Question about 1996 Pontiac Sunfire

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Map sensor Would a faulty map sensor have an effect on the transmission? It's an automatic but it sometimes dosen't shift out of low gear yet other times it runs fine....any suggestions? Thanks

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Manifold absolute pressure would not affect the transmission. It measures air flow and send the to he ECM (engine control module). Check the fluid level in the transmission. You may also have a plugged filter in the transmission and this will tend the keep the transmission in low gear because the sensor is not getting enough pressure to switch gears. In which case do a filter, gasket and fluid change.

Posted on Apr 23, 2013


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Posted on Jan 02, 2017

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SOURCE: automatic transmission will only shift manually

its the filter. changing the filter will fix this malfunction.

Posted on Mar 09, 2009

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SOURCE: 1991 firebird will not idle cold and bogs down while driving

This sounds like a fuel issue to me. If I am not mistaken, this engine has two injectors running on a separate fuses. Remove the air cleaner assembly, and make sure both are firing while engine is running. If so, then check the fuel pressure. If you have a fuel pressure gauge, connect it to the fuel rail, and start it up. Remove the vacuum line from the fuel pressure regulator to see where it is set. You should have at least 36lbs of fuel pressure. If the pressure is too low, check the fuel filter. It may be clogged, or you might have a weak fuel pump.

Also you changed the throttle position sensor, you will need to make sure it is set properly.

hope this helps,

Posted on Mar 24, 2009

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SOURCE: 97 firbird automatic not shifting properly when accelerating some

You could change the fluid and add a good conditioner like lucas, but even if it works better, you are only buying time. Unit is likely beginning to wear out.

Posted on Apr 15, 2009

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SOURCE: gear shift won't move out of park sometimes

look for transmission shift interlock solenoid fuse.or a bad brake switch will cause transmission not to come out of park.

Posted on May 16, 2009

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SOURCE: Idles rough and is hard to start apears to run better after it warms up. Have replaced the ICO, TPS, and the map sensors with no effect.

You can clean the EGR. No promise it will work. I have an idle problem on my `97 Grand Am Se. Shop told me I could clean it and it might solve my problem. 
Just remove the EGR with the 2 bolts from the top of the manifold behind the throttle body if you have a 3.4 v6 like I do. Then leave it upside down with throttle body cleaner in it. Fill the EGR level with cleaner and let it soak for at least 30 min or more. Then reinstall. 
This will remove any carbon on the inside which plugs the needle from pushing out at highway speeds. Hope this helps. If the problem returns in a week or so then replace with new EGR. New EGR is about $100-200! Cleaning seems to have helped my car did that about 3 weeks ago.
If you have a service engine light on turn the key to the run position on the ignition, pull the fuse to the ECM (batt) and disconnect the wire harness to the EGR. Reinstall it after a 1 min, That will clear all the codes in the ECM and reset everything.
Once you place the ECM fuse back in, start the car. It may stall but let it, DO NOT TOUCH ANY THING. The ECM need to relearn the EGR and engine from all it's sensors like the first time it was started. Just start it up again and it should be like the day it came off the assembly line and will relearn everything.
Good luck and just drive it like you always. If you decide to change the EGR valve, you still need to clear the ECM as mentioned above for the ECM to relearn the new EGR valve. Hope this helps and keep me posted.

Posted on May 25, 2009

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Ok 1989 f super duty no start when hot. showing codes 112,117 122 and998

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Oct 05, 2015 | Cars & Trucks

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On the SLK 280 sometimes cannot go above 30 MPH doesn't happen all the time just started happening.

it dosnt want to shift? or is the motor losing power if it dosnt want to shift it could be the speed sensor

Mar 20, 2013 | 2007 Mercedes-Benz SLK 280

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My 2004 Trailblazer is not starting every time. Sometimes it takes up to 5 tries to start. The codes I'm getting are P0106, P0420, P0410, &P0128. I'm on a budget so fixing them all at o

i have a 1997 blazer with the 4.3 and right now i have the ecm temp sensor unplugged. this does effect the way it starts in the cold. this particular sensor is on the front of the intake in front of the thermostat housing. this also effects the shift timing as well.

Oct 11, 2012 | 2004 Chevrolet TrailBlazer

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My 2004 GMC Envoy has two trouble code readings of 106 & 128. But the light will come on for a while then it will stay off for a while. The auto parts compny that should me the readings said it could...

