i'm swapping the 305 TBI out of my '91 camaro for an '88 gta 350 tpi. Will the 305 wiring harness work with the 350 if i swap out the PCM, or do i have to pull the harness out of the donor car? moreover, will i have to use the digital dash from the GTA? i hate those friggin' things.... any knowledgeable help would be hugely appreciated.

 

You absolutely have to take the donor harness because a tbi is completely different from TPI. Then you need to research your pinouts for the C100 and C207 connectors to see how they are different. Its easiest to just swap all the wiring between cars. There is far too much information on swaps such as these you really need to

 

88 L98 will be MAF style where the 91 camaro will be expecting SD. Quite a few pins need to change

Snoop the LTx/LSx forum for the pinouts for both years and decide which pins need to change

 

TBI only has injector wiring for 2 injectors that fire together, TPI uses 8 injectors firing at different times - so for that reason alone you'll need a TPI harness and chip. Not to mention that TBI uses a MAP sensor but TPI uses MAF or SD. Also TPI uses coolant temp readings where TBI doesn't even capture those readings. So yep, definitely need a TPI harness if doing TPI.

 

fantastic!! this is my first project so i'm gonna be on here asking a whole ton of questions i'm sure. for my first thread u guys have been great so far, i apppreciate it a ton.

 

Ignore all that

TPI is batch fired just like TBI. Sequential injection firing each injector one at a time didnt come around until 94 for F-bodys
Look for yourself
TPI
http://www.austinthirdgen.org/mkport..._injectors.jpg
TBI
http://www.austinthirdgen.org/mkport..._injectors.jpg

Mighty similar yes?

88-92 TBI and 90-92 TPI are all SD. No either or MAF/SD setups exist for 3rd gens, you have one or the other. Redundant systems like that didnt come about until 94 with the LT1 and wasnt perfected until 98 for the LS1. Those rely heavily on the MAF input with the MAP sensor as a backup but can be tuned to rely solely on the MAP. You just cant do that with any of the 3rd gen ECMs

TBI and TPIs both use CTS' from the ECM and pay close attention to them. In fact, TBIs are very picky about the CTS as bad ones cause owners lots of grief with excessive rich conditions
TBI
http://www.austinthirdgen.org/mkport...ta_sensors.jpg
TPI
http://www.austinthirdgen.org/mkport...ta_sensors.jpg

I cant think of any GM EFI engines that dont use a CTS