Originally posted by BM Computer Src
perhaps before you dive into trying to get an ecm with a faster baud rate for ALDL scantool usage you should see what Directscan is. It gets 18 frames per second from the GN ECM; it does not use the ALDL is is not subject to the baud rate restriction. It taps off the bus on the bottom of the ECM... You will get more data and faster from the GN ecm, using the stock ECM than you will with a ALDL based tool for the SY/TY ECM.
www.bmcomputersource.com/directscan.html
Im not trying to sell you anything, just trying to help.
First of all, I want to put out any flames that may seem to come from the following reply. I intend no flames and would appreciate none as such but constructive critisism is always welcome.
I know what direct scan is. I know what it does, how it does it, and how it is connected as far as the website where it is sold. As I said before, direct scan is only one piece of the equation. Besides, we do not want to purchase direct scan which costs over $200.
As for the other parts of the equation, the stock GN puter is slow. I don't care how many ways you want to try to tell me that it doesn't matter, I believe it does and I have proof. Compare the difference between the drivability of an 87 Park Ave. that has a 3.8 and the same EFI/ECM system as the GN with an 89 LeSabre with a 3800 and newer computer. Now I understand the 89 3800 still used MAF but the computer was much faster than the GN's and has better drivability despite the differences in the engines. It is in the computer.
Case in point: I did a MAF to Speed Density conversion on my 87 GTA. Overall power increase on top end and 1/4 mile? Not really. Drivability better? Hell yes! Throttle response and around town driving manners approched a cadillac more than resembling the F-body I was in. The engine just responded quicker than with the slower MAF computer that still had 8192 baud data capabilities (unlike the GN).
What I think Speed Density will do for a boosted application that a MAF and even a MAF Translator system cannot using the stock ECM:
The first problem with a turbo car using MAF is that the MAF sensor cannot measure intake pressure directly. The ECM can only calculate it using RPM and MAF values. The problem with this does not lie in WOT fuel and spark tables, but at the PART THROTTLE levels.
The Ty/Sy ECM (7749) adjusts spark and fuel according to manifold pressure, vacuum or boost. This means that it will be much easier to adjust timing during non-boost conditions to make the most of non-boost accellerations. What does this mean to you? Probably nothing, but then again, I think more power is waiting to be unlocked by advancing the timing to the maximum level during non-boost conditions, to not only enhance part throttle drivability, but possibly reduce turbo lag time because the engine will be operating more efficiently without boost.
Can all this be done with the stock MAF system? I am sure it can, but not to the degree that is available with the newer available systems like the 7749. Besides, the 7749 has superior diagnostic capabilities, a faster processor, and more tuneable features than any GN computer out there. These are the very same reasons why I changed from MAF to SD on my GTA.
Again, I am not trying to say that the Sy/Ty computer system will outperform the GN system in all-out performance because, to my knowledge, it has not been tried. However, I do believe it will offer superior drivability than any older, MAF based system out there. Besides, if it doesn't work, we can always try the '95 3800 Supercharged OBDI system out which is already compatible with the LT1 MAF sensor. I will keep you posted on our progress...
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