop. but the ve tables do not directly dictate fuel and timing during closed loop or WOT.

 

Main VE table has a constant affect on closed loop fueling as well. I have proven this for myself, as have many others on this board. I tried many different values in the lower rpm ranges of VE, and the results I saw were in everything from warm starting to low rpm cruising in closed loop. Going too far one way or the other would have drastically different results (either starving the motor for air or fuel in lower rpms). As I said all results were observed in closed loop (after full warm-up, 19X* coolant temp).

I am not the only one here that has had these results.

 

...actually, I noticed very little if any changes to open loop operation when making minor VE table changes. All the differences in operation I observed after VE adjustments were in closed loop.

 

VE changes affect closed Loop too I agree

 

RPM WS6 is absolutely CORRECT.
The VE table is used in the Base Pulsewidth Equation.
This was stated and proven by NoGo (He is the MAN) and Cal several months ago. Here's the Thread
joel

 

Yep, VE is used ALL the time, and it's applied to more than just steady-state fueling. It can really affect how much fuel is injected when you are trying to accelerate. I think the thing to realize here is the GM engineers were free to use these tables how they saw fit by the way that the firmware in the PCM was coded. It may or may not do what you expect based on your past experiance or based on the technical definition of VE.

 

Wow, that's a lot of air flowing there. I'm fairly new at this, and wondering which should be more accurate, MAF or VE? You'd think the measured air flow would be more accurate than the calculated/adjusted VE curves. Would it make any difference if you had a MAF that was accurate at higher flows? The MAF table in Edit stops at 12000hz, but the MAF high freq fail is at 13874 or so. So does this mean the PCM goes to VE mode between 12k and 13.8kHz? What's the point of the 13.8kHz value? Just a sensor failure test?
Thanks for any replies...

 

After 12kHz the pcm still reads the maf freq, but the number used in it's calculations for maf flow doesn't change from the last table value at 12kHz. Once the High MAF Fail Limit is reached the pcm ignores the maf input, assigning 0 to the maf freq. and the car runs strictly off the ve tables. Very bad for FI/dry N2o, ok for NA/wet n2o.

 

My truck is FI and runs fine beyond the 12kHz. The scan tool still has an assigned value for the MAF of just over 12k but the motor doesn't stop or anything. Nor does it return an assigned value of 0 via the scan tool for the MAF. While tuning with a wide band it went lean once past the MAF limit so I adjusted the PE by RPM and also made adjustments to the PE table @ the upper end of the MAP values. I can't feel any type of transition or anything...

So I'm not sure if the MAF is really kills the everything once reaching or passing its limit at least that hasn't been my experiance with my truck.

 

Yes, I said it'll run over the 12k limit. It just won't account for the additional air in the maf calculations past 12k, the ve tables still will be used as they always are, all you would notice is a slight leaning. After the fail limit it will stop adding that maf-read value in and go considerably lean if the manifold pressure exceeds atmospheric by much.