Looking for DME BIN files

[Tom]

I've read a number of stories about the KLR inspiring the J&S system - apparently they are quite similar.

Back on the idle map path, is 2.5v the actual path trigger in the code or is it a 5v digital hi-low switch with hysteresis and all that? Just mulling pull down resistor values pending Joe's input...

[johnb]

I've read a number of stories about the KLR inspiring the J&S system - apparently they are quite similar.

Back on the idle map path, is 2.5v the actual path trigger in the code or is it a 5v digital hi-low switch with hysteresis and all that? Just mulling pull down resistor values pending Joe's input...

It's definitely a simple threshold - the value read from Channel 5 of the ADC is just compared to 128 and if it's less than that, then the normal code path is used. Otherwise the alternate path is used. Since the reference voltage for the ADV seems to be 5v, that 128 should correspond to 2.5v. I bet if you put different values in those 2 maps and then grounded pin 28 with the engine running, you'd see the idle change.

[Tom]

I've read a number of stories about the KLR inspiring the J&S system - apparently they are quite similar.

Back on the idle map path, is 2.5v the actual path trigger in the code or is it a 5v digital hi-low switch with hysteresis and all that? Just mulling pull down resistor values pending Joe's input...

It's definitely a simple threshold - the value read from Channel 5 of the ADC is just compared to 128 and if it's less than that, then the normal code path is used. Otherwise the alternate path is used. Since the reference voltage for the ADV seems to be 5v, that 128 should correspond to 2.5v. I bet if you put different values in those 2 maps and then grounded pin 28 with the engine running, you'd see the idle change.

If I'm reading the schematic right (big if), that signal has a 2.2k pull-up to 5v. Right? If that's right, the pull-down resistor would need to be smaller than that, maybe 1.5k-1.8k to stay safely under 2.5v. Of course, I have no idea if the Ftech DME has the same pull-up... Might need to do a little testing tomorrow. For sure if I put 1200 rpm in one map and 800 in the other, it should be pretty obvious when it switches over....

[johnb]

I've read a number of stories about the KLR inspiring the J&S system - apparently they are quite similar.

Back on the idle map path, is 2.5v the actual path trigger in the code or is it a 5v digital hi-low switch with hysteresis and all that? Just mulling pull down resistor values pending Joe's input...

It's definitely a simple threshold - the value read from Channel 5 of the ADC is just compared to 128 and if it's less than that, then the normal code path is used. Otherwise the alternate path is used. Since the reference voltage for the ADV seems to be 5v, that 128 should correspond to 2.5v. I bet if you put different values in those 2 maps and then grounded pin 28 with the engine running, you'd see the idle change.

If I'm reading the schematic right (big if), that signal has a 2.2k pull-up to 5v. Right? If that's right, the pull-down resistor would need to be smaller than that, maybe 1.5k-1.8k to stay safely under 2.5v. Of course, I have no idea if the Ftech DME has the same pull-up... Might need to do a little testing tomorrow. For sure if I put 1200 rpm in one map and 800 in the other, it should be pretty obvious when it switches over....

Hmm I'm not completely sure how to analyze that either...yes there's a 2.2k but then there's a 47k (R682) resistor between that and the ADC input. Ground is tapped between them. So I'm pretty sure this puts the ADC input 5 to 0v (and that's what I saw when I tested it). But I don't really understand how they came up with those resistor values.

[Tom]

Hard to know whether Joe kept any of that either. If he repurposed that ADC input, I guess there's no reason to assume he kept anything Bosch attached to it. I'll see if I can gather any clues with the multimeter, but hopefully he'll come with the final word on how/where to add a simple pull down resistor on the board.

[Tom]

Well I grounded the MAP sensor input and the idle routine worked like stock, taking the normal path to the 3-cell idle control. A/C idle control worked too, as you'd expect on the normal path... So this all seems to confirm the issue, and makes me think the pull-down Joe has in mind will do the trick.

I poked around to see if some pull-down value was obvious but that's probably above my pay grade. The actual voltage on that line seems to be .66v, but the multiplexed ADC must be ghosting as best I can tell and giving a false high from the previous channel. My guess anyway, I'm sure @FTECH9 will sort it with ease.

