Timing & AFR

[joshp14]

I'm tuning a 01 WS6 with blower cam and 7 psi procharger.

I've got the VE tuning done, MAF calibration done, and idle done. I now need to work on the timing tables and this is the only thing I'm kind of not so sure about. I have base idle set at 23 degrees, which it seems to like to give the best idle quality. I have warm idle set at 875. Did a run on the dyno and currently made 519/466 before any timing adjustments. I have B3618 set as:

11.945501
11.945501
11.945501
11.916992
11.916992
11.916992
11.916992
11.916992
11.916992
11.702858
11.702858
11.702858
11.702858
11.603144
11.417423
11.417423
11.417423
11.417423
11.417423

and B3605 with the WOT cells at 12.95 AFR.

When on the WOT run on dyno, the WB read down to about 10.5. Not really sure why its doing this when the tables are set as above.

Regarding timing, I have found these recommendations when searching for timing for forced induction cars:

-Pull some timing out of the timing tables over 3000 rpm,
set your commanded AFR to 11.5, raise the MAF fail frequency

-AFR to be around 11-11.5 at WOT and timing at ~ 16-18*.

-Take timing out from 0.80g/cyl up.

-Use a NA timing until 4K and then start toning it back. Use about 14 degrees on 5 psig
on these motors but run as much as 28 down low

-Use 2004 ZO6 timing table and subtract 5 degrees of timing from 2000
and up and starting at .56 DYNCLAIR and up. This is reasonable
start for a centrifigul blower with boost up to 7 psi.

Just need some insight on how to get the AFR to read properly at WOT and also how to set timing properly on a inertia dyno (Dynojet 248x)

Thanks!

EDIT - One more question, whats the diff between CALCVE and AUTOVE? Is one better than the other?

[WeathermanShawn]

When on the WOT run on dyno, the WB read down to about 10.5. Not really sure why its doing this when the tables are set as above.

EDIT - One more question, whats the diff between CALCVE and AUTOVE? Is one better than the other?

Hi there:

I'll tackle your last question..which may help you figure out your other AFR question..

CALC. VE is simply using your MAF Airflow (calibrating through LTFT's) and computing a representative VE Table. Normally its for closed-loop and cars running MAF.

AUTOVE is a technique to directly Airflow corrections to your VE Table, normally through AFR differences (BEN) between Commanded and Actual AFR. Its very popular for SD applications (open-loop) and MAFLess.

If your actual wideband AFR on the dyno is not matching your Commanded AFR..then either your MAF and/or VE Table is still not correct. Hey, even a 7% difference can be the difference between a 14.0 AFR and a 13.0.

With your Tune..you might be running out of MAF anyway, so the CALC.VE & CALC.VET may not help you out as much as the AUTOVE. One is not 'better'..they all get your to the same point in your Tune..perfect AFR..

That much of your question, I can help out. The others will require more comment.

Good luck..

[joshp14]

OK thanks for your response. I always thought that when doing autove that the cells above roughly 4k rpm werent too important to hit since PE kicks in at what like 64% TP and goes off the B3605/B3618 table, am I mistaken? When at WOT shouldnt the AFR match whats in the richer of those 2 tables? Is the VE tune important to hit those upper cells?

[WeathermanShawn]

OK thanks for your response. I always thought that when doing autove that the cells above roughly 4k rpm werent too important to hit since PE kicks in at what like 64% TP and goes off the B3605/B3618 table, am I mistaken? When at WOT shouldnt the AFR match whats in the richer of those 2 tables? Is the VE tune important to hit those upper cells?

Depends on what Tune you are running. If you are MAF-Enabled, it is true that normally above 4000 RPM its all MAF. So, the MAF Frequency vs AFR must be perfect. You would normally only 'need' your VE Table if your MAF fails. And that can and does happen, both on the street and on the track.

Whether the AFR 'picks' the richer of B3605/B3618 during PE Mode is debatable. On my OS it always picks B3618 and only uses B3605 when it first starts (cold open-loop). Thats where a good log with Commanded AFR/EQ will tell you.

So, if you are indeed all MAF..make a map of MAF Frequency vs AFRBEN and adjust your MAF directly through Table B5001. If your not running out of MAF, feel free to try the new and improved CALC.VET:http://forum.efilive.com/showthread....867#post135867

Does MAF,Trims, and VE Table all in one log. You just have to know how to put in calculated pids, and cut & paste..Let us know..

[joecar]

AUTOVE: disable MAF, disable NBO2 trimming, use wideband to correct VE table.
AUTOMAF: enable MAF, disable VE, disable NBO2 trimming, use wideband to correct MAF.

CALCVE: applies LTFT correction to MAF, then calculates VE from MAF, MAP, DAT, RPM; not suitable for PE/WOT (when trims stop).
CALCVET: selects LTFT/WB based on PE, applies correction to MAF, then calculates VE from MAF, MAP, DAT, RPM.

CALCVE/CALCVET are quicker than AUTOVE/AUTOMAF.

CALCVE/CALCVET can do both VE and MAF in a single log, but rely on the NBO2 sensors to be in good new working condition; requires filtering of non steady state conditions.

AUTOVE/AUTOMAF are more suited to dyno tuning (dyno can be held at each cell sufficiently long enough to obtain steady state conditions); can be done street, but requires careful driving/filtering to obtain good data.

Each method, when done carefully to avoid/filter transient conditions, produces same results.

[joecar]

Hi Josh,

If you run a COS (which has boost VE/timing tables) you may be able to get better control of AFR... $0.02

Tuning is difficult, is best/easier done on dyno to find MBT timing.

[joecar]

OK thanks for your response. I always thought that when doing autove that the cells above roughly 4k rpm werent too important to hit since PE kicks in at what like 64% TP and goes off the B3605/B3618 table, am I mistaken? When at WOT shouldnt the AFR match whats in the richer of those 2 tables? Is the VE tune important to hit those upper cells?

VE table gives airmass, while PE table gives AFR... VE and AFR are two different things, but both a required for computing the fuelmass.

If you're running with a MAF, it is still a good idea to do the full VE table, for several reasons:
- if MAF fails, then running from the VE will be a non-issue;
- you can compare VE-calculated airmass (DYNCYLAIR) with MAF-calculated airmass (CYLAIR);
- you have the option of changing from MAF to VE/SD anytime you want.

[joecar]

Josh,

- do you have a FlashScan V1 or V2...?
- which wideband are you using...?

[joecar]

Merged threads into one, is it ok here in Forced Induction...?

[joshp14]

Yes its ok in here.

I have V2 with LM1 wideband. It's interesting to see the difference in the LM1 pre-converter vs the dynojet in the tailpipe. The dynojet WB runs .5-.8 leaner.

I spent a couple more hours tonight re-doing the VE and MAF tables. The VE tables BEN's were around .91 when I first started and they are much better now around .98 but for some reason LTFT's are running -8%.

I redid the MAF table. I think it hit around 12k hz during the dyno run so I guess its not maxing out...yet. This dyno run it did 537HP and 460 TQ. AFR at WOT is much better at 11.5-11.8 than the 10.8 it was before the changes. I dont have a COS in this....still pretty new to tuning. Running closed loop MAF tune as he will drive this vehicle when the roads are clear all year round.

Here is the log file for the last dyno run I did. I have timing at 15.5. I had a little KR right at fuel cutoff, not sure if its legit or not. It did blow the duct off the TB on this run at the very end. How do you set timing with MBT? Can't this only be done with a load bearing dyno with instant/realtime torque readings?

Also, when are 2 bar MAP sensors required?

Thanks for your help fellas!