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84 SVO vs 86 XR4ti EEC comparison



I just got done comparing the differences between the EEC-IV wiring of the
84 Mustang SVO and the 86 XR4ti. Note that the 85.5 to 86 SVO is very
different than the 84 to 85.5 SVO.  The later model is probably much closer
to the XRs wiring, although the data tables would still be different.  This
document ALWAYS refers to the 84 SVO, not the later one.

Why would I want to do this?  I want to put 36 lb hr injectors in my SVO,
and I have the head, turbo, intake, injectors, and EEC-IV module from an 86
XR.  The early SVO had smaller injectors, than the later SVO or the XR.

Here's what I found.   I used the Mitchell OnLine for the comparison data.

All pins and functions are the same, with the following exceptions;

Pin 31 is the Premium Fuel switch pin for the SVO.  It is not shown on the
XR diagram.  Wonder if the function is still present in the EEC though....
:)

Pin 32 is the Boost control on both, but the systems are very much
different on the two cars.  The SVO has an additional electronic box under
the hood, near the boost solenoid to drive it. The XR drives it's solenoid
directly off of the EEC.  I would check the actual outputs on both cars.

Pin 34 is the Data Output Link function on the XR, but is not used.  Not
found on the SVO diagram.

Pin 54 is the "WAC" output on the XR.   This output is shown as only being
used to turn on a fan in the TBird and Cougar.  Not shown as being used on
the XR.  This function is not found on the SVO diagram.

I really hope that Mitchell used the correct diagram for these cars, and
didn't just put the TBird/Cougar schematic here because it was similar. 
Then again, I've seen this alot, so the overlapping useage of diagrams
probably originated at Ford.

I'll post how it runs, afterwards. 

The only problem I can see is that I would now be running an XR EEC with
the big vane meter, which Neil says is bad.  Shoot.

Dave
DCompton@SmartWorx.com
http://www.SmartWorx.com/DCompton