Ronny

iTrader: (1)

just read in a post yesterday that with the 7747 there is a PE delay? i believe it was said this ecu is a truck application as we are well aware. is this true and if so what was the reason for delay? could it be fuel economy, fleet MPG, or does this delay allow the AE to time out B4 the PE comes in. should this delay be removed if in fact it exists. as we are aware the AE can be invoked at lower TPS % as well as higher and PE i believe is around 70% TPS but it was said 50-60-% may provide for smoother transition rather than the "open secondaries" kick in butt. are there any other issues with running the 7747 on our light cars? did i misunderstand that post and is this post factual?

Dominic Sorresso

I always set PE delay in Constants Table to 0. You can play with that if what you'd like to do is try limiting wheel spin off the line.

7Point4

Already had this typed up, and seen this thread.. So i will just add it here...
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Hey all.. I have been lurking for a while, here and on the GMECM list. I have read alot, if not all, of the information that is available, and have studied the various hacks concerning the ECM that I have (1228747).

I have a few questions about something that was mentioned in another post, and despite looking over the hacks, both the AUMU_hac.src and the AYKK_hac.src, I can not seem to grasp exactly what is going on. There maybe a mistake or two in the AUMU hack, as it does not agree with whats in the AYKK hack, but
that is just a commenting error, I believe.

The question has to do with PE mode. There are several qualifiers for PE to be entered. There is an upper and lower coolant temp that has to be met. There are two different TPS percentages, one for normal entry and one for Fast entry to PE. A max rpm to enable PE delay mode. And there is a PE delay timer. And a WOT Fast Entry Time vs. RPM table. Also there appears to be another 2000 rpm value and a 40 mph value
used somehow.

The coolant and TPS qualifiers I understand. The delay timer seems to be straightforward. Until it gets to the WOT FE vs. RPM table. It says in the hack that the timer is decreased at this faster rate if WOT fast entry TPS is above its setpoint. But how? That is the part that I am having trouble with.

In my application, I started with a stock AUMU bin. All I have changed is some of the VE table, as I gather data using WinALDL, and start adjusting to get 126 or so for BLM's. That is going good so far. Have not tuned on the upper parts of the VE table yet. Right now, the PE delay timer is set to 5 seconds. All of the
WOT Fast entry time vs. rpm values are 101 seconds. The AYKK hack shows that in that case it is set to a PE delay time of 70 seconds, with the WOT FE vs RPM table set at 105,105,105,90,10,2,2,2,4 seconds, 800 to 4000 rpm in 400 increments.

What I am thinking right now is that I could decrease the PE delay time to 1 second or zero seconds. Lower the min. coolant value from 75c (167f) to 70c, as I am running a 165f thermostat. Decrease the RPM to bypass PE delay timer from 3250 rpm to 2000 or so. And duplicate the WOT FE vs RPM table as shown above, or maybe set it at 10,10,10,5,5,1,1,1,2.

Mainly, right now, I am trying to tune for max benefit when I run at the track, which is an 1/8th mile track.
This is really addictive. Fun and enjoyable.. But .....

Any ideas or explantions greatly appreciated...

Grumpy

It probably has to do with some EPA regulation, or fuel savings. After all, the basic intent is for truck useage. There are lots of times when towing or carring large loads, that you might need alot of throttle, for torque rather then brute HP, so having a delay in those situations, would be welcomed. IMO, it'd be for outfitting too small of engine for too heavy of duty application. There are lots of areas, ie farm country, where pickups are actually used to haul stuff.

Ronny

iTrader: (1)

7.4 ? the "seconds" you refer to are milli seconds?
it sounds like i should set this delay to zero. another email to tuner cat for more enhancements.

Dominic Sorresso

Ron,

You coming down to Chicago any time soon? Bloomington Gold is about 4 miles from my house.

Ronny

iTrader: (1)

Dom, nice to here from you. i was just there. joliet nhra 333 mph top fuel and funny car. unofficial record i think. i dont think i will be in your area. on weekends we head to central wisconsin cabin. next week hopefully the mods start again. see sig. plenum is coming off and 454 TB on. as weather warms(plenum) car is running better. ended up adding a whole lot of AE pumpshot last fall to remedy the stumble. all but gone. now i am backing some out at lower TPS and lower MAP but that all changes (maybe? ) next week. feel free to email me directly with any comments on the swap. weather has been brutal here(rain).

7Point4

The hacks and editors all refer to it as seconds. Not milliseconds.

Ronny

iTrader: (1)

Quote: "WOT Fast entry time vs. rpm values are 101 seconds."

i am missing something. that is two minute delay?

Quote: The AYKK hack shows that in that case it is set to a PE delay time of 70 seconds, with the WOT FE vs RPM table.

that is a one minute delay. i dont understand,

thanks

Dominic Sorresso

Ron,

The PE delay is in "seconds" as 7Point4 has described. If you have TC, you'll see it in the Constants Table

rattle

i run the 1227747 with $42 mask,
with PE delay timer set to 0 I loose about 1 mile per gallon but the truck pulls away from stop light just awesome (wide band confirms entry to PE with anything more than 6.9% throttle movement)

I found that setting PE delay to around 2 or 3 seconds gives good fuel mileage and reasonable throttle response from stop lights.

Now if you got fancy you would set PE delay to zero and raise the minimum throttle movement to enter PE to something like 25%.
Now you will only get PE if you give at least 255 throttle movement. I found this worked good at the track.

91 chev, 3/4 ton, 4x4, flat top piston, mild cam
17.9 is all she will do

Dominic Sorresso

I have my PE delay set to 0 but my TPS% to enable PE at 70%.
That way, it invokes PE when I mean it.

Ronny

iTrader: (1)

somewhere (Grumpy) i read a post to invoke PE at say 50% and decrease the AE values a bit to vevel out the fuel delivery. supposedly give a smoother transition rater that a big kick in pants.