E129: is an address relative to the origin at C000.

This is the same as address 0x2129 expressed in raw hex form.

14 36 01 is simply the assembly code representation for BSET L0036,#$01 (expressed in hex bytes).

You should see the same 3 bytes starting at address: 0x2129 if viewing the bin with a hex editor.

15 36 01 is the suggested fix (again expressed in hex bytes): BCLR L0036,#$01.

To summarize: Change the 14 to 15 and save the bin with your editor again to recalculate the checksum.

After some thought, a cleaner and more efficient approach is to simply clear bit 0 instead of setting bit 0.

Just replace the line:

E129: 14 36 01 BSET L0036,#$01

with:

E129: 15 36 01 BCLR L0036,#$01

Somebody with an auto trans should evaluate to ensure correct TCC function and no interference from CAGS.

Sequence of test changes:

First change was to replace the ADNA #$FB with ANDA #$FA to clear both bit 0 and bit 2.

CCB1: ANDA #$FB ; CLR b2, (DRP LAST 6.25 Ms)

This resulted in toggling of the OD indicator, so I knew I had the correct bit.

Next step was to eliminate the statement where bit 0 was likely being set:

E129: BSET L0036,#$01

This was done by inserting NOPs to replace the BSET L0036,#$01.

The OD indicator stayed off with these changes during my limited testing.

Tonight I confirmed that Bit 0 of $0036 is what controls the OD indicator when running $6E software in an 87-88 car.

; b0 1 = CARS ACTIVE

In $32B software this is $0035 bit 0:

; Bit 0 = 1= OVERDRIVE ON
; 0= OVERDRIVE OFF

I mistakenly called it bit 1 in my previous post but really meant bit 0. Sorry for any confusion.

My first attemt at clearing bit 0 resulted in a toggling of the OD indicator, so I knew I had the right bit this time around.

The fix requires preventing the bit from being set as part of the CARS (CAGS) logic in $6E.

Not really difficult to do, but it can be set in a couple of spots.

I was a bit suprised that the dash uses 8192 baud data, but the shift light was a clue, since this is only present in the 8192 baud data stream.

You learn something new everyday, I guess.

First test failed. Bit 5 clears as expected with changes, but OD indicator still on. Must be another bit...

Current thinking is that $0036 bit 1 is controlling the OD indicator, and bit 7 is controlling shift light. Still need to verify.

C6D9: FDB $0036 ; 54, MODE WORD 2
; b0 1 = CARS ACTIVE
; b1 1 = MALF 14 OR 15 THIS START UP
; b2 1 = REFERENCE PULSE OCCURRED
; b3 1 = IN ALDL MODE 8192 LOCKED IN AND MODE 4
; b4 1 = DIAGNOSTIC SWITCH IN DIAG POSITION
; b5 1 = DIAGNOSTIC SWITCH IN ALDL POSITION
; b6 1 = HIGH BATTERY VOLTAGE-DISABLE MCU SOL DISABLE
; b7 1 = SHIFT LIGHT ON
;
;-----------------------------

I think I found an opportune place to clear bit 5:

By changing the ANDA #$F7 below to ANDA #$D7 at address CB5E, this should clear both bit 3 and bit 5. Only needs to execute once. Bit 5 should never be set by code.

I'll give it a shot and see what happens.

Excerpt from $6E source hac:

;----------------------
; CK AFR MODE WD
;
;----------------------
CB47: LDX #$C014 ; INDEX AFR MODE WD'S
CB4A: BRSET 2,X,#$04,LCB54 ; BR IF b2, MW3

CB4E: BRCLR 0,X,#$04,LCB54 ; BR IF NOT b2, ANALOG MAF IN USE
; ... else
CB52: EORA #$04 ; If so Invert Bit 2

CB54: LCB54 BRCLR 3,X,#$20,LCB5A ; BR IF NOT b5, MW4 (N.O. FAN)
; ... else
CB58: EORA #$40 ; If so Invert Bit 6
CB5A: LCB5A BRSET 3,X,#$40,LCB60 ; BR IF b6, MD4
; ... else
CB5E: ANDA #$F7 ; CLR b3, PWR STEER
CB60: LCB60 STAA L0038
;-----------------------------------------------

I suspect that the OD indicator in the 87-88 specific cluster is controlled via serial data rather than a hardwired pin.

Edit:
Got abit ahead of myself. Same idea, different bit. Must be in the 160 baud data stream. TCC bit 5 seems to fit the bill.

$32B data:
LC7CD FDB $0037 ; 55 MCU INPUT STATUS WORD
;
; Bit 0 = PARK/NEUTRAL MODE
; 1 = NOT IN THIRD GEAR
; 2 = OVERDRIVE REQUEST
; 3 = EXCESSIVE POWER STEER PRES. , CLUTCH ANTICIPTE
; 4 = EGR DIAGNOSTIC SWITCH CLOSED
; 5 = TCC LOCKED
; 6 = FAN REQUEST BIT
; 7 = 0= A/C REQUEST
;---------------------------------

Equivalent $6E data:

FDB $0038 ; 18. MCU STATUS FLG
; b0 1 = IN PARK/NEUTRAL
; b1 1 = NOT IN THIRD GEAR
; b2 1 = OVERDRIVE REQUEST
; b3 1 = EXCESSIVE POWER STEERING PRESSURE
; b4 1 = EGR DIAGNOSTIC SWITCH CLOSED
; b5 not used - OMITTED FROM S/W (1 = TCC LOCKED)
; b6 1 = FAN REQUEST BIT
; b7 0 = A/C REQUEST
;---------------------------------

Note: When I run a $6E bin in my 88, I see that bit 5 is always set when scanning. Scanning also interferes with the OD indicator, so it would need to be tested with and without scanning to confirm that the lamp and bit are related to each other.

