Greg E
03-20-2012, 11:52 PM
Got side tracked for a bit while going thru the peripheries tonight. Bit 00 of periphery 1 in the periphery table is labeled as something called Lean Spool.
I like Merlin's description best of what exactly this does.
LEAN SPOOL is a tuning enhancement Mitsubishi employ to reduce the turbo spool time. A gasoline engine will produce hotter exhaust gas and more power at an AFR of 12.5:1 than 10.5:1. It achieves this by running a leaner AFR duing the rapid engine acceleration period than is set-out in the fuel map and in the process produce more torque. All of which results in quicker on-road car.
So when I was peaking thru the code over the weekend tracing down how IPW is calculated I stumbled on this area of the code. There were 4 table references but they pointed to an empty table. Oddly though, there were 2 axis references and they were populated with a header and values! 3 of the tables shared 1 axis with 14 elements and the 4th had only 7. The unit of measure was RPM.
Well tonight, I stumbled across this area of code again tracing periphery 1. Digging deeper into the logic, it came very clear what exactly this section of code was doing. Brought out the DSM disassembly and sure enough, the logic is identical! Lean Spool!
Enabling bit 00 alone won't do anything. Just lag the processor unnoticeablely slightly as it reads thru this code, goes to the empty table look up and adds 0 to its IPW calculation.
So what I did was create 4 tables in open memory, link them into the code and populate their values. Here's the result.
http://i.imgur.com/c4XNo.jpg
Lean spool starts at 3000rpms and stops at 6000rpms. These were the values already programmed in memory. It's best to edit these values to match when your turbos first start to spool. The default value in the code is 3000rpms, but on most TD04 turbos, you might want to set this to closer to 2200rpms. I don't see any point in editing the coolant value.
The Lean Spool Load table is the point above which lean spool will activate. Again, since these values are tuned for the more laggy TD05 turbos, you might want to drop them to something more conservative. My stock 98 sees 1psi at about 75-80 load in 3rd gear WOT.
The Lean Spool AFR table is how much leaner your AFR will be off the High Octane fuel table. If you want to run .5 AFR leaner, then set the AFR in this table to .5 AFR leaner than the AFR in your fuel table. I wouldn't go past 14.7 unless you enjoy playing with fire.
The Lean Spool Trailing Time - Rich Side table controls the time of Lean Spool operation through the RPM band. The units you see in the table are how long it will take to return to the normal High Octane fuel map. You'll have to play around with this to see what works best for you. The values populated here are the stock DSM values.
The Lean Spool Trailing Time - Lean Side table controls the time to go from the High Octane table to the Lean Spool AFR table. Again, these are the stock DSM values.
There are a couple other values not pictured. One is the AFR MAX value (16.1 by default) and the other is the AFR Enable value (13.0 by default). These are self-explanatory.
To be honest, with TD04's (especially the billets!!) spool is so fast, this feature probably isn't necessary and might be better off left disabled. I'll play with it on my car for a bit and post results.
You TD05 and bigger guys though will probably love this feature! It's the next best thing to VVT.
I like Merlin's description best of what exactly this does.
LEAN SPOOL is a tuning enhancement Mitsubishi employ to reduce the turbo spool time. A gasoline engine will produce hotter exhaust gas and more power at an AFR of 12.5:1 than 10.5:1. It achieves this by running a leaner AFR duing the rapid engine acceleration period than is set-out in the fuel map and in the process produce more torque. All of which results in quicker on-road car.
So when I was peaking thru the code over the weekend tracing down how IPW is calculated I stumbled on this area of the code. There were 4 table references but they pointed to an empty table. Oddly though, there were 2 axis references and they were populated with a header and values! 3 of the tables shared 1 axis with 14 elements and the 4th had only 7. The unit of measure was RPM.
Well tonight, I stumbled across this area of code again tracing periphery 1. Digging deeper into the logic, it came very clear what exactly this section of code was doing. Brought out the DSM disassembly and sure enough, the logic is identical! Lean Spool!
Enabling bit 00 alone won't do anything. Just lag the processor unnoticeablely slightly as it reads thru this code, goes to the empty table look up and adds 0 to its IPW calculation.
So what I did was create 4 tables in open memory, link them into the code and populate their values. Here's the result.
http://i.imgur.com/c4XNo.jpg
Lean spool starts at 3000rpms and stops at 6000rpms. These were the values already programmed in memory. It's best to edit these values to match when your turbos first start to spool. The default value in the code is 3000rpms, but on most TD04 turbos, you might want to set this to closer to 2200rpms. I don't see any point in editing the coolant value.
The Lean Spool Load table is the point above which lean spool will activate. Again, since these values are tuned for the more laggy TD05 turbos, you might want to drop them to something more conservative. My stock 98 sees 1psi at about 75-80 load in 3rd gear WOT.
The Lean Spool AFR table is how much leaner your AFR will be off the High Octane fuel table. If you want to run .5 AFR leaner, then set the AFR in this table to .5 AFR leaner than the AFR in your fuel table. I wouldn't go past 14.7 unless you enjoy playing with fire.
The Lean Spool Trailing Time - Rich Side table controls the time of Lean Spool operation through the RPM band. The units you see in the table are how long it will take to return to the normal High Octane fuel map. You'll have to play around with this to see what works best for you. The values populated here are the stock DSM values.
The Lean Spool Trailing Time - Lean Side table controls the time to go from the High Octane table to the Lean Spool AFR table. Again, these are the stock DSM values.
There are a couple other values not pictured. One is the AFR MAX value (16.1 by default) and the other is the AFR Enable value (13.0 by default). These are self-explanatory.
To be honest, with TD04's (especially the billets!!) spool is so fast, this feature probably isn't necessary and might be better off left disabled. I'll play with it on my car for a bit and post results.
You TD05 and bigger guys though will probably love this feature! It's the next best thing to VVT.