Clarification on PE enable.

[pavetim]

I don't remember the talbe off the top of my head. But there are 2 tables one seems really good it commands PE AFR you can set it via rpm and map. Now the other table you can only set it with rpm which seems kind of wierd, cause if you have 2000rpm but only 40Kpa it will richen it up where in actuality you'd want PE at 65Kpa. See what i'm getting at? How do those tables really work?

[WeathermanShawn]

PE Mode is primarily determined by the Parameters in B3618 and B3616 as you described.

This is where it gets trickier than you have been led to believe. B3605 is only utilized when in 'cold-open-loop', I.E. when the car is first starting up (see Table B4107). Once you are in closed-loop that Table is never referenced unless you Disable PE Mode. To do that you would need to change all of B3618 to an EQ of 1.00. Some OS's may take the richer of the two tables (B3618 & B3605), but I can guarantee it is not true in every OS.

So if you are staying closed-loop you may not even be able to use B3605. My OS won't do it, so you would have to do testing to see if that is even doable in closed-loop.

The smarter way is to look at the Parameters in Table B3613. If you want to limit PE to MAP's above 65 kPa then change that to 65. Though you may think RPM & TPS is a 'dumb' way to engage PE Mode, at 4000+ RPM it is better to hit it at 20% throttle than to wait until 65 kPa to engage it.

Most of the COS Tunes allow for a lot more control of your fueling. You might check that out at some point.

Have you tried using B3605 in closed-loop yet? May not work in the way you want it.

[joecar]

B3618 is the PE commanded AFR table with AFR x RPM on the axes.

B3616 is the enable for B3618 with TP x RPM on the axes.

B3605 is the OL non-PE commanded AFR table with AFR x ECT x RPM axes.

If you run a COS, B3605 is replaced by B3646 which is OL non-PE commanded fuel with AFR x MAP x RPM axes.

If you set the tunetool fueling units to EQR, then replace AFR with EQR in the above sentences.

[pavetim]

Ill have to look at tables again, im pretty close to afr I want think I got lucky lol. Where do I get cos and you have to buy them?

[joecar]

COS's are included for certain LS1B OS's... look in the COS tutorial (on your hard disk or at www.efilive.com/downloads).

Also note this: the PCM selects the AFR from richest of the active tables (i.e. the richest current cell from all the active tables).

Active tables means any commanded AFR table that is currently active (including COTP which doesn't have a visible table but it commands AFR 11.7).

[pavetim]

Wow that clears alot up for some reason I was thinking B3605 was for PE too, and that confused alot for me. But knowing it's not for PE actually explains so much now. Thanks guys.

[pavetim]

ok i have b3618 set to 65% up to 3200 then 35% the rest of the way up. Now in B3606 should I set PE MAP enable to 35 or 65?

[WeathermanShawn]

Tim, some of that may be personal preference.

Every engine/combo is different. Personally I leave mine at the stock setting (LS1=15MAP). For my set-up, Idle MAP, and altitude I prefer nothing inhibits PE Mode from occurring.

I don't have a problem with it engaging too easily. Test it on a few hills (if you have them) and at higher RPM's. IMO, 35 kPa is fine. If it kicks in too frequently adjust the MAP to 65 kPa..

[pavetim]

thats the tricky part i'm gonna figure out like for normal stop light driving i would like it to kick in 65kpa and lil higher rpms' like 3200. but i also want it to kick in low like you said if your at 4200 and 25kpa i'd want it to be able to kick in then. Which is possible since he has a manual so might see above 4000 rpms with low map pressures.

[WeathermanShawn]

You can always enable it at a higher TPS at lower RPM's. Like 80% if you think it is kicking in too frequently.

Another option is to use a ramped up PE AFR/EQ..say start at 2000 RPM's at 13.5 AFR then sloping to 12.8 AFR at peak TQ. IMO its more difficult to tune that way, since you have a moving AFR/EQ target. But plenty of Tuners do it. That way 'PE' kicks in, but you are not wasting fuel enrichment at lower RPM's.

I usually wait until you get it perfectly tuned before sloping the PE Mode curve..

[swingtan]

There are two major thoughts on the enabling of PE mode and they basically deal with throttle position or engine load....


Throttle Position: the basic idea is that at small throttle openings, you are only "cruising" so do not need PE mode at all. This is the way most (if not all) stock calibrations work. The basic settings for TPS and MAP are to have relatively high TPS and relatively low MAP settings. This will make the TPS setting the real governing control as the MAP values will normally always be over the setting in the tune.
Map Value: the basic idea here is that no matter what the throttle position is, if the engine load is over a set point, PE mode is enabled. This is more like the old PE valve in a carburetor that had a spring loaded plunger. If the manifold vacuum dropped below a set point, the plunger opened the PE valve and added fuel. In this case you set relatively low TPS and high MAP settings in the tune. The governing parameter is now the MAP reading and if it goes over the set point, PE mode is entered no matter what the TPS is.


The idea of altering the basic settings depending on RPM now becomes a "fine tuning" exercise for the entry/exit of PE mode. The ability to alter the commanded AFR during PE mode depending on RPM is a further enhancement and aids in both power and economy.

Simon.