Hey NoGo
04-13-2003, 10:26 AM
#1
TECH Resident
Thread Starter
iTrader: (3)
Join Date: Nov 2001
Location: Richmond, VA Where fast cars, well......are hard to come by.
Posts: 979
Likes: 0
Received 0 Likes
on
0 Posts
Hey NoGo Maybe you can help, no one on the mailing list wanted to touch this one.
I got an injector offset table for the svo 42# injectors I have. I put this in my edit file in hopes of running closer to the way they really act. I figure it worked, or is at least closer, since with the stock table I had to drop the flow rate table down considerably from the calculated value to get it to run ~0 on the ltrims (from about 6 to almost 4). With the new table, I have come back a little over half way to the calculated value, and it's still a tad richer so I could go back a little more. But I had one problem, at idle the o2's would hang rich in the 900mV range. Even though it was in closed loop, it couldn't do anything about it. So I played with the offset table by putting sections of the stock table back in here and there since I knew that would idle fine. I finally found where the idle section of the table is, but here's the weird part, the 11.5v-18v, 60-80kPa range. Why would a high manifold pressure area affect idle? At idle I'm reading about 27-28kPa I believe.
Any ideas?
I got an injector offset table for the svo 42# injectors I have. I put this in my edit file in hopes of running closer to the way they really act. I figure it worked, or is at least closer, since with the stock table I had to drop the flow rate table down considerably from the calculated value to get it to run ~0 on the ltrims (from about 6 to almost 4). With the new table, I have come back a little over half way to the calculated value, and it's still a tad richer so I could go back a little more. But I had one problem, at idle the o2's would hang rich in the 900mV range. Even though it was in closed loop, it couldn't do anything about it. So I played with the offset table by putting sections of the stock table back in here and there since I knew that would idle fine. I finally found where the idle section of the table is, but here's the weird part, the 11.5v-18v, 60-80kPa range. Why would a high manifold pressure area affect idle? At idle I'm reading about 27-28kPa I believe.
Any ideas?
04-13-2003, 11:31 AM
#2
Re: Hey NoGo You have to keep in mind that pressure is referenced two different ways in LS1 Edit and autotap (or whatever your using). There is absolute pressure and vacuum.
Absolute pressure is the amount of pressure present over absolute vacuum (or 0 pressure).
Vacuum pressure is the amount of pressure below atmospheric pressure (or ~101.3 kPa)
Soooo, with that in mind, whenever you are measureing MAP or looking at a table referencing MAP you have to determine whether or not it is referencing MAP as a vacuum or as absolute pressure.
When you measure MAP, you are measuring it as 27-28 kPa. We are going to assume that you are measuring MAP as 27-28 kPa ABSOLUTE. To convert this to VACUUM REFERENCED we need to subtract it from 101.3 kPa (a perfect vacuum on a vacuum referenced table is 101.3 kPa).
101.3 kPa - 27.5 kPa = 73.8 kPa vacuum pressure
With this in mind, I am going to say that you are measuring MAP as absolute, and the table that you are editing is referencing MAP as a vacuum pressure.
The table that you are editing is going to put WOT at 0 kPa (or no vacuum), and idle at 65 to 75 kPa.
Here are some examples of how different MAP tables are referenced.
Injector Flow Rate table: Vacuum referenced
Injector Offset: Vacuum referenced
Fuel Air Multiplier: Absolute referenced
Crank VE: Absolute referenced
Main VE: Absolute referenced
Secondary VE: Absolute referenced
IAT MAP: Absolute referenced
Good Luck,
Kevin
Absolute pressure is the amount of pressure present over absolute vacuum (or 0 pressure).
Vacuum pressure is the amount of pressure below atmospheric pressure (or ~101.3 kPa)
Soooo, with that in mind, whenever you are measureing MAP or looking at a table referencing MAP you have to determine whether or not it is referencing MAP as a vacuum or as absolute pressure.
When you measure MAP, you are measuring it as 27-28 kPa. We are going to assume that you are measuring MAP as 27-28 kPa ABSOLUTE. To convert this to VACUUM REFERENCED we need to subtract it from 101.3 kPa (a perfect vacuum on a vacuum referenced table is 101.3 kPa).
101.3 kPa - 27.5 kPa = 73.8 kPa vacuum pressure
With this in mind, I am going to say that you are measuring MAP as absolute, and the table that you are editing is referencing MAP as a vacuum pressure.
The table that you are editing is going to put WOT at 0 kPa (or no vacuum), and idle at 65 to 75 kPa.
Here are some examples of how different MAP tables are referenced.
Injector Flow Rate table: Vacuum referenced
Injector Offset: Vacuum referenced
Fuel Air Multiplier: Absolute referenced
Crank VE: Absolute referenced
Main VE: Absolute referenced
Secondary VE: Absolute referenced
IAT MAP: Absolute referenced
Good Luck,
Kevin
