My short term 75

[LukeC]

Don't fix it now! He may want to keep it. Buy it, then fix it for yourself.... 

Even when they were new, they always were a little doughy off the line. The gearing is higher than an Alfetta. That would not be helped by big wheels.

Let me know if you need any bits. I have lots of spares. I have just decided the last TS I bought was too far gone to save as a daily driver.

[festy]

Don't fix it now! He may want to keep it. Buy it, then fix it for yourself.... 

The only reason I'm giving it back in a few weeks is because my wife thinks 6 cars is too many when I only have a single garage in suburbia. Well actually I have a double garage, but my mill takes up half of it 
That, and I can't afford another rego and it's a 91 model so still a long way off club plates.

The owner (my uncle) has plenty of other more interesting Alfas to play with, and will either sell it or part it out when I return it - or just park it next to his other 75s...

Even when they were new, they always were a little doughy off the line. The gearing is higher than an Alfetta. That would not be helped by big wheels.

You noticed the wheels
They're off a 147 apparently, the tyres on the original black wheels (which we both agreed look much better) were worn so these were fitted for the last rego inspection.

Let me know if you need any bits. I have lots of spares. I have just decided the last TS I bought was too far gone to save as a daily driver.

Thanks, or you could buy this one as a daily driver  

Seriously, if anyone is looking for a cheap 75TS PM me because it needs to find a new home.
I'd love to keep it as a daily, but nothing short of a people mover is practical with 4 young kids 

[festy]

I just went out and fine-tuned the CO adjustment (it's a software setting in my code now, instead of using the AFM screw) and made a few small map tweaks down low and went for a spin.

Oh wow, that's better 
The road was slightly damp, and I think the rear tyres traveled twice as far as the fronts.
From the way the rear was stepping out at every opportunity I'm pretty sure the LSD is working properly too

[cc]

Festy, any chance of some posts on your history with ecu software and working on cars and chips generally? eg what language is used in the chip whats the file type used in the tables. Also, how is the change in the CO emission measured and which table is being changed for the CO adjustment. Have read some of your posts on alfabb. Fascinating stuff.

[bteoh]

Festy,
Are you using TunerPro RT software to diagnose problems on the 75TS? Would the 164 motronic ecu be the same as the 75TS? I am trying to diagnose some issues with my 164 and have plugged it in using multiscanecu. It doesn't give me much info though. However, I noticed when car is idling, the software says it is "off idle" when the car is idling. Checked connectors on the TPS which appear fine. Can also hear the click from TPS when throttle just closes. Not sure why ecu may not be getting right info? Would you know what pins the TPS are on the motronic ecu?
Thanks

[festy]

Festy,
Are you using TunerPro RT software to diagnose problems on the 75TS?

Yes, using Tuner Pro RT and a plug-in I wrote (MotronicPlugin) to handle the communications.

Would the 164 motronic ecu be the same as the 75TS?

They are almost identical (assuming it's a 12V 164, the 24Vs used a slightly more advanced ECU), and yes they speak the same protocol. I've added a few new diagnostic and live data functions to my version of the TS firmware, but the factory chips have enough basic diagnostic functions to show the same information, just not as quickly.

I am trying to diagnose some issues with my 164 and have plugged it in using multiscanecu. It doesn't give me much info though. However, I noticed when car is idling, the software says it is "off idle" when the car is idling. Checked connectors on the TPS which appear fine. Can also hear the click from TPS when throttle just closes. Not sure why ecu may not be getting right info? Would you know what pins the TPS are on the motronic ecu?
Thanks

Sure, it's pin 2 on the 35 pin ECU plug. It should be grounded when the throttle is closed.
Here's a list of pin functions I put together a while ago - I can't promise the wire colours will match yours though.

[bteoh]

Thanks Festy, much appreciated

[festy]

Festy, any chance of some posts on your history with ecu software and working on cars and chips generally? eg what language is used in the chip whats the file type used in the tables. Also, how is the change in the CO emission measured and which table is being changed for the CO adjustment. Have read some of your posts on alfabb. Fascinating stuff.

I'm a programmer by trade, and dabbled with electronics a bit as a kid. And I'm inquisitive, that's probably the main reason I got into this stuff

A few years ago I decided I'd had enough of carbs giving me trouble at track days, so thought I'd have a crack at fuel injecting my Alfetta. I was intending on using an old Haltech F9 or something simple and basic like that, but then I found the pcmhacking forum and changed direction a bit - and that re-kindled my interest in electronics too.

Although I've got distracted far too often along the way, my Alfetta has gone from being bog stock to this, having built pretty much everything myself from scratch. It's not the prettiest, but it's been done on essentially a zero budget.

(as a mechanical engineer, I make a great IT guy, but it gives me something to do at least  )

Then one day there was a discussion on the alfabb where I realized the motronic was not well understood at all, and there was no DIY tuning available to the community like there is for most other marques, so thought I'd take a quick look....

These Motronic ECUs are 80's technology. They are based on an 8052 microcontroller (which is an 8051 with a few extra features) with 128 bytes of RAM plus another 128 bytes of external RAM, They also have a couple of memory mapped ADCs, and a few custom Bosch chips that implement specific functions like CAS filtering etc.
The firmware is all 8051 native assembly. With something as time critical as engine control, very tight loop timings are needed. 8051 assembly was not a skill I had before I started this
I wrote the Tuner Pro plug-in in C++ which is another language I hadn't had much to do with before either.

