so every time I try to get some help with my C4 86 everybody always says what kind of scan codes do you have. Well up until just recently I was not able to answer that question as I did not have the scanner. That is been remedied through 1320 electronics, I have their USB scanner, And now I have a whole bunch of codes or I should say scan data that I don't fully understand. I'm hoping that there is some intelligent bright Vetter out there that knows how to decode these very strange numbers. First of all as I pointed out this is on a 1986 C4 L 98 engine I have and 253,000 miles on the vehicle with a rebuild that took place according to the previous owner at 120,000 miles. How true that is I don't know. I've replaced almost all the sensors in the car since I got it as well as all the vacuum lines and if someone could let me know whether these numbers are good or bad while then I'll be styling
. These were all taken at idle at approximately 195 on the temperature gauge. all in open loop, if I take it out of open loop I get really strange readings. readings taken with ALDLdroid. And sorry for the long post I just wanted to make sure I got all the information in their. as always any help will be greatly appreciated

Tony

Engine speed= 975 to 1000

TPS= 55

CT 144.5 172 on the dash reading
CT 63 ( I don't know why there's two of them perhaps someone can explain that)

MAT= 140 to 230 this number bounces all over the place and does not stabilize on any particular number
MAT= 50-110 also all over the place, and don't know why I have second one

MAF = 7.48 Fairly stable reading

Injectors BPW= 159
INT= 129-134

BLM= 3

o2 812 at idle open loop
o2 x over= 160

IAC 30-32

 

So you're scanning 25 bytes at 160 baud in ALDL mode w-10 k resistor. So far so good, but you will find 160 baud is of little value. I'd say your *.adx file has some issues with incorrect offsets for some of the signals. Check your *.adx file.

Here's a list of the 25 bytes for reference starting with MW2 (which is not shown in the 160 baud list).:

Minor Lp mode word #2
;
; Bit 0 = 1= OVERDRIVE ON 0 = OVERDRIVE OFF
; 1 = ERR 14 or 15 THIS STARTUP
; 2 = REF PULSES OCCURRED (6.25 MSEC CHECK)
; 3 = 1= ALDL MODE, 8192 LOCKED IN, & MODE 4
;
; 4 = DIAGNOSTIC SWITCH IN DIAGNOSTIC POSITION
; 5 = DIAGNOSTIC SWITCH IN ALDL POSITION
; 6 = HIGH BAT. VOLT. , DISABLE SOLENOID DISCRETS
; 7 = SHIFT LIGHT (1= ON, 0= OFF)
;---------------------------------:

Note: this list does have some typos and errors here and there (I am not the author). I will try and edit to make corrections as I can. I've added some color to highlight signals of interest. Of those, I would consider the BLM to be of the most value, but the others are interesting as well.

