tbi to tpi

[EFISYSTEMS at aol.com]

Hi,
    I could be completely wrong with this, but I have done swaps like this in 
the past with no problems.....Ludis,Terry and others might have some more 
insight on this.......yes the signal from the vss is diff...but all the 730 
cares is: has tps lowered and has vss lowered....therefore decel 
enleanment...you will have to play with some of  the mph and tps stuff in 
your 730 chip but you can make it work......pulses per mile is the area that 
needs to be changed for correct lockup of the torque convertor....,,,,,,,if I 
am missing something guys I would love the feedback. hth's
-Carl Summers

In a message dated 8/4/99 12:18:32 PM Pacific Daylight Time, 
DIY_EFI-Digest-Owner at efi332.eng.ohio-state.edu writes:

<< 
 Date: Tue, 03 Aug 1999 14:12:45 PDT
 From: "David Sagers" <dls2867 at hotmail.com>
 Subject: TBI to Port Injection
 
 I ran into a brick wall with my DIY EFI project this morning.  I'm 
 converting a '92 Suburban TBI to a '90 TPI MAP system.  I have about all the 
 parts including the TPI system, brackets, cables, etc...
 
 Called this morning to buy the wiring harness and the tech at Painless 
 Wiring said that I was headed for a big problem.  The speed sensor in the 
 Sub runs the speedometer and something to do with the brakes.  He said the 
 problem is that the TPI ECM uses a different speed sensor than the TBI uses. 
   And they are vastly different in the signals they produce, are not 
 interchangeable, nor can you run a dual sensor system.
 
 I remember seeing in a Jegs catalogue that Edelbrock sells a multi-port 
 system that uses the the TBI computer but requires Edelbrock's chip to make 
 this work.  I called Edelbrock and they do not sell this chip separately, 
 only with the full EFI set up.
 
 The Edelbrock system was a possibility until; 1) the tech said that his 
 system is not big enough to feed the 400 SBC I have ready to go in the 
 truck.  The injectors are only 19 lbs/hr;  2)and the tech said that the cam 
 I using would require a custom chip anyway.  I may have given him the wrong 
 specs on the cam because I bought a mild towing cam for the Suburban; 3) 
 I've already paid for all the TPI stuff and really like the long runners on 
 the TPI, not sure I can really afford to shell out another $1000 for 
 Edelbrock system.
 
 Some where in the box with the TPI stuff is a harness adapter that is 
 suppose to convert the TBI injector harness to an eight injector harness for 
 the TPI.
 
 But the big question.  Does anyone know of a chip maker that makes a chip 
 that will allow my TBI computer run a TPI system?
 
 
  >>