I have had it with my 98s CPU and I need to know how to convert a 98Z28 to a later model CPU. Do I need to buy an aftermarket wiring harness? Or do I just need to set down and figure out the pin outs and modify them? Whatever would be the easiest way to do this.

 

repin the 98 harness to the 99 ecu pinout and swap to a 99+ coolant temp sensor. plug the repinned harness to the 99+ pcm and call it a day. the FAQ sticky has a several spreadsheets on how to do this.

 

The problem I'm having is with the CPUs control of the 4l60E's shift points. Is a 99 computer going to be fast enough?

 

Yes.. it should be as the 99+ are the same for M6 or A4's.. just pin'd and wired for the A4.

Also the Alternator is different. 98 uses Idiot light setup and 99+ uses PCM to excite the Alternator (not sure what is needed to change since I have a 99, but the FAQ and Sticky out line it). Carefull, if not done correctly, will blow the Alternator and you will have to replace.

 

Uhm.....Can you point me to the sticky....I went to the PCM tuning section and didn't see it.....I have a 98 LS1 and might want to use a 99 PCM as well....seems they are cheaper / more available...for some reason...

 

The Sticky or FAQ is at the top/start of the section, along with other threads.

https://ls1tech.com/forums/conversions-swaps/312119-ls1-swap-faqs.html

 

can i see one of these sticky's and spreadsheats I have been looking as well and cannot find them

 

The Sticky/FAQ are at the top of the "Conversions & Hybrids" Forum (or any of the forums if there are some) and are in Yellow. Open the Thread and then if there is a link (as there is for the PIN out of the PCM's) and follow the link(s).

What specify information are you looking for ? Pin out for the 98 vs 99 ? or are you looking for step by step information on what/how to do something? The information may or may not be in these Sticky/FAQ but are generally a good starting point to research or follow other threads/links.