Tightmopedman9

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The AC routines of the '97 850 GLT are partially different from the 607/608 AC routines.

Amongst other things two RPM dependent lookup tables were added in the 607/608 bins.

I changed the AC routines of a  607 bin to match the AC-routines in the 97 850 GLT bin.

I think that will do the trick, but it has to tested when Chuck W is back in the US

 

Edited by Piet

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On 11/27/2018 at 12:41 PM, Tightmopedman9 said:

Reduce your acceleration enrichment at low coolant temps, there is another accel enrichment table at 0xCFA4, same size and axes as the other tables. 

Also, reduce the values in afterstart enrichment at 0xD8B4, single axis table, 16 values long. 

It is impossible to get the 850 MAF to sit in the center of the 540i housing, it is off by more than .75". I stopped recommending this housing because it is a pain in the ALL GLORY TO THE HYPNOTOAD to tune. 

 

Avinit, I like the hole in your board so that you can solder the pins to the board in situ, very smart. 

My car idles rich if its completely cold on startup tats fine.

BUT it idles lean if I start it and it has not fully cooled off (Lets say coolant temp of 40C). I dont get it??? Do the warm-up maps not take dead times or injector constant into account?

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7 hours ago, Tightmopedman9 said:

Regarding the AC issue, I ran into this problem on a '97 850 once and through a XRAM dump I found F96F.4 was being set.  I believe this is an expected current draw too low error, but I can't find my notes from the diagnosis of the problem so I'm not sure. 

I removed the error check for this bit in the AC routine, and changed a few other bytes. Honestly, I'm not sure why I changed the other bytes, but I attached a screen shot of the differences made between the two .bins. The .bin on the left had functional AC, while the one on the right did not, and had the stock 608 AC routine. 

AC fix.jpg

I was comparing the 608 and my '97 850 binary the other day and wondered why the bytes above had been changed.  I started to disassemble the code a bit but haven't had the time to complete it yet.

Also have found some code dealing with the immobiliser so may have a play with that :-)

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Nopping  6AC6 and 6AC7  takes F96F.4  out of the equation in wich is determined wheter there is a fault situation in which the  AC shouldn't be activated.

 

7DE6, 7E7B, 7E7C and 7E84 are part of the logging routine and have nothing to do with the AC

 

Edited by Piet
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13 hours ago, Piet said:

Nopping  6AC6 and 6AC7  takes F96F.4  out of the equasian in wich is determined wheter there is a fault situation in which the  AC shouldn't be activated.

 

7DE6, 7E7B, 7E7C and 7E84 are part of the logging routine and have nothing to do with the AC

 

@Piet  So you're saying by making 6AC6 and 6AC7 NO-OPs (00) you're ignoring the AC fault TMM9 mentioned in his post here which he seems to be inferring indicates low current draw by the compressor was being detected; yes?

But how would/could it sense/detect compressor current draw unless the '97 GLT is wired up differently and/or has more ECU pins in play for the AC circuit that's been mentioned so far?

Do you know if B6 is an AI (analog input) or DI (digital input)?

Edited by gdog

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B6 is a digital input.

I think F96F.4 refers to a low Ac-pressure, in the DAMOS it's called: 

dpac_flag.4 MIN-Fehler (aktuell)

There's no way the ECU can measure current drawn by the compressor, at least not as far as I know.

Edited by Piet

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On 11/12/2018 at 6:42 PM, Piet said:

The AC routines of the '97 850 GLT are partially different from the 607/608 AC routines.

Amongst other things two RPM dependent lookup tables were added in the 607/608 bins.

I changed the AC routines of a  607 bin to match the AC-routines in the 97 850 GLT bin.

I think that will do the trick, but it has to tested when Chuck W is back in the US

 

 

Is that the routine that starts at 69E6 and is replaced by the code below?

75 A0 F8 78 71 E2 F5 2F 75 A0 F8 78 70 E2 F5 2E 
A2 00 72 7A 92 7A 75 A0 FC 78 B3 E2 F5 F0 75 A0 
F8 78 6F E2 20 7A 08 30 75 03 E4 80 08 60 06 25 
F0 50 02 74 FF F2 90 FC AB E0 A2 E2 92 76 90 C8 
FD E4 93 90 C9 3C B5 38 00 50 04 D2 70 80 09 94 
05 B5 38 00 40 02 C2 70 78 B9 E6 70 04 D2 71 80 
02 C2 71 30 7A 04 D2 72 80 08 30 72 05 30 75 02 
C2 72 78 6F E2 F5 F0 74 01 93 B5 F0 00 50 04 D2 
73 80 02 C2 73 74 02 93 B5 F0 00 50 06 D2 75 C2 
7A 80 02 C2 75 A2 73 A0 72 B0 70 82 71 B0 74 B0 
76 92 79 A2 07 72 78 92 78 40 02 80 1D 75 A0 F9 
78 70 E2 F5 F0 90 C9 3F E4 93 B5 F0 00 50 04 D2 
74 80 09 94 39 B5 F0 00 40 02 C2 74 90 E0 13 E0 
A2 79 92 E7 90 E0 14 F0 E5 2F 75 A0 F8 78 71 F2 
E5 2E 75 A0 F8 78 70 F2 22

 

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15 hours ago, Piet said:

B6 is a digital input.

