[V8] V8 Digest, Vol 93, Issue 9

[Mark Hanman]

>    1. Re: ABT chip (Scott Justusson)
> 
>  The ABT PT chip is still available, as that programming has been well copied over the years.  Scott P advertised them for sale recently, and the other common Audi chip sources stateside have them as well.   I have one of the rare ABT ABH chipped boxes installed in my 92 auto, but I've never really had interest in copying it.  Yes, they are meant to be run best with modified camshafts.  That said, all of the gains from a non-cammed car will come in the timing tables.  Ideally, the best way to install the ABT chip is with an adjustable fuel pressure regulator, as the fuel tables are tweeked as well, and without the regulator, the car will suck a lot of fuel that was meant to feed those cams.  I have supplied several sets of custom modified camshafts years ago for both the 3.6 and the 4.2, and with the modified chip the difference was significant.    
> 
> The approach some have made, is to use the PT engine harness with 3.6 ABT chip to run the 4.2 engine.  It 'can' work, but IMO, it's a first class step backwards (hack).  The ABH wiring, programming and sequential injection is many factors more advanced than the PT computer.  So much so, that I doubt there is much difference in the Horsepower running the ABT PT computer on a 4.2 car, then just running a stock 4.2 computer.
> 
> HTH
> 
> Scott J
> 92 v8 ABT Chipped
> 

I've watched this discussion gather pace, and it's slowly getting emotive for what I believe are a few misunderstandings.
I am running a 4.2ABH engine in my silver 1990 car. The original 3.6PT was badly damaged by poor maintenance and repair previously.  SO I needed an engine.  And replacing like for like is difficult over here anyway.  The 4.2ABH came from a complete car that I bought, but was too badly damaged to be financially viable to repair.  It was a nice machine to drive as an original 4.2ABH, though.
These are my (subjective) thoughts on the evolution of my silver car.As a 3.6, the car was nice to drive, but no major performance machine.With the 4.2 running on the standard 3.6 harness, it was a big improvement.  Mainly in low down pulling ability.With the ABT chip fitted, there was a serious improvement over even this. The car is serious fun to drive (and has embarrassed a few noisy little hatchbacks).  So much so, that I am arranging to have some fairly major renovation work carried out, as this car is a keeper.
Sadly, I never had the opportunity to test out the ABT chip in a standard 3.6 at that time, so there is a stage of subjective evaluation missing. until now.  I now have a 1991 black 3.6.  Before I start chipping it, though, it needs some major efforts to get it running right. it's a V7 at present, among other awkward running issues.  Once it is running properly, then it shall be chipped.  And then I shall know for sure.
I can understand Scott J's comment about the backwards step thing.ABT chip + 3.6 electronics + 4.2 engine is a backwards step from the refinements and capabilities of an original 4.2 setup.But ABT chips cannot be found easily or even at all, for the 4.2.  So, unless the chip is made available by some enterprising and benevolent soul, much will remain the same.However.  When I stripped the dead 4.2 car, I kept the wiring, boxes, etc.  With the future hope of obtaining the 4.2 version of the chip.  How much work is required to do this nicely?  I lost a lot of blood getting the wiring out of the stripped car, so putting it back into a running car is no small task.  And there are a number of questions that need clarifying, regarding the interaction of the ECU and TCU, before I go ahead.
Some of Scott J's other comments give pause for thought, though.When I did the initial 4.2 engine swap, I did this as a complete unit, with all the sensors and fuel rail still in place.  The car ran great, but it was obviously over fuelling. From Scotts comments, it would appear sensible to accept that this is due to the fuelling characteristics/requirements of uprated cams.  Which i do not have.Swapping to the injectors for the 3.6 made the fuelling issue much better.  Since then, I have stumbled across a comment in the audi maintenance manual, regarding the injectors, stating that they are not interchangeable.  It doesn't clarify whether this is simply due to flow, or if there are more fundamental reasons for this.I have much to learn, yet, about this car.  I'm still more attuned to the 10v turbo quattro.