Z31 - Wild switch at 141*F(60*C)

Nistune topics specific to the 6802 cpu

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harwood909
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Z31 - Wild switch at 141*F(60*C)

Postby harwood909 » Tue Jun 23, 2015 2:45 pm

I'll upload the log. It's short and sweet and illustrates what I'm experiencing when the ecu reaches 141 degrees F (60 degrees C). Injection time shoots up and goes very rich. I don't understand what could cause such a drastic change.

87 turbo Automatic computer (trans has been swapped to a manual)
Stock MAF
550cc injectors
o2 sensing is off
Attachments
140 switch_2015-06-02_0607_32.csv
(13.51 KiB) Downloaded 47 times

midian
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Re: Z31 - Wild switch at 141*F(60*C)

Postby midian » Tue Jun 23, 2015 4:03 pm

have you turned on "automatic transmission off" feedback switch?

harwood909
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Re: Z31 - Wild switch at 141*F(60*C)

Postby harwood909 » Wed Jun 24, 2015 11:00 am

Yes I have.

Matt
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Re: Z31 - Wild switch at 141*F(60*C)

Postby Matt » Thu Jun 25, 2015 12:32 pm

Post the tune file please. I see the jump 1.87ms to 2.77ms so the ECU code is doing something temp enrich related but not sure what

harwood909
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Re: Z31 - Wild switch at 141*F(60*C)

Postby harwood909 » Wed Jul 01, 2015 2:26 pm

Here it is Matt. The log I posted was not taken while running this tune but this tune had the same issue at 141F.
Attachments
6.26.2015 14.5psi stock maps.bin
(16 KiB) Downloaded 43 times

harwood909
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Re: Z31 - Wild switch at 141*F(60*C)

Postby harwood909 » Wed Jul 08, 2015 1:15 pm

Matt wrote:Post the tune file please. I see the jump 1.87ms to 2.77ms so the ECU code is doing something temp enrich related but not sure what


Any luck with this issue Matt?

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Re: Z31 - Wild switch at 141*F(60*C)

Postby Matt » Wed Jul 08, 2015 6:55 pm

Sorry I've got about 20 support cases to work through at the moment. This one required some intimate bench time with a Z31 ECU and your tune

Okay so 60 degC is the switchover point between batch injection and sequential injection

1.95ms both injectors are firing same time, after 60 degC it switches to 2.6ms and switching between one injector and the other

This is on the 21P11 base file, even stock tune does this and on the 21P01 image too. Standard ECU operation

If it is going to rich there may be a mismatch with the flow rate of your injectors (at a guess) causing this issue

harwood909
Posts: 9
Joined: Tue Jun 10, 2014 11:22 am

Re: Z31 - Wild switch at 141*F(60*C)

Postby harwood909 » Fri Jul 10, 2015 2:28 pm

Matt wrote:Sorry I've got about 20 support cases to work through at the moment. This one required some intimate bench time with a Z31 ECU and your tune

Okay so 60 degC is the switchover point between batch injection and sequential injection

1.95ms both injectors are firing same time, after 60 degC it switches to 2.6ms and switching between one injector and the other

This is on the 21P11 base file, even stock tune does this and on the 21P01 image too. Standard ECU operation

If it is going to rich there may be a mismatch with the flow rate of your injectors (at a guess) causing this issue



Ahhhhh this is making a little more sense now. There was a TSB for the fuel injection on z31. Part of the service was rewiring of the injectors so they are always batch fired. When I redid my harness I rewired them back to sequential. I did this because of the new injector connectors and to clean up the wiring.

I'm guessing the best thing to do would be to rewire the injectors so they will batch fire regardless of what the ecu is telling them to do. This is very confusing as to why they would program the ecu like this in the first place.