[johnb]

While we're waiting for that, Tom have you noticed any subtle changes besides the steady-state idle speed? I ask because reading the code, I noticed that there's a map that seems to be used for an rpm flare, for startup and possibly also for coasting with the throttle closed. These are higher rpm values that replace the normal idle target rpm, but are then decreased gradually until they get back down to the normal target level for the current temp.

Does you rpm flare up above idle now more than before when starting? Or when rpm is dropping with closed throttle, does it linger above idle a little before settling down? I haven't figured out the logic 100% but I think it's pretty close to what I'm describing here and it doesn't seem to be used the same way in the alternate path that your car was using.

[Tom]

While we're waiting for that, Tom have you noticed any subtle changes besides the steady-state idle speed? I ask because reading the code, I noticed that there's a map that seems to be used for an rpm flare, for startup and possibly also for coasting with the throttle closed. These are higher rpm values that replace the normal idle target rpm, but are then decreased gradually until they get back down to the normal target level for the current temp.

Does you rpm flare up above idle now more than before when starting? Or when rpm is dropping with closed throttle, does it linger above idle a little before settling down? I haven't figured out the logic 100% but I think it's pretty close to what I'm describing here and it doesn't seem to be used the same way in the alternate path that your car was using.

I haven't actually driven the car since confirming the two paths. It should be very easy to test that, however, as it's just a matter of shorting and un-shorting two wires on the MAP pigtail.... Will do that a little later in the week and report back.

[Dave W.]

While we're waiting for that, Tom have you noticed any subtle changes besides the steady-state idle speed? I ask because reading the code, I noticed that there's a map that seems to be used for an rpm flare, for startup and possibly also for coasting with the throttle closed. These are higher rpm values that replace the normal idle target rpm, but are then decreased gradually until they get back down to the normal target level for the current temp.

Does you rpm flare up above idle now more than before when starting? Or when rpm is dropping with closed throttle, does it linger above idle a little before settling down? I haven't figured out the logic 100% but I think it's pretty close to what I'm describing here and it doesn't seem to be used the same way in the alternate path that your car was using.

I know of a similar parameter in the M-Tune called 'Idle Return Delay' that affects how quickly the ISV decrements down to idle speed once the idle switch is triggered. The stock chip uses 2, my stock APE chip uses 4 and the M-Tune uses 6. I have a lightweight flywheel with an aluminum clutch pressure plate which has very little momentum. Sometimes when I push in the clutch the idle speed would drop too quickly and undershoot the idle rpm, then surge back up a little. I tried adjusting this up to 10 and the idle was nice and smooth with no surging or hunting, but there were times when the idle would stick around 1500rpm and wouldn't drop lower. Right now I'm using 8 and it works well.

[johnb]

While we're waiting for that, Tom have you noticed any subtle changes besides the steady-state idle speed? I ask because reading the code, I noticed that there's a map that seems to be used for an rpm flare, for startup and possibly also for coasting with the throttle closed. These are higher rpm values that replace the normal idle target rpm, but are then decreased gradually until they get back down to the normal target level for the current temp.

Does you rpm flare up above idle now more than before when starting? Or when rpm is dropping with closed throttle, does it linger above idle a little before settling down? I haven't figured out the logic 100% but I think it's pretty close to what I'm describing here and it doesn't seem to be used the same way in the alternate path that your car was using.

I know of a similar parameter in the M-Tune called 'Idle Return Delay' that affects how quickly the ISV decrements down to idle speed once the idle switch is triggered. The stock chip uses 2, my stock APE chip uses 4 and the M-Tune uses 6. I have a lightweight flywheel with an aluminum clutch pressure plate which has very little momentum. Sometimes when I push in the clutch the idle speed would drop too quickly and undershoot the idle rpm, then surge back up a little. I tried adjusting this up to 10 and the idle was nice and smooth with no surging or hunting, but there were times when the idle would stick around 1500rpm and wouldn't drop lower. Right now I'm using 8 and it works well.

Interesting, thanks! In the code that uses this, the stock chip uses 2 in some cases and 1 in others. It's hard to figure out the meaning of the flags that control it but I'm pretty sure the other purpose of this routine is to make the engine flare on startup and then sink back down to the target idle. If you're interested in tweaking it for any reason it's the byte right after the 02 (i.e. 11F9=02 and 11A0=01).

Also, when it got stuck using 10, which chip was that? I'm not sure why that would happen.