HumpinSS

iTrader: (1)

Pe or WOT. So the car stays in closed loop all the time. If this can be done I feel it would be a lot easier for tuners to hit the high map and RPM values.

Discuss

jimmyblue

iTrader: (11)

Set the enable MAP to something you'll never reach?

WS6snake-eater

or just change your PE values to 1.0 all across the board. This way you will still enter PE but it will not change the AFR at all. ie... 14.7 x 1.0 = 14.7

Matt

HumpinSS

iTrader: (1)

the PCM will choose the riches value from the open loop fuel air table if i set PE to 1.0

WS6snake-eater

Good point.

I also suppose you could change all points in the open loop F/A table to 1.0 also. Actually if you changed the PE to 1.0 and the open loop F/A to 1.0, you would be able to set a truer VE Table, upon startup-idle conditions, becuase the PCM would be commanding the true stoich AFR upon startup as opposed to an adjusted one. If you are using the stock o2's, then this might be the way to go due to them being more accurate at stoich. For example when you 1st start the car you are in open loop, and your commanded AFR is being adjusted by the F/A vs coolant temp table, to be something other than your requested Stoich value. If you are trying to use the stock o2 readings, they will be showing the adjusted AFR, as opposed to stoich. This could through some tuners off base while looking at the o2 output. Any inexperienced tuner might still be trying to adjust his VE table for that coveted 450mv (14.62857) at idle. In doing so they are actually adjusting incorrectly.

Let's say upon 1st startup I'm at idle (1000 rpm 65kPa on my car) . I am still in open loop and my ect is about 158*. The F/A vs ECT table is telling the PCM that my AFR should be 16.23 = (stoich 14.62857 * F/A adder of 1.11). The stock o2's are not accurate at that level. In the unexperienced tuners mind they think they should be seeing somewhere close to 450mv (stoich). However this is not the case because of the adder. So the inexperienced tuner try's to make adjustments to the VE in order to get the desired 450mv. In acutallity all he just did was screw up his VE. The same could even be said if you were using a wideband. Here I am at idle in open loop, and I'm looking at a WB that is showing that the AFR is 16.23. An inexperienced tuner would be like WTF, and try to adjust VE.

I guess what it all comes down to is this. If you change the A/F vs ECT table to 1.0 for all points and change the PE table to 1.0 for all points, it will take out a lot of variable that could get in your way while tuning SD. Either using your WB or stock o2's you can tune the entire VE table for one set value. Then when you re-load the A/F vs ECT and PE tables, everything "should" fall right into place.

P Mack

iTrader: (6)

I think a safer way to hit those values without worrying about detonation would be to use a wideband and try to get your commanded afr to match your actual afr. I mean do you honestly want to run your engine at 100 kpa, 4500 rpm at 14.7:1?

If you don't have wideband, you can still get on a dyno with wideband with your mafless tune, set your pe to the actual value you want, and then make changes to your ve table until the wideband readout falls in line.

I guess if you did this you'd still have to put 1 in your open loop tables.

jimmyblue

iTrader: (11)

I agree with this approach; if you can log the commanded
AFR and your wideband AFR results, take the ratio and
then somehow "histogram" it on the same RPM, MAP bins as
the VE table, you'd have it knocked. And if you can't get a
histogram, a double-sort (by RPM, then MAP) on the Excel
table would be pretty close to as useful.

HumpinSS

iTrader: (1)

Or just wait till a cable is available and do it that way..... damn i am getting restless wating for this cable

WS6snake-eater

No ****.