I peeked at an 85 SA table and yes, it didn't have much advance. I don't recall the specifics... was like 4 years ago now.

 

Both have 35 degrees total timing at part throttle and timing drops off as 'vacuum advance' is reduced.
The stock drops off 11 degrees and the ADS-chip only drops off 6 degrees

 

This is what I'm seeing in TunerPro...JoBy mentioned it a few posts^^^6026.ecu=definition file but you need to use the import feature in TunerPro and you can save it as a xdf, too.

 

I just released a new version of WinALDL. Last time was over 14 years ago, January 2007.

https://winaldl.joby.se/

I added a tab for FAQ /Help and also to save log files to "My documents" folder and that works better with newer Windows versions.

 

Thank you... I downloaded it... I have a manual transmission so I believe I need ECM 1226430 which I saw you removed a while back stated in the readme file. What do you recommend? using 1120626 (for automatic) or the 1984 car in the configuration setting?

 

CLCC 1984 car is a data controlled carb and that is something else.

Many data streams are very similar, and not all are described in detail. The 1226026 selection is actually data stream A63. The A63 does not specify automatic or manual transmission. The data stream for 1225550 is also very similar, only a few bits on the flag data tab is different.

 

Hi Guys,

I found this thread because I was searching for any info on using an Arduino to send data to the MPG display. I wasn't surprised to see JoBy was already onto the case

I still have a bunch of eproms, an eraser and a few eprom programmers from when I used to make a single tuning change and burn a new chip, what a slow process that was!
I'm sure I still have all the files, but they are probably the same ones JoBy has shared from way back then. I'll look in the morning. I remember a guy called Matt Harris on the Crossfire Vault was working on a .ecu file, but he sold the car and that project came to a halt. This was around 2003. I'm sure I have his final version somewhere.

I currently have my old 6026 hidden up behind the dash. It's not working anymore, but it used to be tapped into the VSS and RPM signals (maybe some others, I don't remember exactly) and had it's own MAP sensor connected to both the MAP and TPS inputs. I do remember I had a pot connected across the CTS input to use as a very course calibration adjustment for the MPG. I didn't really care at the time how accurate it was, I just wanted it to work and show some numbers that at least responded in the correct manner.

I don't know why it's no longer working but plan to remove it to investigate this week.

An Arduino would be a much nicer solution though.
JoBy, are you still working on this?

 

Hi Ben,

It is still a "project" but on hold until I get some inspiration to continue.
I found some information about the data to dash from a TPI and it was similar but not the same.

I have a theory about the 1984 MPG data and wrote simple test program and tried sending something to the dash. The dash did nothing. I don't know if it was some problem with my electrical interface or program.
Then other stuff got in the way.

I probably should connect my old ECU and verify that I can update instant MPG on the dash. There is MPH data in the stream but who knows, the dash might use the internal MPH signal and it was not receiving any VSS pulses.

 

Thank Jonas.
I'm surprised to learn the MPG info sent by a TPI ECM is different as I was of the belief you could swap instrument clusters between the early years and the MPG function still operated correctly.
I plan to work on mine this week so I'll post here if I find anything useful.

 

Oddly enough my MPG readout works fine with my EBL. Something Greg and I have discussed as to why it does. I still don't know why but it's even pretty accurate after making some adjustments... maybe the 84 isn't different?

 

RBob was clever and kind enough to include the code in the EBL for the benefit of those who happened to use it in an 84 Corvette

He's probably the guy to ask about the serial data, if he's willing to share what he knows.....

 

He told me it shouldn't work lol. he would be the one whos brain to pick on that. Did Greg ever get his readout working?

 

tequilaboy provided this information:
https://www.corvetteforum.com/forums...post1604833296
From the testing I did using the 1984 1226026 I can conclude that it is a bit different from 1986-1989 data above.

Below is a short example from my data log.

Byte 1 is a flag, probably MW2 and only the first three bits are set in my test data.
I am not sure about all bits ( last two ) but this is my guess. The first 5 seems plausable.
Bit 0 - Road speed pulse occured ( Should toggle )
Bit 1 - Road speed filter exercise flag ( I don't know )
Bit 2 - Reference pulse occured ( Should toggle )
Bit 3 - 3.9 k mode ( Should be 0 )
Bit 4 - shorted mode ( Should be 0 )
Bit 5 - 10 k mode ( Should be 0 )
Bit 6 - High battery voltage ( Should be 0 )
Bit 7 - Old BLM cell flag ( I don't know )

Byte 2 is MPG and I have verified this by switching over to 10k data mode and comparing at different speeds.
Byte 3 is a counter and counting speed is affected by MAP and RPM so this must be used fuel.
Byte 4 is a counter and step length is affected by VSS frequency.
Byte 5 is a constant.

Comparing with provided 86-89 data it is byte 2 that is different. The rest could be the same.
Perhaps the dash is interchangeble between years as I don't see why MPH is needed.

 

Very interesting, thanks Jonas. I had searched for this info without much success.

 

I also did not find anything so I tried to figure it out anyway.
I analysed the data and figured out the last four bytes and I had also tried to send some test data to the dash without sucess. A few month later I found the post from tequilaboy and it was almost the same data.

 

I fixed my trip computer yesterday. I have the old 6026 behind the breadbox on the passenger side, that I installed years ago for this purpose. It has it's own map sensor which is connected to both the TPS and MAP inputs for simplicity. It also has an rpm signal and of course +12v and is connected to the serial link to the dash.
I adjusted it using a pot on the CTS input and the instantaneous MPG on the dash now matches my calculated MPG in Tunerpro as I roll along at 40/60/80/100 k/hr.

It's pretty good for the amount of effort it took.

 

Ben, do you hae WinALDL, cable and a laptop?
It would be interesting to see some data logs where the instant MPG is known to check if calculations are the same as for 86-89.

 

Hi Joby,

I do still have an old 160 baud cable I made almost 20 years ago
I've just put the dash back together so the 6026 is inaccessible again. I wanted to remove it to attach wires to datalog it with WinALDL, but I couldn't even figure out how I had jammed it in there or which way it would need to come out! I needed to connect the wire for the 10k resistor if I want to datalog it, but once I got the MPG working on the dash I quickly lost interest...

or

Do you mean log the raw data that is sent to the dash when the resistor is not connected? I *think* I remember that's how it probably works?
If I don't need to connect the resistor I think I can access the orange serial data wire without too much trouble.

I need to pull the heater core soon. The 6026 is mounted somewhere above this area so I plan to reinstate datalogging access then.

 

Yes, to scan without resistor and log the 5-byte raw data used by the dash.

 

I can do that. Give me a week or two