This tutorial will show how to test the manifold absolute pressure (MAP) sensor (and DTC P0106, P0107, P0108, P01107) on your Isuzu Amigo, Rodeo, Trooper or Honda Passport (1988-1997) with step-by-step testing instructions.
You'll be able to definitely say, "The MAP sensor is BAD" or "The MAP sensor is OK, and not the cause of the MAP code or issue". All you'll need is a multimeter, since a scan tool isn't required for the test.
To help you navigate this article a little easier, here are its contents at a glance:
- Important Tips And Suggestions.
- Symptoms Of A BAD MAP Sensor.
- How Does The MAP Sensor Work?
- TEST 1: Checking The MAP Signal
- TEST 2: Checking The MAP Sensor's Power Circuit.
- TEST 3: Checking The MAP Sensor's Ground Circuit.
- MAP Sensor Code Won't Go Away.
Important Tips And Suggestions
TIP 1: When testing for the signals (in the MAP sensor wires), you've got to be careful not to short the wire to power (12 Volts) or you could fry the Fuel Injection Computer.
TIP 2: You'll notice that the tests are done with a vacuum pump. If you don't have one, and you live in the States, you can run down to AutoZone or O'Reilly Auto Parts and rent one (it's free -deposit required tho' to make sure you take it back). If this option is not available to you, you can also use the good ole' lungs, but it won't be the most accurate (it works, but I don't recommend it).
TIP 3: A scan tool is a must have tool for any Trouble Code Troubleshooting, but the way I've designed this test, you don't need one. What you do need is a multimeter, which can either be an Analog one or a Digital one.
Symptoms Of A BAD MAP Sensor
You'll have the CHECK ENGINE LIGHT on, for sure, on your instrument cluster and one of several of the following symptoms:
TPS Diagnostic Trouble Codes P0106, P0107, P0108, P01107 stored in the vehicle's computer's memory and lighting up the check engine light.
Really BAD gas mileage. You know that it's not the price of Gasoline that has you thinking that your Isuzu pick up or SUV is costing you more at the pump.
No power and/or hesitation as you accelerate the vehicle. Idle is not even.
How Does The MAP Sensor Work?
The manifold absolute pressure sensor's job is to measure the intake manifold's vacuum and then transmit this info the Fuel Injection Computer (also known as the PCM= Powertrain Control Module). In a nutshell, this is how the MAP sensor Works:
When you turn the Key to the On position and then start the engine, the MAP sensor gets power thru' the wire labeled with the number 1. This power is in the form of 5 Volts.
ground is provided to the MAP sensor by the fuel injection computer thru' the circuit labeled with the number 3.
With the engine running, the pistons downward travel creates a vacuum in the intake manifold. Now, since the MAP sensor is connected to the intake manifold, this vacuum also acts on the innards of the MAP sensor.
So then, no matter what the amount of vacuum inside the Intake due to different Engine RPM's, the MAP sensor is able to always measure these changes and send this info to the fuel injection computer thru' the wire labeled with the number 2.
The Fuel Injection Computer uses this info (that the MAP sensor provides) to control Fuel Injection, Ignition Advance and host of other things to keep your engine running smoothly on your Isuzu vehicle.