I ask this because on a friend's solid roller 383 miniram car we had my scanner going during a couple runs of his. He shifts the car at 6500 RPM with a real autometer tach mounted on the steering column, but the scanner (EASE) shows a max of 6375 RPM and flatlines at that amount until the shift occurs and the RPM come back down.

On my own car a superram 350 if I missed a shift I've also only seen a high of 6375 on my scans even though my rev limter was set to 6450 and the car definitely bounced off of it.

Thanks.

 

could be the simple fact that 255 x 25 = 6375 rpm so thats the largets value the ECM data stream can show. as far as i know. basically the 165 can keep going in rpm until it runs out of clock speed which i think may happen near but dont hold me to this 8500 rpm of so. as for your S/D car id be willing to be that the delay in teh adld showed a lwer value what was really going on.

 

As funstick said, for the ALDL data stream, the RPM is stored in a single byte in the stream. There are 25 RPMs per bit and there is a maxiimum 255 bits in a single byte. Thus 255 x 25 = 6375.

It is strictly a display issue due to the single byte RPM field used in the ALDL stream. The ECM (both 165 & 7730) have another RPM field it uses with a "double byte" RPM field to work with. That is what is checked for the "fuel cut-off" based on engine speed.

However, it does raise an interesting question of why the programming for 165s & 7730s needs to be reviewed for a very high revving engine. All of the tables that I'm aware of in the various bins that use RPM as a index for both ECMs never exceed 6,400 rpm as the max entry.

 

Is there anyway to change this 6400 rpm limit with a source code modification?? I'd like to build a motor for a 7000+rpm shift, but if I can't tune above 6400 that seems kinda of dangerous.

 

you can still look at the aftermarket tach and tune... athough its not nearly as nice....


athough if you rewrote the way it sent the data, you would then have to rewrite the scan software to read the modified datastream.

 

No problemo...

 

So does that mean that you are currently working on it??? Maybe it will be in the aldl, eprom emulator and flash chip programmer? More details please.

 

What I mean is whatever people want to do with their ECM binary that affects the ALDL datastream output, I'd be glad to accomodate them. Different RPM scalars are included in that regard...

 

Wow, thanks for the info. Looks like if I ever swap out for a stealthram or miniram I'll definitely ditch the 165 and go with something that can at least show me whats going on.

 

me too.

or, better yet, you can accomodate yourselves. The next version of my software will allow you to define your datastream however you like.