More TPI questions

John Hess JohnH at ixc-comm.net
Fri Jan 17 15:55:10 GMT 1997


Many of the tuners don't really recognize the existence of the '85. 
 The major difference is the use of a different ECU and harness and 
the addition of VATS with the '86 model year (from the '86-89).  There 
are other changes; but, these one significant in that the ALDL data 
rate is 160 bpS rather than the 8192 of the later ECUs.  This may 
sound insignificant until you try to take real-time readings of the 
engine parameters for performance mapping purposes.



----------
From:  Jeffrey R Muehl[SMTP:JRMUEHL at mail.delcoelect.com]
Sent:  Friday, January 17, 1997 7:22 AM
To:  diy_efi at coulomb.eng.ohio-state.edu
Subject:  RE: More TPI questions









Many of the aftermarket people don't even treat the '85 as a TPI in 
their discussions.  To start with, it uses a computer (ECU) unique to 
the model year.  Trying to get information on that particular 
computer/assembly are largely fruitless.  From what I understand (and 
I am not certain that I understand everything I know about the 
subject), you start with a different ECU, no pre-cats, VATS added in 
'86, and different ALDL data rate.  There may (probably are) more 
changes;  but, this is all I have heard about.

Ok, here we go...

>What is the difference between the 85 vs. 89 system.
>>
>> Too numerous to describe.  It was the first generation TPI system
>> and
>> was significantly changed for '86.  The '86 through 89 is pretty
>> consistent (some mapping and other variances to basically the same
>> system)

It was stated that the 85 -vs- 89 differences were "numerous".
Were these differences just in the ECM or were sensors, TB, etc 
changed?
I want to convert an 85 system to the 89 ECM.  What's involved?
If it's just a harness conversion, I'm not worried.

>Ok - lets say that I have an '87 TPI - basically stock.  Can I
>just swap out a PROM for the '89 TPI to eliminate the cold-start
>injector
>on my '87??  IOW, is there a hardware(wire harness) difference
>that would prevent this (other than the cold-start injector wiring)

Any help would be greatly appreciated!

Jeff







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