**************************************** ***************
* 160 BAUD DIAGNOSTICS
* Table Of Addr's vs DATA
*
**************************************** ***************
ORG $070D
LC70D: FDB $C000 ; LOC 2, PROM ID (16 bits)
FDB $C001 ; LOC 3, MSB
FDB $002C ; LOC 4, IAC Present Posit.
FDB $005D ; LOC 5, Coolant temp, (A/D)
FDB $0065 ; LOC 6, Filtered MPH
FDB $0112 ; LOC 7, EGR D/C
FDB $0057 ; LOC 8, RPM
FDB $0081 ; LOC 9, TPS (A/D)
FDB $00C6 ; LOC 10, CORRCL
FDB $006F ; LOC 11, Filtered o2 Sig
FDB $0005 ; LOC 12, Err Flg #1,
;---------------------------------
; Bit 0 = ERR 23 MAT SENSOR LOW
; 1 = ERR 22 TPS LOW
; 2 = ERR 21 TPS HIGH
; 3 = ERR 16 NOT USED
;
; 4 = ERR 15 COOL SENSOR LOW TEMP.
; 5 = ERR 14 COOL SENSOR HIGH TEMP.
; 6 = ERR 13 O2 SENSOR
; 7 = ERR 12 NO REF PULSES
;---------------------------------
FDB $0006 ; LOC 13, Err Flg #2
;
; Bit 0 = ERR 35 NOT USED
; 1 = ERR 34 MAF SENSOR LOW
; 2 = ERR 33 MAF SENSOR HIGH
; 3 = ERR 32 EGR DIAG.
;
; 4 = ERR 31 NOT USED
; 5 = ERR 26 NOT USED
; 6 = ERR 25 MAT SENSOR HIGH
; 7 = ERR 24 VSS
;---------------------------------
FDB $0007 ; LOC 14, Err Flg #3
;
; Bit 0 = ERR 51 PROM ERROR
; 1 = ERR 46 VATS FAILED
; 2 = ERR 45 O2 SENSOR RICH
; 3 = ERR 44 O2 SENSOR LEAN
;
; 4 = ERR 43 ESC FAILURE
; 5 = ERR 42 EST ERROR
; 6 = ERR 41 CYL SELECT ERROR
; 7 = ERR 36 BURNOFF DIAG.
;---------------------------------
FDB $0008 ; L0C 15, Err Flg #4
;
; Bit 0 = ERR 63 NOT USED
; 1 = ERR 62 NOT USED
; 2 = ERR 61 NOT USED
; 3 = ERR 56 NOT USED
;
; 4 = ERR 55 NOT USED
; 5 = ERR 54 FUEL PUMP VOLTAGE
; 6 = ERR 53 OVER VOLTAGE
; 7 = ERR 52 CAL PAC MISSING
;---------------------------------
FDB $0044 ; 16, MWFA1
;
; 0 = NOT USED
; 1 = LEARN CONTROL FLAG (1= ENABLE STORE, 0= DISABLE)
; 2 = NOT USED
; 3 = NOT USED
;
; 4 = VSS FAILURE
; 5 = EECC SLOW O2 RICH/LEAN FLAG
; 6 = RICH/LEAN FLAG (1= RICH , 0= LEAN)
; 7 = CLOSED LOOP FLAG (1= C/L , 0= O/L)
;---------------------------------
FDB $0060 ; 17, MAT
FDB $0037 ; 18, MCUINST
;
; Bit 0 = PARK/NEUTRAL MODE
; 1 = NOT IN THIRD GEAR
; 2 = OVERDRIVE REQUEST
; 3 = EXCESSIVE POWER STEER PRES., CLUTCH ANTICIPATE
;
; 4 = EGR DIAGNOSTIC SWITCH CLOSED
; 5 = TCC LOCKED
; 6 = FAN REQUEST BIT
; 7 = 0 = A/C REQUEST
;---------------------------------
FDB $00A1 ; 19, OLDPA3 Counter
FDB $00C0 ; 20, BLM
FDB $00F1 ; 21, ALDLCNTR
FDB $00EA ; 22, MAF gm/sec, (16 bits)
FDB $00EB ; 23, LSB
FDB $00D5 ; 24, Base PW (Last Inj), (16 bits)
FDB $00D6 ; 25, LSB
**************************************** ***************

 

Once scanning, you can try switching off the 10 k resistor to see if you can still scan and if your idle will return to normal instead of 1,000 rpm in ALDL mode. I never tried this since I use 8192 baud whenever possible, but its worth a shot and easy enough to test.

 

Thank you so much for the reply TB. As far as the file I used, I used the one that came with aldldroid for an 86 L98 motor. This is still VERY new to me and all help is so appreciated.
To answer your ? about the 10k resister. If I switch it off the readings are erratic or not even available. Can you please enlighten me if there is a better way to scan my 86. Or do you suggest a different file.
I'm sorry but the additional numbers that you sent are greek to me. I'm still in learning mode and dont mind being held by the hand till I learn all this stuff. A better explanation of this would help a lot. Consider the fact that I know diddly squat about this.

Tony

 

On second thought, scanning without the 10 k resistor should just return the 5 bytes that go to the dash, so this won't help much.

8192 baud scanning is the way to go, however this can be problematic with 1986 cars, more specifically 1986 $32 mask bin files.

Today, the easy solution is to use DataCat. In the old days, Diacom has been reported to work at 8192 baud for 86 cars.

I've re-written some 86 bins to be more scan friendly for use with TunerPro, but I've never been able to get TunerPro to connect at 8192 baud with a "normal" 1986 bin, no matter how hard I've tried messing with the adx file (handshake).

Running a later 87-88 or 89 bin can make sense in some cases, especially for auto trans cars, but 4+3 cars should stick with 4+3 bins of the correct vintage, unless you really know what you're doing.

I've posted some adx files both for 160 baud ALDL Mode and 160 baud dash data in the past, if you do some digging.

If somebody has an adx file out there that will connect to a 1986 bin and allow scanning at 8192 baud, I would love to see it.

Regarding the 25 byte list that I provided, what is important to note is the variable name, location and offset (offset = (location -1)) of each byte within the datastream from 1-25 commented as LOC *. The first byte is MW2 (offset = 0), the 2nd and 3rd bytes are the prom id (offset = 1), 4th byte is the IAC (offset = 3), and so on as shown in the list.

The adx file needs to have the correct offset and conversion scaling in order to make sense of each signal and to display it properly.

Since there is no INT in the datastream and the BLM of 3 is obviously wrong, your *.adx file has some issues as you've already noted with some wacky looking values or what appear to be duplicates of some signals.