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I have a 88 fiero with a 2.8 tbi and the voltage coming in on the grey wire is 5.1 and the blue wire is 4.8 at closed throttle. I have replaced both the ecm and the tps is it possible one was bad .

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6ya6ya
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Posted on Jan 02, 2017

  • 17 Answers

SOURCE: 2001 Ford Explorer Sport Throttle Position Sensor

Hi, Take a little time to check all earth mounts,There are some fine earthwires under the looms running from air intake if one of these is broken or dirty it can cause all the symptoms you describe. All the best. Phil

Posted on Sep 11, 2008

SOURCE: 91 jimmy 4.3 will not idle cold or hot

The distributor module and pick up coil

Posted on Mar 14, 2009

michigan man
  • 3533 Answers

SOURCE: Replacing the throttle position sensor on my 93 Ford F150

try autozone.com to see if they have your car listed for diagrams pictures and step by step instructions if your car is not listed then try your local library they have all the car manuals and even copy them for you

Posted on Mar 21, 2009

  • 255 Answers

SOURCE: no spark but turns over replaced ignition module,coil,ecm

could be in the crank position sensor

just a thought shack

Posted on Apr 18, 2009

  • 89 Answers

SOURCE: i have an 88 chevy truck, not getting fuel out of inector

I had a similar problem on an 84 Lincoln Mark VII. Found out it was a ground wire that had broken running from the wiring harness to the fender well. The wire was broken inside the shielding and not visible. You might consider going through and checking all of the plug connections for corrosion as well. This may not solve the problem but certainly easy to check.

Posted on Dec 27, 2009

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1 Answer

Have a 1990 isuzu trooper 6 cylinder throttle body need wire color codes to replace injector connectors


t
that is a very old car.this.

no you do mean it has 2 injectors, be nice to say "I have the 2 injector engine" a TBI injected engine .
its the 2.8L v6?

here it is, log in to mitchell's diy and read>?
first is 4 banger.

26297084-u1skeagojbjhu3ucj4o4k3kf-1-0.jpg the 6cylinder with 2 injectors TBI its called.
throttle body injected. so the blue/black wires are 12v power.
and the 2 injectors fire, blue and green. ISC valve on right.

26297084-u1skeagojbjhu3ucj4o4k3kf-1-1.jpg

Oct 01, 2016 | Isuzu Cars & Trucks

1 Answer

I have a 88 fiero 2.5L it idles beautifully but i put in in drive and it backfires then shuts off


fuel pressure? tbi needs like 14 lbs.
ECM failure is also a thought,they had a habit I recall
The backfire part is odd, would think crank sensor or lock up solonid
but it wouldn't backfire. Tough one ,hoping someone else will
chime in.

Apr 15, 2013 | Pontiac Fiero Cars & Trucks

1 Answer

Checking tbi injecter voltage


On a 1988 model which should be the same as 87, I show two injectors in the throttle body. Inj 1 has red and blue wires and inj 2 has green and white wires.
The red and white wires should be battery voltage, and the other two are ground signal wires from the computer.

Dec 20, 2012 | Chevrolet Silverado 2500 Cars & Trucks

1 Answer

87-88 fiero runs but only tops out at about 30 after i get up to speed which takes a good block or two slowly. smokes a little but i think its because it has sat for 6 plus years. any tests i can run or...


I had the same problem, maybe 25MPH top speed and difficult to start. Changed out the old gas, installed fresh high octane-problem was worse.
The ignition system was faulty. Pull a High voltage wire and you should see a bright blue spark and hear a crackling noise. If you see a weak yellow spark, you found your problem.
Could be a bad/weak ignition module-rather famous in a Fiero due to heat exposure. Bad pickup coil in the distributor. I replaced the entire (rusty) distributor with a new/rebuilt unit a long with a new Ignition module. Solved the problem!

May 04, 2012 | 1988 Pontiac Fiero

1 Answer

When i punch on the gass my 97 tahoe hesitates


usually a bad MAP sensor or TPS. I would test both. Let me know if you have questions and provide test results for repair advice.

MAP Sensor TESTING
See Figures 3, 4 and 5
  1. Backprobe with a high impedance voltmeter at MAP sensor terminals A and C.
  2. With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
  3. If the voltage is not as specified, either the wiring to the MAP sensor or the ECM may be faulty. Correct any wiring or ECM faults before continuing test.
  4. Backprobe with the high impotence voltmeter at MAP sensor terminals B and A.
  5. Verify that the sensor voltage is approximately 0.5 volts with the engine not running (at sea level).
  6. Record MAP sensor voltage with the key ON and engine off.
  7. Start the vehicle.
  8. Verify that the sensor voltage is greater than 1.5 volts (above the recorded reading) at idle.
  9. Verify that the sensor voltage increases to approximately 4.5. volts (above the recorded reading) at Wide Open Throttle (WOT).
  10. If the sensor voltage is as specified, the sensor is functioning properly.
  11. If the sensor voltage is not as specified, check the sensor and the sensor vacuum source for a leak or a restriction. If no leaks or restrictions are found, the sensor may be defective and should be replaced.