Hello there,. Below is the detailed information which you asked for.

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P0106 - MAP/Barometric Pressure Circuit Range/Performance ProblemOBD-II Trouble Code Technical Description

Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem

What does that mean? The Powertrain Control Module (PCM) uses the Manifold Absolute Pressure Sensor (MAP) to monitor engine load. (NOTE: Some vehicles have a Barometric Pressure (BARO) sensor that is integral to the Mass Air Flow (MAF) sensor and do not have a MAP sensor. Other vehicles have a MAF/BARO and a redundant MAP sensor where the MAP sensor functions as a backup input in case of MAF failure.) The PCM supplies a 5 Volt reference signal to the MAP sensor. Usually the PCM also supplies a ground circuit to the MAP sensor as well. As the manifold pressure changes with load, the MAP sensor input informs the PCM. At idle the voltage should be 1 to 1.5 Volts and approximately 4.5 Volts at Wide Open Throttle (WOT). The PCM looks for any change in manifold pressure to be preceded by a change in engine load in the form of changes in throttle angle, engine speed, or Exhaust Gas Recirculation (EGR) flow. If the PCM doesn't see any of these factors change while detecting a rapid change in MAP value, it will set a P0106.
Causes A P0106 could be caused by:

  • Bad MAP sensor
  • Water/dirt intrusion affecting MAP sensor connector
  • Intermittent open in the reference, ground, or signal wire for the MAP sensor
  • Intermittent short in the reference, ground, or signal wire for the MAP sensor
  • Ground problem due to corrosion causing intermittent signal problem
  • A break in the flexible air intake duct between the MAF and the intake manifold
  • Bad PCM (do not assume the PCM is bad until you've exhausted all other possibilities)
Possible Solutions Using a scan tool, watch the MAP sensor value with the key on, engine off. Compare the BARO reading with the MAP reading. They should be roughly equal. The voltage for the MAP sensor should read approx. 4.5 volts. Now start the engine and look for a significant drop in the MAP sensor voltage indicating the MAP sensor is working.
If the MAP reading doesn't change perform the following:
  1. With the Key on, engine off, disconnect the vacuum hose from the MAP sensor. Using a vacuum pump, pull 20 in. of vacuum on the MAP sensor. Does the voltage drop? It should. If it doesn't inspect the MAP sensor vacuum port and vacuum hose to manifold for a restriction of some kind. Repair or replace as necessary.
  2. If there are no restrictions, and the value doesn't change with vacuum, then perform the following: with the Key on and engine off and the MAP sensor unplugged, check for 5 Volts at the reference wire to the MAP sensor connector with a Digital Voltmeter. If there is none, check for reference voltage at the PCM connector. If the reference voltage is present at the PCM connector but not the MAP connector, check for open or short in the reference wire between MAP and PCM and retest.
  3. If reference voltage is present, then check for existing ground at the MAP sensor connector. If it isn't present then repair open/short in the ground circuit.
  4. If ground is present, then replace MAP sensor.
Other MAP sensor trouble codes include P0105, P0107, P0108 and P0109.
P0128 OBD-II Trouble Code Technical Description

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
What does that mean? This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125
In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolantmag-glass_10x10.gif temperature (ECT) sensor reading, and the speed of the vehicle.

Causes A code P0128 may mean that one or more of the following has happened:

  • Low engine coolant level
  • Leaking or stuck open thermostat
  • Faulty cooling fan (running too much)
  • Faulty coolant temperature (ECT) sensor
  • Faulty intake air temperature (IAT) sensor
Possible Solutions Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code:
  • Verify coolant strength & level
  • Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary.
  • Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary.
  • Verify proper intake air temperature (IAT) sensor operation, replace if necessary.
  • If the above items check out good, replace the thermostat

Sep 24, 2011 | 2004 GMC Envoy

2 Answers

Won't accelerate on highway. Is it a transmission

Won't accelerate on highway? At what speed (estimate) are you traveling before you "punch it". Is the engine a 3.4 or a 3.8? Is the check engine light on? Is it flashing?

