Bowtie316

iTrader: (1)

Reading the sticky here on this site Found Here, when you get to the point of tuning VE with STFT alone, it has you disable PE. Now the concern I had at first and now in another thread ctd raises a concern about is that it could possibly be damaging to the motor to tune with PE disabled.

I thought about it a bit and in my my mind decided that it would probably be OK since it wasn't adding the extra timing for PE.

I have been tuning on my stock 4.8 this way for a while with no issues and now tuning the mild cammed 5.3. I get no knock retard, and honestly, it nails down my VE table right away. I also carried this same principle on to MAF tuning and have found it to give me rock solid afrs.

Is there damage to be caused by tuning with PE disabled? If so, why does the sticky on this site recommend it?

outkast6991

iTrader: (34)

I'm not an expert but I truly don't understand why you would turn PE off. Your trims wouldn't apply to PE affected cells anyway. I'd just tune the whole table with a wb and be done with it

Bowtie316

iTrader: (1)

Thats the thing, with PE turned off the trims actually do work. You turn PE off for this reason, so the fuel trims will work.

outkast6991

iTrader: (34)

The question is why would you try to tune an area of the VE table that is never going to use trims with trims? it seems your targeting lambda in a cell that will want something far richer

redtan

iTrader: (5)

First of all, o2 sensors don't do well past 14.7...so you won't be tuning the PE area of your VE table well with narrowbands.

Second of all, you don't want to be going into the PE area of the VE table while having PE disabled. That means in high load areas where you need PE (12ish AFR) you would be running without that enrichment and doing 14.7 AFR. That will quickly melt your pistons.

You tune non PE areas with the narrowbands, and you tune the PE area with a wideband.

Bowtie316

iTrader: (1)

Because the VE table is a basic calculation of airflow. I use the fuel trims to correct the VE table to what the actual airflow of the engine is. Regardless of PE enrichment or not, the airflow should be the same. If the VE table is correct for stoich afr, then the PE commanded AFR will be very close to actual. At least that has been my findings.

I really think this type of tuning is just a different way of going about the same thing. The VE table will end up with the same number in it when it is tuned correctly.

BLK02WS6

iTrader: (2)

The point is, why would you subject your engine to running at stoich under high load in order to do that procedure? That is plain freakin stupid! The smart and correct way to do it is to use a wideband so that when you are in the high load areas of the VE table, you are correcting to the target that you actually want the engine to run at... The author claims it is not a problem to target stoich because you are only there for a split second and it won't detonate... yeah, right... Anyone wanting to use that method, have at it - I'll stick to what makes sense and use a wideband to correct to realistic and safe targeted AFRs!

2000 TA owner

iTrader: (1)

Not arguing with anyone here but I started this thread why is that a sticky if it is not valid could really mess someone like me who is new to this and I am only tuning below 4000 rpms like the sticky says because I will be using my maf when Im done So donot turn pe off just keep tuning ltft,stft as I am until they are dialed in am I on the right page

Bowtie316

iTrader: (1)

Correct, thats is why PE is turned off, so it can trim to stoich. The ve table has nothing modified to account for PE, that is done with timing and fuel adders.

Seems to me that I wouldn't be the first one to ask this question about the stickied write-up if the process was melting pistons. I'm not sure the extra fuel is needed if the extra timing isn't added. Perhaps it is, I'm just trying to get this out into the open because noobs like me are using the how-to.

MontecarloDrag

iTrader: (3)

That is what I call the Kamikaze method
It can work, but it's too risky and stupid to do it when you can buy a wideband for cheap.

The risk is too great, I wouldn't try it with my own car let alone to a customer.

redtan

iTrader: (5)

I mean heck, if you want to run full load/full throttle without any PE then be my guest, it's your engine afterall.

Every single internal combustion engine on this planet has some sort of power enrichment at high loads. But I guess all those engineers are wrong and putting too much fuel into their engines at full thorttle. You're going to prove them wrong now are ya?

2xLS1

iTrader: (25)

Ever seen a 60 second PE delay on a 6.0L stock truck calibration? Those pesky GM engineers. They do it on the 7.4L and 8.1L calibrations too. Not saying its right to do it, but they do.

redtan

iTrader: (5)

So you're saying that at high loads and high rpm (4000+) the engine has to be at WOT for a full 60 seconds before the PCM goes into PE? So basically unless the truck is raced in a full standing mile race, the engine will never see PE? Somehow I don't see how they expect a engine at 6000rpm to be running stoich 14.7 AFR.

BLK02WS6

iTrader: (2)

It is actually a 1 second delay... go check a stock file...

2xLS1

iTrader: (25)

I check them every day. Here is a 03 Silv 6.0L LQ4. Looking at it with both Tunercat OBD2 and EFI Live. 4.8L and 5.3L trucks have anywhere from 0 to 8 sec delays depending on the MY. It appears to be intentional as 6.0L LQ9 trucks have a 0 sec delay.

BTW, HP Tuners has never shown this parameter.

redtan

iTrader: (5)

I wonder if that delay is after startup. If the PE delay is truly 60 seconds then that engine will never see PE.

A truck full WOT from a dead stop will hit thpe governor long before the 60 second mark, so it will never have a chance to be full throttle long enough for PE to kick in.

Also look at the rpm delay mode bypass at 5500 rpm...that prolly overrides the time delay

BLK02WS6

iTrader: (2)

Well, 0 to 8 sec is a far cry from 60 secs...

Here is a stock 6.0L and stock 8.1L...




And if you look at the 7.4L, it is 60 seconds in one table; however, there are two other tables that override the 60 second table based on throttle position - it becomes 1 second as well...

BLK02WS6

iTrader: (2)

In case you want to see the 7.4L tables...

2xLS1

iTrader: (25)

Go datalog a 6.0L with a 60 sec delay.

2xLS1

iTrader: (25)

I have over 1400 truck files on my computer. I doubt there is anything you are going to show me I haven't seen. Here is a 04 5.3L with a 2 sec PE delay. It is delaying PE the full 2 seconds. It has the same table populated with 1s that you are showing.
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