As for the tables in the chip (aka "bin"), they're just numbers. RPM is stored in units of 40, i.e. "100" would indicate 4000 rpm. Load is multiplied by 0.05 to get the injection pulse width in milliseconds, which is why in some of the recent posts I was describing load in terms of both raw numbers i.e. 50 or 100, and the actual injection time that represents, i.e. 2.5ms or 5ms.
Some are a little more complex to translate into real world numbers, i.e. ignition advance is (X*0.75)-23.5.
The 0.75 multiplier is because the ECU tracks timing to 0.75 degree increments (60-2 CAS wheel, so 120 CAS teeth per 4 strokes or 3* per CAS tooth, and 4 tooth "events" per tooth (low, rising, high, falling) so each event is 3/4 of a degree) - it takes a fair amount of time to work out something like that from a few hundred lines of code that look like this:

Code Select Expand

X01ff: mov a,40h ; 01ff   e5 40      e@
jnz X0235 ; 0201   70 32      p2
mov a,r2 ; 0203   ea         j
jz X021e ; 0204   60 18      `.
mov a,r4 ; 0206   ec         l
rrc a ; 0207   13         .
mov a,r5 ; 0208   ed         m
rrc a ; 0209   13         .
subb a,r3 ; 020a   9b         .
mov a,r4 ; 020b   ec         l
clr acc.0 ; 020c   c2 e0      B`
orl a,41h  ; 020e   45 41      EA
rr a ; 0210   03         .
subb a,r2 ; 0211   9a         .
jnc X021e ; 0212   50 0a      P.
inc 4fh         ; 0214   05 4f      .O
inc 4fh      ; 0216   05 4f      .O
mov a,r2 ; 0218   ea         j
mov r4,a ; 0219   fc         |
mov a,r3 ; 021a   eb         k
mov r5,a ; 021b   fd         }
ajmp X0238 ; 021c   41 38      A8
;
X021e: setb p1.2 ; 021e   d2 92      R.
clr a ; 0220   e4         d
mov r0,a ; 0221   f8         x
mov r1,a ; 0222   f9         y
mov 50h ,a ; 0223   f5 50      uP
mov 76h ,a ; 0225   f5 76      uv
clr 26h.1 ; 0227   c2 31      B1
clr 26h.2 ; 0229   c2 32      B2
setb 24h.1 ; 022b   d2 21      R!
setb 24h.2 ; 022d   d2 22      R"
clr 24h.3         ; 022f   c2 20      B
clr p1.2 ; 0231   c2 92      B.
ajmp X027e ; 0233   41 7e      A~

   
The CO trim I was adjusting wasn't a measurement, it was more like an air/fuel ratio adjustment with no feedback - an idle mixture adjustment. With an O2 sensor the ECU does have feedback which is what closed loop operation is.

These AFMs have a little trimpot (the blue rectangle in my earlier photos) that offsets the fuel mixture when the ECU is running in non-cat mode. It's there so when these cars are being "smog tested" the idle fuel mix can be adjusted to minimize emissions. The reason I moved that to a software setting was because there are no spare analog input pins available on the ECU, so to add new functions like MAF learn or wideband I needed to free up an input.

If you're interested in the inner workings of a Motronic map I'm happy to explain it all, but it's a pretty dry topic 

[Duk]

The CO trim I was adjusting wasn't a measurement, it was more like an air/fuel ratio adjustment with no feedback - an idle mixture adjustment. With an O2 sensor the ECU does have feedback which is what closed loop operation is.

These AFMs have a little trimpot (the blue rectangle in my earlier photos) that offsets the fuel mixture when the ECU is running in non-cat mode. It's there so when these cars are being "smog tested" the idle fuel mix can be adjusted to minimize emissions. The reason I moved that to a software setting was because there are no spare analog input pins available on the ECU, so to add new functions like MAF learn or wideband I needed to free up an input.

Just out of pure curiosity, what are the potentials of integrating the now spare analog input as a proper analog TPS signal to effect acceleration enrichment?
It was 1 of the major reasons why I moved away from using the Nissan ECU on my V6, in that the acceleration enrichment is based on AFM/MAF signal change. But the whole thing is, from my understanding, plumbing volume sensitive. If someone wanted to add a turbo or supercharger and use a decent intercooler, then considerable volume (some litres) will be added between the AFM and the TB.

Oh, and awesome work! 

[festy]

If someone was going to add a decent turbo or supercharger, I would recommend they throw the old Motronic in the bin. These ECUs have limited potential, and I'm already heading into "beating a dead horse" territory 
Yes, I suppose it wouldn't be too hard to use the CO ADC channel for a TPS to improve AE response.
But this is the *only* ADC channel I can really free up, and I'm already using it for WB or MAF (depending on the modes enabled) so it's a pretty rare resource!

Currently AE is calculated by the delta change in AFM as you described, there's a simple lookup table for that.
AFM deltas under 4 don't trigger AE, but my recent logging makes me think that it could be triggered slightly lower without negative impact, which should speed up the triggering - it's easy to try so I'll let you know how that goes  

[cc]

thanks for the background post on the 13th october.
I have a few of questions!
There is a guy here in Brisbane who used to service afm meters, when the meter had a fine wire in them (the car was a vl commodore) and he said that  the old type of afm would 'drift' and not calibrate correctly.
Do you think modern afm's and oxygen sensors as on my 2002! 156 V6 also go out of calibration?
Can any drift be re calibrated by editing the programmed  table in the chip?
Sure would be cheaper than replacing the oxygen sensors.
The other question is more of a request! whats an AB, an AE or adc? in the 24th Oct post.
Had a look at the tuner pro web site mentioned in some of your posts. Are tuning definition files on the net for  156?
Is re programming  the chip an interest that can be developed/understood easily? Or something that shouldnt be learnt on the daily driver!
thanks