Prom Codes

[vinsZR-1]

Thinking about purchasing a Haibeck chip
Whats the difference between 4168 AYBK and 8555 AUAH prom codes?
Vince
90 red/red #1966

[tccrab]

Thinking about purchasing a Haibeck chip
Whats the difference between 4168 AYBK and 8555 AUAH prom codes?
Vince
90 red/red #1966

I wouldn't worry too much about the difference between the two generations of firmware.
You CAN NOT go wrong with a Haibec Prom.
'Nuff said.

Things you won't miss:
CAGS
Elevated engine temps in around town driving
Fluctuating idle

Things you will love:
Rock solid 600 RPM idle
More top end pull (around 10 HP)
More TQ at bottom end
(I get loss of traction in 2nd gear just by mashing the go pedal)
Stable engine temps in traffic

Marc is a GREAT guy and a wealth of information.

TomC

[tomtom72]

The ABYK is just an update of the origional AUAH software that GM used to address some issues that 90 owners were complaining about. There was no recall issued, just a TSB on the symptoms customer's were/could complain about.

In the event of a customer complaint about hot idle fluctuation and or hot surging the TSB says to use ABYK as a service replacement to address the customer's complaints. If you would like to see the TSB is over at the netregistry site, in the "TSB & Recall" section.

:thumbsup:
Tom

[tpepmeie]

Make no mistake, the AYBK is a very different calibration than AUAH. AUAH was the second release production calibration circa 1989. AYBK was released nearly 4 years later and, like all the service cals, is substantially different. Mind you, I am not suggesting its better, or even noticeable, but it is different. Here are some of the changes:


change to Hot Restart spark retard
slight changes to low-load / idle spark advance
less MAT-based spark retard
new idle speed spark corrections (added correction for low idle speed)
more DFCO spark retard
tweaks to startup spark advance (and decay) values
ESC knock retard entry thresholds reduced
Added low octane spark retard logic
some new canister purge / integrator reset values
CARS (CAGS) barometric pressure criteria added
shift light disabled via temp threshold
Baro pressure read/update logic added. And a host of BARO checks to various functions in the program
minor tweak to crank fuel pulse width
less open loop MAP enrichment
various startup enrichment parameters changed
added new startup enrichment vs. MAT
Totally re-written / new Closed Loop fueling logic
warm restart fueling adjustment added
DFCO enable tps v. RPM added
vastly different Accel Enrich strategy (was TPS-based, now both TPS & MAP-based)
speed-based throttle follower offset added
various tweaks to better control IAC
new IAC keep alive memory function added
new IAC control added when in DFCO
new fuel trim factor vs. Baro pressure added
slight fuel table (VE) changesWhew! That about does it. It (along with the other "service" issue calibrations) are just simply a little more refined, complicated than the original issue ones. Not saying its better or worse. Engineers tweak anything when given enough time, and over 4 years they just got more sophisticated in the LT5 calibration approach.

Hope this helps.
Todd

[XfireZ51]

Make no mistake, the AYBK is a very different calibration than AUAH. AUAH was the second release production calibration circa 1989. AYBK was released nearly 4 years later and, like all the service cals, is substantially different. Mind you, I am not suggesting its better, or even noticeable, but it is different. Here are some of the changes:


change to Hot Restart spark retard
slight changes to low-load / idle spark advance
less MAT-based spark retard
new idle speed spark corrections (added correction for low idle speed)
more DFCO spark retard
tweaks to startup spark advance (and decay) values
ESC knock retard entry thresholds reduced
Added low octane spark retard logic
some new canister purge / integrator reset values
CARS (CAGS) barometric pressure criteria added
shift light disabled via temp threshold
Baro pressure read/update logic added. And a host of BARO checks to various functions in the program
minor tweak to crank fuel pulse width
less open loop MAP enrichment
various startup enrichment parameters changed
added new startup enrichment vs. MAT
Totally re-written / new Closed Loop fueling logic
warm restart fueling adjustment added
DFCO enable tps v. RPM added
vastly different Accel Enrich strategy (was TPS-based, now both TPS & MAP-based)
speed-based throttle follower offset added
various tweaks to better control IAC
new IAC keep alive memory function added
new IAC control added when in DFCO
new fuel trim factor vs. Baro pressure added
slight fuel table (VE) changesWhew! That about does it. It (along with the other "service" issue calibrations) are just simply a little more refined, complicated than the original issue ones. Not saying its better or worse. Engineers tweak anything when given enough time, and over 4 years they just got more sophisticated in the LT5 calibration approach.

Hope this helps.
Todd

Todd,

Would you indicate which of these are calibration mods as opposed to added /modded routines? I noticed that you show AE logic using both TPS and MAP. Are these tables? Is this unique to the AYBK or did it show up in a earlier def?

[tomtom72]

I stand corrected!:redface:

If you just read the TSB it just sounds like..."yea, if the owner complains, just put this in to make them happy!" :sign10:

I can say that the only things that I noticed was a lot more stable hot idle characteristics, a lot less rpm "hang" at de-accleration, and I thought maybe better hot restart behavior.:mrgreen:

:thumbsup: Todd!