749 tuning question
04-06-2005 | 04:19 PM
#1
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Joined: Feb 2004
Posts: 26
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From: Northeast
Car: 94 Z28, 84 Porsche 928, 84 Ferrari Mondial Cab.
Engine: LT1, 4.7L V8 Vortech/749, 3.0L V8
Transmission: A4, 5 speed, 5 speed
749 tuning question
This question is referring to my supercharged Porsche 928 4.7L V8 sporting a GM 1227749 ECU. http://p-928.home.comcast.net/749.html
I've been running this configuration for over a year with 25 or so track days last season. I'm kind of new at tuning and would appreciate some pointers.
I just fixed a problem that was keeping me from data collecting so I am just getting my first good data from the '749. I added an intercooler and smaller SC pulley, and it is now going way lean as soon as the boost starts to come on. I've uploaded some data in an Excel spreadsheet: http://p-928.home.comcast.net/928-1.xls
Any hints on where to start? I've been working on several tables:
base pulse constant vs % egr - this let me get idle and off-boost fuel pretty close (although a bit rich)
ve vs rpm vs map - last season filled in some lean holes by increasing ranges in this table.
Boost multiplier vs map - made several changes here last night, increasing the 130 kPa & up areas. This 'seemed' to be moving in the right direction.
VE adder vs RPM - today I increased the upper ends of this table, 4000 RPM & up - no big difference
So where should I focus? Boost Multiplier vs map? Am I heading in the right direction?
Thanks,
I've been running this configuration for over a year with 25 or so track days last season. I'm kind of new at tuning and would appreciate some pointers.
I just fixed a problem that was keeping me from data collecting so I am just getting my first good data from the '749. I added an intercooler and smaller SC pulley, and it is now going way lean as soon as the boost starts to come on. I've uploaded some data in an Excel spreadsheet: http://p-928.home.comcast.net/928-1.xls
Any hints on where to start? I've been working on several tables:
base pulse constant vs % egr - this let me get idle and off-boost fuel pretty close (although a bit rich)
ve vs rpm vs map - last season filled in some lean holes by increasing ranges in this table.
Boost multiplier vs map - made several changes here last night, increasing the 130 kPa & up areas. This 'seemed' to be moving in the right direction.
VE adder vs RPM - today I increased the upper ends of this table, 4000 RPM & up - no big difference
So where should I focus? Boost Multiplier vs map? Am I heading in the right direction?
Thanks,
04-06-2005 | 04:32 PM
#2
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Joined: Nov 2004
Posts: 126
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If your drivability, non boost stuff is good then yes play with the multiplier
It won't do much good to play with stuff under boost if you plan to change the non boost stuff later though, as it is a multiplier of the non boost tables, changing them changes under boost also.
When I tune I like to get closed throttle (IDLE) dead on first
then cruising stuff
Then boost stuff last
Followed by timing, then slight adjustments to fuel due to timing changes.
It won't do much good to play with stuff under boost if you plan to change the non boost stuff later though, as it is a multiplier of the non boost tables, changing them changes under boost also.
When I tune I like to get closed throttle (IDLE) dead on first
then cruising stuff
Then boost stuff last
Followed by timing, then slight adjustments to fuel due to timing changes.
04-06-2005 | 05:05 PM
#3
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Joined: Jun 2004
Posts: 157
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Car: 93 GMC Typhoon
Engine: 4.3L V6 Turbo Charged
Transmission: 4L80e
Like Ty1295 after your fueling is correct for normal driving, play with the Base Boost Multiplier -vs- Map F77 table. Here is a description of what it does from Brian Green.
I would read the notes we have put up on nwstp.com and download the P4.pdf (Turbo Sunbird document) on there. Read the fueling section in the P4 document and learn it. These tuning notes will make more sense as you play with it.
http://www.nwstp.com/forum/chiptable.asp
We put these notes into the TunerPro 4.0 XDF definition for code $58.
The notes look like this in the program.
F77 is used for changing the fueling at a certain boost level. NOTE - if you change the first table entry (90 or 135 on the 3 bar) you will affect the entire fuel curve while doing anything in vacuum. I just learned this lesson on some 50lb/hr injector programs - the version 2 programs have been revised as this was an issue.
I would read the notes we have put up on nwstp.com and download the P4.pdf (Turbo Sunbird document) on there. Read the fueling section in the P4 document and learn it. These tuning notes will make more sense as you play with it.
http://www.nwstp.com/forum/chiptable.asp
We put these notes into the TunerPro 4.0 XDF definition for code $58.
The notes look like this in the program.
Last edited by skwayb; 04-06-2005 at 05:10 PM.
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