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Discussion Starter #1
Hello! I recently bought an 8051 pcm from a 95 caprice for my 96 so I can tune it. I want to do the resistor mod myself but after looking everywhere, all I found was mentions of it and broken links but not how to do it.
I was wondering if someone could tell me pins I need to join and what kind of resistor I need and where that goes.

Happy New Year!
 

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Discussion Starter #2
Finally found it (after 2 hours). Sorry to waste your time. Connect pin 22 to 21 in the blue connector, and connect either one to ground with a 2k ohm resistor.
 

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Discussion Starter #3
Thanks Cappy p!
Still kinda new here, forgot about the pm's
 

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Discussion Starter #5
Now I'm confused, do I still have to join the two knock sensor circuits together if I use a 3.9k ohm resistor to ground?

 

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First until I find my documentation, I wont comment on resistor values.

The 95 F body only had one sensor so you have to use F body forum info carefully.

As shown in the pictures I posted, the 96 B body has the 2 sensors separated in the harness on pin 21 and 22

To make a 96 B body harness and sensors with a 94-95 PCM ACT THE SAME AS a 95 B body car,

21 and 22 must be connected , and have a resistor to ground.

This so the two 96 sensors together, have the same resistance as two 95 ( factory tied together) sensors do.

I guess a person could not connect the 21-22 , use the resistor the F body guys use and only have the one knock sensor operating, but why ?
It is there, why not use it .

Gerry
 

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I guess a person could not connect the 21-22 , use the resistor the F body guys use and only have the one knock sensor operating, but why ?
It is there, why not use it .
Gerry
Why not just install the correct knock sensor?
Like microphones and speakers the resistance is only part of their specification. The best result will be with the correct part. Both 94 and 96 knock sensors are available new.
 

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Because, the idea is to make the PCM drop in.
As in you could swap back and forth

As I have the ability to tune a 1996-97 LT1 I would not have to do this. .

The one time I did, it was before there was an affordable option ( which is now gone )
It was on a guys Buick that had a gear change .
He needed to plug in the 96 PCM for his yearly test.
Not here to argue the merits or reasons for the swap, just trying to help answer the "how to do it : question

I do not have back to back comparisons but seem to remember the knock sensors operating just fine.
Think the resistance mod is more for testing and blowing codes.
Case in point, you can put a F cal that was based on one Knock sensor in a B car with two parallel Knock sensors with no issues. ( other than EVAP temp )
Used to be very common place with a manual trans swap before more tables were opened up in TC
 

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Discussion Starter #9
Thanks 95wagon! Didn't know the f body's only had one ks, that explains alot.
I whould very much like to be able to easily change between 95 and 96 PCMs for emissions, reading codes,ect.
 

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Discussion Starter #10
If the f body PCM needs a 3.9k ohm resistor and it only has one KS, than whould a b body PCM need a 2k ohm resistor because it has two?
 

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Discussion Starter #11
Can pin C13 "performance mode switch signal" be used?
 

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If the f body PCM needs a 3.9k ohm resistor and it only has one KS, than whould a b body PCM need a 2k ohm resistor because it has two?
Still cant find my notes but these two posts suggest the number is 2.2K but 2K works
.https://www.impalassforum.com/threads/obd1-resistor.1192065/
 

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Can pin C13 "performance mode switch signal" be used?
IIRC you need the F-body bin to have it function, although the table still appears in tuning software.
Many posts on here, just search "performance mode" in this subforum.

Hope this helps -

Jim
 

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For all our sakes, let it be known, that an F-car .bin file is not needed to use Perf Mode.
Besides, our air conditioning and radiator cooling (among other things) work slightly differently than F- or Y-cars.
B- & D- cars should use B- or D-car .bin files.
 

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For all our sakes, let it be known, that an F-car .bin file is not needed to use Perf Mode.
Do tell,
I was under the misconception that perf mod was not enabled in the B car cal although the tables are there.
BUT I HAVE NEVER DONE IT so am just regurgitating info.
I see in Tunercat OBD2 there is a switch but don't see it in Tunercat OBD1 but I realise that in itself doesn't mean it does or does not work.
Is there a switch in other programs .
Marky Dissod, you have personally set up Perf Mode working in a B cal?

Besides, our air conditioning and radiator cooling (among other things) work slightly differently than F- or Y-cars.
B- & D- cars should use B- or D-car .bin files.
Not suggesting it is for everyone, but not a "the sky is falling " senario
Back before the rev lockout switch was added to the options in Tunercat OBD , it was the only way to get the reb lock out to work like factory in a stick conversion.
As for the ac difference, setting the two Evap tables to 0 , matching the B car tables is all it takes to "fix" the AC issue
What other issues have you found with an F cal based cal in a Caprice or Impala?
 

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In OBD1 LT1, assuming you have the wiring needed, you can either have Performance Mode, OR you can have 2nd Gear Start.
From what little experience I have, one excludes the other.

Since I've very little experience with F- or Y-cars (the few B-cars in the 5 boros outnumber F- & Y-cars combined), only issues I've ever had were trying to operate a B-car with an F- or Y-car .bin file, where the Roadmaster AC basically downgraded itself to Caprice AC.
 

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Here is a copy of Scott Mueller's write up for a F calibrated PCM.


For the record I tested my stock 94 b body PCM and it did not respond. Some forum members say it will work.

If some one who has actually reprogrammed a 94-95 b body PCM to use the switch would explain how the mystery would be solved. I am not wanting to start with a F calibration
 

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Mueller said
" If you are not running a '94-'95 F-car PCM, then you will want to talk to your favorite PCM reprogrammer to have the performance shift subroutine installed in your PCM"


Subroutine, is that techno speak for slapping a B serial on an F cal and locking the user out ?? jk ;)

Personal opinion , I never pursued it when I had an auto because I felt if there is only one person driving the car, all the shift points, firmness , etc vs throttle, RPM, speed , can be set for most all conditions.
I tinkered with mine for months , fine tuning to my likes and requirements.
Now, if i had a big trailer or something, I might sing a different tune.
 

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1. Scott Mueller did not know that the 16181333 & 16188051 pcms are functionally identical; there is no (dis)advantage to either pcm, regardless of vehicle of origin.
They will accept any B- D- F- or Y-car .bin file and - assuming no internal circuitry faults - should work and run no better or worse than another random -1333 or -8051.

2. Any B- or D- car .bin file can have its 'Performance Mode' functionality enabled ONLY by DISabling the 'Force Manual Mode in D2' flag / switch.
2a. With the 'Force Manual Mode in D2' flag / switch DISabled, all that's left is the wiring and switch hardware.

3. 95wagon, I mostly agree: one shift table is enough for nearly everyone, especially when customised by its main driver, unless towing / hauling very heavy loads.

Unsure why GM let Cadillac Fleetwoods V4P miss a gas-guzzler tax by 0.1MpG with only one usable shift table, instead of letting drivers pick from 2 shift tables.
 
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Thanks MD for supplying a answer. I had given up on the Performance Mode as I got my transmission to shift as I wanted it to. As I really do use the B4U to tow this will save me flashing a different tune for the heavy hauls.

The real advantage is you can compare two different shift tables on the same test drive. Much better than test reflash test cycles.

I thought GM referred to PCM updates as "calibrations"

Your information should be moved to a new thread then made a "sticky"
 
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