My Car Thinks Stoich is 15:1

[ScarabEpic22]

Hey, if you don't persist you'll never solve the problem...

Sounds like something a programmer would say...

[5.7ute]

I found this post confusing.
Are you using the LM-1 PID ({EXT.AD}*10) with different analog output settings?
If this is the case these settings:
0.88333v @10:1 AFR
4.21667v @20:1 AFR

are the same as:
0.00000v @7.35:1 AFR
4.21667v @20.00:1 AFR
Which is the same as ({EXT.AD}*3)+7.35 and matches the LC-1 PID not the LM-1 PID of ({EXT.AD}*10).

Whats so confusing? This method removes any ground offset & puts the scanned values in synch with the unit. By using the lc-1 settings in the lm-1 you also get much better resolution in the scanned values. Pretty much a win,win situation IMO.

[mr.prick]

What I got from the post was that he was using ({EXT.AD}*10) with the output programmed for ({EXT.AD}*3)+7.35

Using the LC-1's output with the LM-1's PIDs.

[5.7ute]

LM-1 sae_generic.txt pid:
*CLC-00-928
V 0.0 5.0 .1 "{EXT.AD1}"
AFR 10.0 20.0 .2 "(({EXT.AD1}-({EXT.AD2}-2.5)*3)+7.35 "

The generic txt was modified to use the LC-1 - ground offset equation.

[RevGTO]

My understanding is that mr. prick's WBO2 spreadsheet is set up to cancel out the discrepancy in stoich between {B3601} and the WBO2's default 14.7.

I can say that 5.7 Ute's PID equation brought my LM-1 meter reading and logged AFR's into harmony. Changing the LM-1 default AFR to 14.6 brought it even closer to commanded stoich - my {B3601} is stock for LS1 at 14.63.

So my thought was that by using mr. prick's spreadsheet I could get my logged AFR's even closer to commanded.

This all has to do with CalcVE tuning. The more I play with it, the more I recognize that you can stretch the VE and MAF tables to compensate for one another and attain to good LTFT's at various settings. But proper AFR's don't follow ... which in my mind means that you have to start with a verified VE table and then tune the MAF accordingly ... in other words, back to AutoVE and AutoMAF.

[RevGTO]

What I got from the post was that he was using ({EXT.AD}*10) with the output programmed for ({EXT.AD}*3)+7.35
Using the LC-1's output with the LM-1's PIDs.

But you program both the LM-1 and edit the LM-1 sae_generic.txt pid to reflect the same values ...

[5.7ute]

My understanding is that mr. prick's WBO2 spreadsheet is set up to cancel out the discrepancy in stoich between {B3601} and the WBO2's default 14.7.

I can say that 5.7 Ute's PID equation brought my LM-1 meter reading and logged AFR's into harmony. Changing the LM-1 default AFR to 14.6 brought it even closer to commanded stoich - my {B3601} is stock for LS1 at 14.63.

So my thought was that by using mr. prick's spreadsheet I could get my logged AFR's even closer to commanded.

This all has to do with CalcVE tuning. The more I play with it, the more I recognize that you can stretch the VE and MAF tables to compensate for one another and attain to good LTFT's at various settings. But proper AFR's don't follow ... which in my mind means that you have to start with a verified VE table and then tune the MAF accordingly ... in other words, back to AutoVE and AutoMAF.

RevGTO, as you dig further you will notice that many parts of the tune need to be accurate for any of the auto tuning methods to work accurately. Also whenever you use any fuel with an AFR away from 14.7:1 things will get complicated real fast unless you start using EQ or Lambda units.

[WeathermanShawn]

This all has to do with CalcVE tuning. The more I play with it, the more I recognize that you can stretch the VE and MAF tables to compensate for one another and attain to good LTFT's at various settings. But proper AFR's don't follow ... which in my mind means that you have to start with a verified VE table and then tune the MAF accordingly ... in other words, back to AutoVE and AutoMAF.

I have to respectfully challenge that assertion. If your have functional narrowbands that properly switch at stoich, and your wideband is functioning properly and accurately..all CALC.VE Table is doing is computing the airmass (from the MAF), applying an LTFT correction, and applying the Ideal Gas Law and expressing it as a VE %.

See it has nothing to do with a 'verified VE Table'..if you do AUTOVE and your wideband is not correct, your results will not be accurate either. It is not the method that is giving you an improper AFR..If you do an AUTOVE and your wideband is reading .2 lean..all your values will be .2 lean.

While I will agree that everyone should do an AutoVE (preferably on a dyno) if you are going back to closed-loop and keeping your MAF..you will have to tune with LTFTS and MAF frequencies all over again. Your MAF will be driving the majority of your Trims and your spark, along with your Airflow Calculations (steady-state).

I have done about 6-8 AUTOVE's along with about 75 logs using the CALC.VE TABLE Method. Here is an example of a 1 1/2 hour Log, using an LM-2 Wideband with Serial Connection and two 1 year old narrowbands.

B3601 is 14.63 AFR (EQ=1.00).

I filtered out low ECT's, and throttle transients. The remainder shows the average AFR both in closed-loop and WOT. I have over 50 logs that all average 14.63 AFR. It is richer in PE Mode (as commanded) and the low MAPS and higher RPMS (rich decel). I still think it is your wideband. I would just upgrade to serial connection and then see how it goes..

[RevGTO]

Yes, thinking more clearly in the light of day, I recognize that conclusion was not warranted. What I have observed, though, is CALCVE will correct MAF settings such that you can get LTFT's in the desired range with a variety of VE settings. But the logged stoich varies very little ... back to the original problem.

I'm going to work with the WBO2 spreadsheet a little more and see if I can make progress. But before I do, is there any reason not to change {B3601} to 14.7 for test purposes? That would be the simplest way of canceling out the discrepancy between {B3601} and LM-1 programming.

I want to do all I can to try to solve the problem before purchasing any new product.

[WeathermanShawn]

Rev..I have wondered about that too..changing B3601 to read 14.7 AFR (EQ=1.00) to match the LM-2 programming (since you can not technically program 14.63 to the exact digit).

But, I always wondered if the PCM 'expects' its original stoich reading. Like it is hard-wired. A couple of times logging I would get a Commanded AFR of 15.35 at Idle..Still in closed-loop..could not find a table anywhere that commanded it.

So the short answer is I do not know. As a F.Y.I., I just put in a fresh wideband sensor..the only time I could get anything near leaner than stoich is if I was accelerating with a lot of Spark Advance (non-PE). So I guess it is always possible that something mechanically could cause a higher than average 'stoich'.

But, I am guessing. The best solution may be a Calculated PID that allows you to log LTFTBENS using 14.85 or higher as your stoich. Then everything would match. I agree LTFTBENS are not the most 'glamorous' way to tune..but once you get them nailed down..they barely drift and your car runs very smooth with very little variation of AFR.

It is about the best you can do in closed-loop. Now hitting Commanded AFR in PE Mode is the real art. Thats what takes some skill to consistently hit!

Later..