Hi, new to tuning and i cant seem to figure out how to get the desired idle to increase from 800rpm. I set the idle speed vs temp table to idle no lower than 1100rpm. but when i run the car and datalog, IAC is at 0, and desired rpm is 800. Car does not want to idle below 1000rpm. 383 stroker, 2.05I 1.6E, comp cams xe268h, and so on... just need to know if there is another parameter that overrides the rpm vs temp table or what i am missing?

Forgive me for not knowing really anything about programming, and if this is a stupid question.

Thank You

 

If you started with AUJP there is a maximum desired idle speed limiter. It is set to 800 RPM, won't idle higher then that.

I can't recall who found this but here is the code that does it. Can change the #$40 to change the maximum allowed idle speed:

RBob.

 

Awesome! thank you so much!

What program are you using to be able to view the code like that?

 

It is from a disassembly of the code in the PROM. You can change the RPM limit via the hex editor in TunerPro. Go to locations $426C and $4270 to access the RPM limit values.

Then the conversion, $40 (hex) is 64 in decimal. Idle RPM values are in increments of 12.5 RPM. So 64 * 12.5 = 800 RPM.

Say you want to change it to 1100 RPM, divide by 12.5, = 88 (decimal). Convert to hex for a value of $58. Replace both of the $40's with $58, commit changes, and done.

Although, IIRC, you need to make any parameter change via the XDF and then save the BIN. Otherwise the checksum won't get updated via the hex editor changes (fast flashing SES).

RBob.

 

Thank you very much, I cant express how much you have helped me, and how thankful i really am! I got the values changed and will be programming and trying it out tomorrow morning!

I am in the process of a restomod '70 chevelle, and down to the finishing touches, and this issue has been holding me up. Once again thank you!

 

You're welcome. Note that you can also set the RPM limit to the maximum of 3200 RPM by changing the $40's to $FF's.

RBob.

 

RBob! You just explained something I've been trying to figure out for too long. Never understood how to do hex on TP. Now when people post addresses I'll know what to actually do. Thank you

 

914Mula, glad that my posts helped. Just be aware that there are two address in use here. There is the physical PROM address, then the virtual address that is used once the PROM is in the ECM.

The firmware uses the virtual address as shown in post #2 (above). Here is that same code without the mnemonics:

On the first line the LC26B is the virtual address, set up with the L in front to show it as a label. The assembler requires this to mark a location to be able to branch or jump to it.

Remove the L and the address is $C26B.

However, when required to change the PROM data need to use the physical address. With the virtual address starting at $8000, need to subtract that to get the physical PROM address.

$C26B - $8000 = $426B, which is the address in the PROM used when hex editing.

Knowing the MaskID and where the virtual address starts is enough to figure out whether a poster is showing the virtual or physical address.

Note that you can use the Windows calculator in scientific mode to convert between hex & decimal.

RBob.