jturcotte_512.jpg

Fig. Fig. 3: Location of the MAP sensor-TBI system shown


jturcotte_513.jpg

Fig. Fig. 4: Probe the terminals of the MAP sensor to check for proper reference voltage


jturcotte_1792.gif

Fig. Fig. 5: Manifold Absolute Pressure (MAP) sensor wiring diagram








TPS TESTINGSee Figures 2, 3 and 4

  1. Backprobe with a high impedance voltmeter at TPS terminals A and B.
  2. With the key ON and engine off, the voltmeter reading should be approximately 5.0 volts.
  3. If the voltage is not as specified, either the wiring to the TPS or the ECM may be faulty. Correct any wiring or ECM faults before continuing test.
  4. Backprobe with a high impedance voltmeter at terminals C and B.
  5. With the key ON and engine off and the throttle closed, the TPS voltage should be approximately 0.5-1.2 volts.
  6. Verify that the TPS voltage increases or decreases smoothly as the throttle is opened or closed. Make sure to open and close the throttle very slowly in order to detect any abnormalities in the TPS voltage reading.
  7. If the sensor voltage is not as specified, replace the sensor.



jturcotte_514.jpg

Fig. Fig. 2: Using a DVOM, backprobe terminals A and B of the TPS sensor to check for proper reference voltage


jturcotte_515.jpg

Fig. Fig. 3: Using the DVOM, backprobe terminals C and B of the TPS sensor, open and close the throttle and make sure the voltage changes smoothly


jturcotte_1793.gif

Fig. Fig. 4: Throttle Position Sensor (TPS) wiring diagram

May 30, 2011 | Chevrolet Tahoe Cars & Trucks

1 Answer

What are the electrical readings on the throttle positioning sensor


The throttle position sensor has both an idle contact switch and a basic 3 wire potentiometer that measures throttle angle opening. The idle switch and the throttle potentiometer share a ground wire.
To test the sensor first you have to verify that the wiring is intact by
1. Disconect the sensor and with a volt meter check the 4 wires. I have attached a wire diagram and picture of the pin layout to make it easy for you.
Pin 1 ( Yellow wire) is the PCM reference voltage. Specification is 5V
Pin 2 ( Red and Green wire) is the signal wire for the TPS. Specification is 5V
Pin 3 (Blue and white wire) is the idle switch. Specification 5V. Please note that this circuit is not actually used by this year Sedona so some vehicles are missing the wire.
Pin 4 (Black and yellow wire) is the ground. Specification: continuity to ground ( less than 1 ohm)
If the voltages are correct next you want to check the sensor.
1. Connect the throttle sensor connector.
2. Key on engine off
3.With a voltmeter measure terminal 2 of the sensor with the throttle closed, Specification is .2 to.4 volts.
4. With ta voltmeter monitor terminal 2 with the throttle fully open.The specification on terminal 2 is 4 to 4.4 V.
5. Slowly open and close the throttle while monitoring terminal 2 and make sure you have a smoot increase and decrease in voltage as the throttle is moved from close to open throttle and returned to idle.


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Jan 12, 2011 | 2005 Kia Sedona

1 Answer

1990 Chevy Lumina showing codes 12 and 21. What are they?


code 12 flashes any time trouble codes are pulled without the car running. It is normal and think it has something to do with not receiving distributor pulse.

Code 21 has to do with the TPS (throttle position sensor) voltage being to high. You'll need a DVOM (digital volt ohm meter) to check this out. Unplug the TPS sensor and check for 5volts on the grey wire, and make sure the black wire has a good ground. If those check out plug the sensor back in. Back probe the blue wire. you should see around .5 volts with the throttle closed. The voltage should go up smoothly as you slowly open the throttle. At wide open throttle the voltage should be around 4.9 volts. If any of the above three are not true I would suspect a bad throttle position sensor.

Oct 24, 2010 | 1990 Chevrolet Lumina

1 Answer

Do you know plug wire line up for a 1995 pontiac fiero 2.3


The Pontiac Fiero was made from 1984 to 1988
In the 84 thru 88 Fiero's they had the 2.5L In-Line 4-Cylinder or the 2.8L V6.
I have included both below

For the 2.5L In-Line 4-Cylinder:
Firing Order:
1 - 3 - 4 - 2
Cylinders:
.........(back)............
|...1....2....3....4...|
.........(front)
Distributor Connections:
..............2
...................(+)
....4
....................1
(+)
..........3

For the 2.8L V6:
Firing Order:
1 - 2 - 3 - 4 - 5 - 6
Cylinders
.......(back).........
|...1.....3.....5...|
|......................|
|...2.....4.....6...|
........(front)
Distributor:
............2
......1.........3
(+)...............(+)
......6.........4
............5

Let me know if this helped, or if you have additional information or questions. Feel Free to contact me at FixYa.com!

Jul 09, 2010 | 1985 Pontiac Fiero

1 Answer

Fiero Engine is spitting


Try replacing the Idle Air Control Valve. If that does not work (which it should) try fixing the Throttle Postion Sensor.

Apr 25, 2009 | 1986 Pontiac Fiero

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