The reference signal to the MAP is 5.80v and rising at ~0.01v per second and the TPS reference signal is 6.11v. Both should be 5v. Any ideas on what could be the cause of this?

 

Faulty sensors would be my guess.

 

The reference signal is sent by the ECM and will be be there even with the sensor disconnected. I'm thinking a bad ECM, but it may be something else like a voltage regulator somewhere.

 

a wire to wire short some where or an ECM problem,

ECM is what limits reference voltage,
unless a 12 volt source is making slight contact with a reference wire but I wouldn't say that was very likely,

check to see that the car is not overcharging
ie. charging over 15volts

 

I tested the reference signal with the ignition on/engine off and the battery is a little weak so if anything the reference signal should be a little low from that. Since there are two sensors recieving the bad reference signal and voltage is not regulated anywhere else after the ECM I think the ECM is the problem... dammit. This would probably be the cause of my rough idle right?

 

yeah if your ref. voltage is to high, your signal is going to be high as well,

this will confuse the ecm,

before doing anything, check all your grounds, and check the resistance in the ground circuits, resistance on ground circuits should be less than 10ohms

use battery neg. post as your ground for your meter and check ref. voltage

if you still have high ref. voltage then start looking at ecm

hard to say without looking myself but I'm leaning towards ecm,

do you need any wiring schematics?

 

I have a GM service manual for an 86 firebird and a general purpose Haynes manual for all 3rd gens so I probably have a wiring diagram or 2 in there somewhere that would apply.

I checked the reference voltage using the battery as the ground and for the TPS it was still 6v. I didn't check the MAP again. I also haven't checked ground wire resistance yet. How should I go about doing this?

 

just noticed you had MAP I only got stuff on MAF,

to check ground resistance, set your DVM to Ohms,

put 1 lead on the ground pin(s) on the ecm plug and the next on a good chasis ground, should be less than 10 ohms

also check engine to battery cable at battery and battery cable to chasis

battery has to be disconnected durning these test,

 

Resistance from the TPS ground to the battery terminal is 2.5 ohms. I believe the TPS, MAT, CTS, and probably the MAP share the same ground line. Is this a legitimate way to test the ground resistance through the ECM or do I actually need to test from the ECM pin. According to my wiring diagram these ground wires go directly to the ECM anyway.

 

you have to isolate the wiring from the ecm and the sensors,
sensors and ecm could give you a false reading, 2.5 is a little high,
your goning to have get diagram off the harness going to the ecm and check resitance with the harness off the ecm,

its the proper way to do it, you could throw an ecm at it if you want but if I were doing it at work I got to go through all the steps right,

I'm a Commercial Transport Mechanic and I specialize in electronics on rigs,
the difference is if I put an ECM on a deisel engine its like $4000 you could probably get a map ecm for like $100


I'm going to see if I can find a step by step break down for high ref. voltage

 

Cool. I have a MAF wiring diagram for an 86. It may or may not be useful.

 

different ecm

 

Looks like my digital volt meter was improperly calibrated. Thus my search continues for the source of my rough idle.