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]

Originally Posted by vinszr1

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.


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) changes

Whew! 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]

Originally Posted by 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) changes

Whew! 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!

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

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.

Todd!