I think F96F.4 refers to a low Ac-pressure, in the DAMOS it's called: 

dpac_flag.4 MIN-Fehler (aktuell)

There's no way the ECU can measure current drawn by the compressor, at least not as far as I know.

Hmm, this is not making sense then.  I still say something has got to be wired up differently then.  Like what B6 is sensing maybe?  B6 being a DI does limit the possibilities though.  Very interesting..

You got low AC pressure from that?  According to google it's current:

 

minErrCurrent.JPG

Edited by gdog

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Aha, haha, now I see where the "current" confusion is coming from.: google translate confusion :biggrin:

The german word for electrical current is "Strom"" (elektrischer Strom) not "aktuell" !!

 

Aktuell means current as in "at the moment"

 

No, it is ac pressure. ... In the same routine,  just before where the F96F.4  flag can be set, the AC-pressure is read with an ADC channel attached to B9

That's where I got it from.

 

Never trust Google translate !! :blink:

 

Something has got to be wired up differently .... sure.

However not in the ECU but in the AC-system itself.

Regretably I don't have a schematic of the Ac-system of an 97 850GLT

 

 

Edited by Piet

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Well, when I get back to the States at the end of next week, I'll try out your modified -608 bin, to see if it works.

The oddity with the AC function on the using the -608 bis modded with your original AC mod was the initial engagement of the AC compressor, then it stopping after 1 sec. This was only the FIRST time it was commanded after the battery was reconnected. After that, there was no AC function. So it's possible that the AC pressure flag was is getting set, and then that prevents the AC from running after that.

If it doesn't work, then I can investigate the external wiring, but seeing as there appears to actually be no schematic (or one that is easy to locate) for any differences that may be in the 97 GLT, AC wiring vs every other 96 and 97 850, I'll have to do some digging.

However, seeing as we now have a -936 bin and xdf, (Thanks to @Turboforslund !) and I have a spare -936 ECU, I can also just flash that and tune from there. 

I would like to be able to possibly figure out what the difference is, seeing as there appears to be no readily-available documentation regarding what that might be. Just to be able to better help the next person that encounters this.

 

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@Chuck W: I've emailed you a second version of a -607 with -936 AC routines incorporated.

Please delete the first version.

Edited by Piet

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Sorry for the confusion, I typed up that response hastily and didn't really pay attention to what I posted.

I was able to find my notes from the 'fix' and the problem was that the compressor would click on once, and immediately turn off, never to turn on again until the car was restarted. Maybe it was just a problem with their AC pressure sensor malfunctioning, but they did mention that they tested high and low side pressure when the problem was occurring and both were in spec. 

Probably disabling the pressure error shut off isn't the best course of action, but if you want to do so you can set 0xCAC6 & 0xCAC7 to 00. 

On 12/11/2018 at 1:26 PM, lowkeyturbo said:

My car idles rich if its completely cold on startup tats fine.

BUT it idles lean if I start it and it has not fully cooled off (Lets say coolant temp of 40C). I dont get it??? Do the warm-up maps not take dead times or injector constant into account?

It could be that you need to increase the cold start factor at higher coolant temps, while leaving the lower coolant temp values the same. 

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8 hours ago, Tightmopedman9 said:

Sorry for the confusion, I typed up that response hastily and didn't really pay attention to what I posted.

I was able to find my notes from the 'fix' and the problem was that the compressor would click on once, and immediately turn off, never to turn on again until the car was restarted. Maybe it was just a problem with their AC pressure sensor malfunctioning, but they did mention that they tested high and low side pressure when the problem was occurring and both were in spec. 

Probably disabling the pressure error shut off isn't the best course of action, but if you want to do so you can set 0xCAC6 & 0xCAC7 to 00. 

 

Well, I appreciate the follow-up. That is the exact problem here, and the AC works fine (and in spec) with the stock -936 ECU.


I'm not sure what changes Piet made in the bin he sent me, but I will FINALLY be home in the next couple of days to give it a try.

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I replaced the AC routines in a 607 bin with those of the 639-bin after having adjusted all parameters to those used in the 607 bin

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