E38 VVE Setup Guide

[joecar]

Including this document for reference purpose...

[pauly24]

Got a couple of questions while following this tute.

It says to set B0141 all to 14.5
With my stock file (VE SS L98 E38) The majority of the points which would be considered in the normal operating zone are all set to 14.63.
Values under ECT of 44 are set to 17.22
and values under intake temp of 0 are extremely rich, starting at 10 and working down to 3.81 for -40.

Would it be stupid to change ALL these values to 14.5?
I mean if the engine is being started for the first time on a super cold morning, then trying to inject 14.5 would cause it to run like crap wouldn't it?

[swingtan]

Page 1, 4th sentence....

Ensure the car is up to normal operating temp before starting this.

Simon.

[pauly24]

Yes but you are changing the point in the map for cold conditions to 14.5.

So next time when you go to start your car tomorrow morning in the cold, it will go to the point for ECT of say 10 degrees and intake vale temp of 10, and it will try and inject 14.5, which is too lean and now your cold start it stuffed.

Are you saying everytime before you drive your car in the morning you must let it cough and splutter because its lean while your waiting for it to warm up? Obviously not but I don't see how it works.

I'm obviously missing something here.

[gmh308]

Yes but you are changing the point in the map for cold conditions to 14.5.

So next time when you go to start your car tomorrow morning in the cold, it will go to the point for ECT of say 10 degrees and intake vale temp of 10, and it will try and inject 14.5, which is too lean and now your cold start it stuffed.

Are you saying everytime before you drive your car in the morning you must let it cough and splutter because its lean while your waiting for it to warm up? Obviously not but I don't see how it works.

I'm obviously missing something here.

Its a good point, but maybe the tute covers this re returning to stock values after finishing the tuning session before next cold start. (?).

Certainly if you left the OL run table at 14.5 or ~ 1 EQ/Lambda it would start ok at 10C cold start (the start/cranking is a seperate fueling table) but once started it would probably run a tad rough for a few seconds until the short term trims started up (3 - 10 sec). Or may die and require a restart.

[pauly24]

But why make it so the STFT kick in, it should be set correct so the trims don't have to work, im sure if the mixture is correct first time, and it doesn't need to adjust via triming then this would give smoother operation because it doesn't stumble for a split second with the incorrect mixture.
Maybe the tute should say to only change the values of cells with an ECT over 60 to 14.5
This way you don't affect the cold start of the car.

[gmh308]

But why make it so the STFT kick in, it should be set correct so the trims don't have to work, im sure if the mixture is correct first time, and it doesn't need to adjust via triming then this would give smoother operation because it doesn't stumble for a split second with the incorrect mixture.
Maybe the tute should say to only change the values of cells with an ECT over 60 to 14.5
This way you don't affect the cold start of the car.

STFT's coming in ASAP is to minimise cold start emissions. The OL table wont be as accurate as going into CL type control with STFT's trimming. CL is always going to more accurate as it is based on immediate feedback.

And it will probably stumble for more than a split second if the OL table is set to 1 or 14.5:1 for cold start around 10C. Probably a minimum of 3 seconds if it does not stall. With an IVT/ECT of around 10C its only normally about 20-40% rich anyway (depends on IVT mult value B0146 based on MAP) and will normally run if around 20% lean. Just badly thats all.

So yes probably worth leaving the low temp cells alone, but it depends what your objective is?Are you after full SD MAFless operation?

[swingtan]

The setting of the table to a flat 14.5 is only for doing the VVE. Once you are happy that the VVE is pretty close, you can reset B0141 to what ever works for you. FWIW, it will work fine at a flat 14.63 if you want, as B0146 will help richen up the mixture when cold. Holden ran a very rich cold start, probably in an effort to dump still burning fuel into the exhaust to get the cats up to temp. I've had my car start and idle on a WB reading of 17:1 when it was around 3' one morning. Sounds pretty rough though.......

[pauly24]

I'm not sure what I want to do yet.
I'm just reading through as much stuff as I can to get a better understanding of how it works before I change anything.
But thanks, you have cleared it up now. I guess when we are tuning the car it's never running in these areas anyways.

I have another question about the tute, it says to change parameter B0157 to 70kpa, my stock tune is currently set to 15kpa.
Does this mean after you change it to 70 it will take alot more throttle opening to enable power enrich mode? So even at 60kpa when you could be under a fair bit of load, it will still command 14.5.
Shouldn't the car be running richer under these loads?

[swingtan]

Note also, that the next parameter ( B0161 ) is altered as well. This is just to reset how PE mode is enabled to make it a little more consistent.

There are two main thoughts on how PE mode should be activated...

1. Throttle Position: This is the default and basically relies solely on the throttle position to enable PE mode. The MAP setting of 15 is extremely low, so the only real control is the throttle position. This mode works pretty well if you really like economy, but it can lead to issues at times, where the car feels slightly sluggish up hills when cruising. This is because the throttle can remain fairly low, but engine load goes up ( and therefore MAP ).
2. Combined TPS and MAP: I prefer this method as it makes daily driving feel better ( though 'may' increase fuel usage slightly ). In this method, the MAP enabler is set at a point a little above the normal cruise MAP readings ( any where between 70 and 80 kPa ). The TPS on the other hand is set relatively low. Remember that in the E38, the TPS settings in many tables do not directly relate to the logged ETC-TPS PID. There is another thread on this, do a search to read about it. With this setup, the ECM can command additional fueling by entering PE mode on steep inclines, giving the engine a little boost in power. This can help greatly with drivability as you use less throttle, which in turn may prevent a down shift in an auto.

Don't forget the 3rd sentence in the guide....

This document should be read in conjunction with the “Virtual VE Tutorial” provided by EFILive, you should also read through this entire document a couple of times before actually starting any work.

Simon.