Mercennarius
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Re: Z31 - Wild switch at 141*F(60*C)

Postby Mercennarius » Wed Sep 30, 2015 3:01 am

harwood909 wrote:
Matt wrote:Sorry I've got about 20 support cases to work through at the moment. This one required some intimate bench time with a Z31 ECU and your tune

Okay so 60 degC is the switchover point between batch injection and sequential injection

1.95ms both injectors are firing same time, after 60 degC it switches to 2.6ms and switching between one injector and the other

This is on the 21P11 base file, even stock tune does this and on the 21P01 image too. Standard ECU operation

If it is going to rich there may be a mismatch with the flow rate of your injectors (at a guess) causing this issue



Ahhhhh this is making a little more sense now. There was a TSB for the fuel injection on z31. Part of the service was rewiring of the injectors so they are always batch fired. When I redid my harness I rewired them back to sequential. I did this because of the new injector connectors and to clean up the wiring.

I'm guessing the best thing to do would be to rewire the injectors so they will batch fire regardless of what the ecu is telling them to do. This is very confusing as to why they would program the ecu like this in the first place.


Did you ever rewire your injectors back and if so did it resolve your problem? Thanks.

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Re: Z31 - Wild switch at 141*F(60*C)

Postby Matt » Fri Jan 29, 2016 9:47 am

I've added parameters to the 1.2.55 version of Nistune yesterday

Attached is the Z31 address file (put in Documents\Nistune\Address folder) which contains the switch over temperature (60 degC) and a tickbox to enable disable

As for the switch over RPM/injection time this is a ratio which is hard coded into the ECU code

Code: Select all

9BDB : D6 54          ldab   RAM_0054_temp_mult
9BDD : 81 06          cmpa   #$06 <<<<<<<<<<<<<<<<<<< Switch to batch
9BDF : 22 1E          bhi   BRA_9BFF_Cranking
9BE1 : 25 04          bcs   L9BE7
9BE3 : C1 97          cmpb   #$97 <<<<<<<<<<<<<<<<<<< Switch to batch
9BE5 : 24 18          bcc   BRA_9BFF_Cranking

9BE7 : D6 1F          ldab   RAM_001F_Limit_Flag
9BE9 : C4 EF          andb   #$EF
9BEB : D7 1F          stab   RAM_001F_Limit_Flag
9BED : 96 76          ldaa   RAM_0076_inj_MSB
9BEF : D6 77          ldab   RAM_0077_inj_LSB
9BF1 : 20 1A          bra   L9C0D

9BF3 : D6 54          ldab   RAM_0054_temp_mult
9BF5 : 81 05          cmpa   #$05 <<<<<<<<<<<<<<<<<<<< Switch to sequential
9BF7 : 22 06          bhi   BRA_9BFF_Cranking
9BF9 : 25 EC          bcs   L9BE7
9BFB : C1 20          cmpb   #$20 <<<<<<<<<<<<<<<<<<<< Switch to sequential
9BFD : 25 E8          bcs   L9BE7


To add these parameters to the code will require another feature pack update

The 06/05 parameters on/off through testing move the RPM/injection time point (imagine a diagnonal line drawn through the fuel map).

We have found that resizing to large injectors (eg 1100CC as on my mates car) resulted in lower injection times and the switching point not happening until 6000rpm. Normally the stock ECU would switch over about 3000rpm

Adjusting from 06/05 to lower numbers like 04/03 seemed to help

The $97/$20 parameters also come into play here but I'm not sure how they are used at this stage but do affect the switching point
Attachments
Z31_VG30_128_E_88-89.adr
(2.31 KiB) Downloaded 33 times

harwood909
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Re: Z31 - Wild switch at 141*F(60*C)

Postby harwood909 » Sun Apr 17, 2016 3:11 am

I'm pulling the car out of storage today so I will tinker with it from a very... very cold start. :lol: I just updated Nistune as well to 1.2.57 and I see the check box and also the adjustment for the batch/sequential temp switch. So ready for summer after a solid 6 month long winter! Thank you

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Re: Z31 - Wild switch at 141*F(60*C)

Postby Matt » Tue Apr 19, 2016 12:48 am

No probs. I had to help a friend out his similar issues so hopefully this helps you too :)


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