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Starting point voltage questions

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Old Jun 22, 2010 | 03:28 AM
  #1  
CamanoWagon's Avatar
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From: Camano Island, WA
Car: For this site, 91 Caprice wagon
Engine: 350 from an 88 truck
Transmission: 700r4
Starting point voltage questions

Got the car running and driving, and beggining to tune.....

Setting the basics, We ran through the IAC/TPS how to's and have run into a snag. The readings are off from what the manual is claiming we should have, as follows:

factory says 5V feed, closed TPS should be .2 to 1.0, WOT should be 4.0-4.5.
Mine reads 6.65V, closed is .8, WOT 5.73.

How am I getting more than 5V in? Is that not supplied by the ECM?
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Old Jun 22, 2010 | 12:59 PM
  #2  
RBob's Avatar
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
Re: Starting point voltage questions

The +5V reference is generated by the ECM. So either the DVM is bad, the voltage is being measured incorrectly, the ECM is bad, or there is a bad ground(s) in the EFI system

RBob.
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Old Jun 27, 2010 | 02:46 AM
  #3  
CamanoWagon's Avatar
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Joined: Oct 2005
Posts: 48
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From: Camano Island, WA
Car: For this site, 91 Caprice wagon
Engine: 350 from an 88 truck
Transmission: 700r4
Re: Starting point voltage questions

TunerPro is reading these within the factory limits. Car is running OK, but not good enough.

Now to the VSS. I am trying to figure out how to get the signal from the Caprice wiring (with a VSS buffer) to the 730 ECM, which wants the input directly from the VSS. So, at this point, comparing the schematics of both cars, I am of the opinion that I need to provide the PPL and YEL wires to thier respective pin locations on the ECM. My fear is what that may do to the cruise control in the Caprice, as it appears the VSS is controlled by these wires, and then to the buffer-then to the ECM. Am I way off?
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