These are a few questions I need to know to try to isolate the problem, but to put you in a ballpark of possible causes, causes could be (but not limited to):
poor grade of fuel
faulty secondary ignition components (spark plug wires, plugs)
clogged fuel filter
insufficient fuel pressure
a partially blocked catalytic converter (will aslo cause the floor to be a little warm)
a faulty map sensor
a faulty egr valve
a faulty transmission shift soleniod
a faulty vehicle speed sensor
low transmission fluid level
partially or blocked transmission fluid filter
transmission fluid has weaken due to age (needs flush)

Sep 02, 2011 | 2001 Chevrolet Monte Carlo

1 Answer

4 cyl. 2006 G6. P0106 code is present, engine light is on, car hard shifts from 1st to 2nd gear (automatic). Mechanic states NOT the transmission, but, Map or Baro pressure circuit is out of range. Sensor...

you will need to some testing to islate problem

Turn ON the ignition, with the engine OFF.
Disconnect the MAP sensor.
Connect a voltmeter between the MAP sensor 5-volt reference circuit and a good ground.
Measure for a proper range of 4.8-5.2 volts between the MAP sensor 5-volt reference circuit and a good ground.
If the voltage is less than the specified range, then test the circuit for a high resistance. If the is normal, replace the ECM. If the voltage is more than the specified range, then test the circuit for a short to voltage. If the circuit is normal, replace the ECM.With the MAP sensor still disconnected, use the scan tool to observe the MAP Sensor parameter for the proper value of less than 12 kPa.
If the MAP Sensor parameter is more than 12 kPa, then test the MAP sensor signal circuit for a short to voltage. If the circuit is normal, replace the ECM.Connect a jumper wire between the MAP sensor 5-volt reference circuit and the MAP sensor signal circuit.
Use the scan tool to observe the MAP Sensor parameter for the proper value of more than 103 kPa.
If the MAP Sensor parameter is less than 103 kPa, then test the MAP sensor signal circuit for a high resistance. If the circuit is normal, replace the ECM.Turn OFF the ignition, and all electrical accessories. Allow sufficient time for the control module to power down before taking a resistance measurement.
Measure for a proper value of less than 5 ohms of resistance between the low reference circuit of the MAP sensor and a good ground.
If the resistance is more than 5 ohms, then test the circuit for a high resistance. If the circuit tests normal, replace the ECM.If the MAP sensor circuits test normal, then replace the MAP sensor.

Jun 07, 2011 | 2006 Pontiac G6

1 Answer

I have a 1999 malibu it start and run for short time but them stop.if i started again them it dosent have any signal at the spark plug. it have been 2 days that this is goin up this mornig i started and...

map sensor control fuel delivery and ignition timing.the map sensor is your load sensor when engine closed throttle high vacuum wide open throttle low vacuum.need more fuel and spark.when your engine at wide open throttle. low vacuum.cause electrical volts to increase to 5 volts in which pcm will increase fuel pressure and spark.the map sensor does control spark also.replace map sensor erase code and see what happens.

Apr 16, 2011 | 1998 Chevrolet Malibu

1 Answer


It could just be a bad signal from the MAP sensor or a poor connection at the sensor. Or a bad MAP sensor itself. Maybe the vacuum line is off or broken.

Manifold Absolute Pressure (MAP) sensor measures the changes in the intake manifold pressure which result from engine load and speed changes, and converts this measurement into a voltage output.

A closed throttle on when the engine is decelerating would produce a relatively low MAP output, while a wide open throttle would produce a high output. Manifold absolute pressure is the opposite of what you would measure on a vacuum gage. When manifold pressure is high, vacuum is low. The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the PCM to automatically adjust for different altitudes.

The PCM sends a 5 volt reference signal to the MAP sensor. As the manifold pressure changes, the electrical resistance of the sensor also changes. By monitoring the sensor output voltage, the PCM can determine the manifold pressure. A higher pressure, low vacuum (high voltage) requires more fuel, while a lower pressure, higher vacuum (low voltage) requires less fuel.

A high or low voltage fault in the MAP sensor circuit should set a DTC P0107 or DTC P0108. If the MAP sensor sends an intermittent zero voltage signal to the PCM, a DTC P0106 will set.

Oct 13, 2010 | 1998 Chevrolet Malibu

1 Answer

Transmission problems

automatic shifting gearboxes have speed sensors and servos that can sometimes be replaced at home if you can turn a wrench, or it could be just a bad maf/map sensor or pedal position sensor.

Apr 30, 2009 | 1998 GMC Sierra

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