Need to find where bit 5 is set in $6E and prevent or force it to be cleared. Will look into later.

Then you need to determine if there are any adverse effects.

I've always wanted to get to the bottom of this issue, so I may test it myself, if I get around to it.

I gotta figure something fishy with how the external ESC module is wired, that is preventing or interfering with the distributor reference pulses.

Scratch that, I recall Mick feeling compression when checking #1 for tdc.

Here's a thought.

Stock chip (86 $32 mask) does not require reference pulses to fire injectors during cranking.

89 based chip ($6E mask) requires 8 reference pulses before firing injectors during crank for cleaner cold start emissions.

This can be edited in the bin.

;----------------------------------------------
; CRANK FUEL PW MULT Vs. REF PULSE LT 17
;
; 10-18-1997 Dissassemby of ARAP Lines= 16
;
; TBL = 256 * MULT
;---------------------------------------------
ORG $038B ; MULT DRP'S
;---------------------------------
LC38B FCB 0 ; 0.000 1
LC38C FCB 0 ; 0.000 2
LC38D FCB 0 ; 0.000 3
LC38E FCB 0 ; 0.000 4
LC38F FCB 0 ; 0.000 5
LC390 FCB 0 ; 0.000 6
LC391 FCB 0 ; 0.000 7
LC392 FCB 0 ; 0.000 8
LC393 FCB 128 ; 0.500 9
LC394 FCB 128 ; 0.500 10
LC395 FCB 64 ; 0.250 11
LC396 FCB 64 ; 0.250 12
LC397 FCB 64 ; 0.250 13
LC398 FCB 64 ; 0.250 14
LC399 FCB 64 ; 0.250 15
LC39A FCB 64 ; 0.250 16
;---------------------------------------------

Sounds to me like valves are hanging open. No compression.

With the HPX sensor, I'm simply doubling the range to 510 gm/sec now. With my own car, I'm seeing airflow peaks around 430-440 gm/sec and targetting 11.8 AFR in PE.

An example Vortech Si-trim with a 3" pulley on an otherwise stock L98 is flowing around 370 gm/sec at 5,400 rpm with the same sensor with a 260F discharge temperature.

Here's a pic:
[IMG]http://i15.photobucket.com/albums/a372/tequilaboy/07-18-09_1804.jpg[/IMG]

I would intend to run the same size tire all around.

I measured a 255/60R17 General Grabber UHP mounted on a Toureg. From the specs, this is also supposed to be 29" tire like the 275/55R17. Actual height was about 28 1/4" tall, so I suspect that the 275/55R17 is closer to 28" than 29" FWIW.

I would also consider a 255/50R17 front and 275/55R17 rear combination.

With my 3.73 gears, the 255/50R17 will behave like a 3.55 gear, the 275/55R17 or 255/60R17 would behave like a 3.37 gear, compared with my present 255/45R17 tires.

I wouldn't mind the shorter effective gearing. Its good to see that there are some "different" options available.

Mick's car looks pretty good with 28" M&H 325/45R17s, so it would appear that 28" tires will work/fit.

How about a 29" tire? I've been considering some 275/55R17s lately, but will likely go to a 27" tall 255/50R17 instead, next time I need tires.

For a 17x11 wheel there aren't too many choices. Check out the M/T 295/45R17 ET Street Radial II if you're looking for a Drag Radial, or the aforementioned M&H.

It would be nice if there were a few street tires in these approximate sizes. 17x11 wheels have limited choices for tires.

Hey Mick,

I've been using Hawk HP+ pads on 12" rotors since last spring. They do dust and squeal a little, but they are effective. They may be a bit abrasive when cold, but no issues with the friction.

I'm not sure how long they will last, but I intend to buy another set.

The tube configuration, air and egr fittings look like my LPE 1 5/8" long tubes.

These tubes are definitely larger than mine and the collectors also appear to be a bit different which makes sense given the larger tube diameter. My collectors step down from 3" to 2 1/2" for the LPE supplied slip fit y-pipe, intended for the L98 main cat.

Its hard to tell if these have the same step down 2 1/2" collector, since the slip fit y-pipe is in place, but its likely that they do.

I'd say that they appear to be old LPE 1 3/4" Long tubes.

I know there are some ceramic coated impellers intended to improve efficiency mostly used for turbos. I don't know how effective they really are for centrifugal superchargers, though. Less friction with the air maybe, I think the Raptor uses one.

Coating the volute/diffuser may keep the components themselves cooler, but I think that would just tend to increase the charge air temperature.

I'd really like to see somebody do a fully shrouded impeller like the old DVL design. That's supposed to be the most efficient impeller style. Basically an impeller with a cover on top of the vanes which avoids any leakage between the vanes and the case. Would be expensive.

Not directly on topic, but here's an interesting read on overlap and scavenging with inlet pressure greater than exhaust pressure. (I love these old NACA reports):

http://www.not2fast.com/NACA/naca-tn-405.pdf

and another (more interesting):

http://www.not2fast.com/NACA/naca-tn-2025.pdf

With forced induction, the only concern is to minimize backpressure at acceptable sound levels, and to keep the flames from setting things on fire.

The intake pressure and overlap will scavenge the cylinder just fine once your into boost. My guess is that you're into boost before the headers would have any effect.

I suspect its what's downstream that has more effect on the back-pressure than the primary tube diameter, but I agree that bigger should be better.

Another interested party.