20 Most Recent 2003 GMC Envoy Xl - Page 9 Questions & Answers

P0106 - MAP/Barometric Pressure Circuit Range/Performance Problem

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.

Potential Symptoms: The following could be symptomatic of a P0106:
* Engine runs rough
* Black smoke at tailpipe
* Engine will not idle
* Poor fuel economy
* Engine misses at speed

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, P0106, P0107, P0108 and P0109.

I hope this helps to solve it (remember to rate this answer).

Replace the belt. No need to use belt dressing, the noise will just come back, if indeed it is the belt and not a pulley going bad.

is there still power steering fluid in the reservoir?

Most certainly, should be part of regular maintence since Envoys don't have a pcv valve, so the throttle body tends to gum up quickly. Should keep it nice and shiny, using throttle body cleaner. Very simple job. One thing to remember, disconnect the battery while cleaning it. There is a tiny stepper motor that will fry if there is power on and you're moving the butterfly. Also, be careful, the butterfly is very very sharp.

This sounds like a mifire and you may have a bad coil, have the computer scanned for codes, the codes will tell you what cylinder is misfiring, from there replace the sparkplugs and the bad coil.

There was a re-call for Trailblazers for this problem. Check with your dealer on any recalls regarding this.

You'll find that this is actually your thermostat, not the actual sensor itself. Your thermostat is sticking open causing it to run too cool. Replace the thermostat, and that light will go out. I went a year with this problem, replaced the sensor twice, light would still go on. The bad thermostat was causing bad readings by the sensor. Very common problem for Envoys and Trailblazers.

Happens in gear, drive or reverse with your foot on the brake? Normally happen in the morning? Check your motor mounts, and or transmission mounts. I'm going through this right now.

Have a good muffler shop perform a back pressure test.

Try unhooking it overnight to see if it's a short in the car or the battery. If unhooking it stops the drain, look for a short in the car.

Please see my tip at http://www.fixya.com/cars/r5925550-dead_battery_troubleshooting . These are generic instructions. If you get stuck or need specific instructions for your car, please get back to me with model, year and engine info.

fan clutch was replaced?? what kind of noise are you hearing??

Ask the wife if it is really oil or something more like steering fluid/transmission fluid/transfer case or worse front axle assembly. Bottom line, someone has gonna to crawl under there first to get a 20 on the leak. those engines are so packed under the hood, very little can actually be seen from above.

The engine oil pressure need to be tested with a manual gauge hooked up to the engine to get an actual oil pressure reading.

Check the oil level in the engine. Have the oil pressure checked with a manual gauge hooked directly up to the engine to see if the pressure is good.

First thing to do is to clean the throttle body and throttle plate thoroughly. While performing the cleaning, disconnect the battery for about 30 minutes. This will force the PCM to relearn with a clean throttle body. See if this helps with running and the codes. Also make sure the gas cap is tightened properly.

You have to pull the codes and repair that indication. Something is wrong, and continues to be wrong, or the light would go out.

You can take your vehicle to a place like Auto Zone, they can read the fault code with scanner, or you can buy a OBD II scanner for anywhere between $50 to $100. Interpreting the codes may require some knowledge of the car though.

you have to have a computer to reset the chang oil light