Is this an issue with MAF or something else

[fredperry]

Hi Guys,

I am struggling with my Explo'99 from almost 4 months now. Yesterday I plugged my car to computer and did detailed check it is showing that MAF is not working correctly. I have three MAFs replaced one by one and did a check on computer it always showed that MAF is not working correctly. I am wondering if it is possible that I have bought 3 demaged MAFs or it can be something else - like some input to MAF...but I really dont know. Thanks for your help.

 

[96eb96]

What criteria are you using to determine the MAF is bad?

 

[fredperry]

actually I was told this by my mechanic. He told me that on the scale MAFs gave signal below 30 units...not sure what kind and it should much more. I am wondering if there is any other simple way to check if MAF is ok or not. Also: Does for example problem with intake gaskets have any fluence on MAF work?

 

[2000StreetRod]

MAF Sensor Test Procedure

MAF Sensor Test Procedure for my SOHC V6

 

[fredperry]

StreetRod great link and post thank you ! Just one more question is there a possibility that MAF is OK but works incorrectly because of some other parts issues?

 

[2000StreetRod]

poor electrical connection

On my 2000 SOHC V6 the MAF sensor and the IAT sensor are integrated into the same housing. The gray and the gray/red wires (1st & last pin on MAF sensor connector) are associated with the IAT sensor. The other 4 wires are associated with the MAF sensor. The black wire is connected to chassis ground. The light blue/red wire connects to PCM pin 88 (sensor input). The tan/light blue wire connects to PCM pin 36 (sensor return). The red wire connects to +12 volts from the PCM power relay.

There could be a poor electrical connection to one of the MAF sensor pins. Sometimes the pins on the PCM connector get pushed back into the connector housing. The PCM checks for a reasonable signal from the PCM and reports an out of range condition. Possible diagnostic trouble codes are:

P0100 MAF circuit malfunction
P0101 MAF circuit range/performance
P0102 MAF circuit low input
P0103 MAF circuit high input
P0104 MAF circuit intermittent

Are any of the above codes set?

 

[fredperry]

Thanks for the reply! None from the above so probably MAF is bad. From couple of months I have problems with cold start. My mechanic replaced oxygen sensors, MAF (twice), spare plugs, stepper, one of the temperature sensors...but still nothing my errors are here:

P0155 Heated O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean
P1151 Lack Of HO2S21 Switch - Sensor Indicates Lean
P1152 Lack Of HO2S21 Switch - Sensor Indicates Rich
P0300 Random/Multiple Cylindre Misfire Detected
P0171 System Too Lean (Bank 1)

thank you

 

[JDraper]

If it's only a cold start issue, have you looked at the idle air control valve (IAC)? It's basically the equivalent of a choke on a carbureted engine. It's function is to control the amount of air the motor sees at idle. If it's malfunctioning (and it won't throw a code if it's bad), it will affect your idle, especially in cold temperatures.

 

[2000StreetRod]

stepper vs IAC valve

I suspect that the "stepper" referred to as being replaced is the equivalent of the IAC valve.

 

[2000StreetRod]

O2 sensor connections?

Thanks for the reply! None from the above so probably MAF is bad. From couple of months I have problems with cold start. My mechanic replaced oxygen sensors, MAF (twice), spare plugs, stepper, one of the temperature sensors...but still nothing my errors are here:

P0155 Heated O2 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)
P1131 Lack Of HO2S11 Switch - Sensor Indicates Lean
P1151 Lack Of HO2S21 Switch - Sensor Indicates Lean
P1152 Lack Of HO2S21 Switch - Sensor Indicates Rich
P0300 Random/Multiple Cylindre Misfire Detected
P0171 System Too Lean (Bank 1)

thank you

The first thing to do is to eliminate the P0155 DTC. If the heater to your O2 sensor doesn't work then it will take a long time before the O2 sensor gets hot enough to work properly. Check the electrical connections to the downpipe sensor on the left side of the vehicle.

 

[fredperry]

yes, exactly I've reffered to IAC valve, that was actually the first thing I have replaced. Thanks for the idea. I am rookie in this kind of things :/ and mechanics are not so experienced in this kind of cars here. Could you plss give some more details where to find this connection to downpipe sensor. do you have by chance a photo of it? Thanks so much for your help

 

[2000StreetRod]

precat sensor

The bank 2, sensor 1 is the one on the downpipe downstream from the exhaust manifold and prior to the catalytic converter. For some reason I can't post any jpg images at this time. It may be due to forum problems. The connector for the sensor is above the transmission shift linkage. It is difficult to access. I suspect that you have a bad connection to the sensor. Or the wiring could be laying against the exhaust pipe and shorted out.

 

[2000StreetRod]

Not the MAF sensor

I saw your other post looking for another MAF sensor. I think you are wasting your time and money. Your faults do not indicate a bad MAF sensor. The faults indicate a miswired or poor electrical connection to the forward O2 sensor. Just because your mechanic replaced your O2 sensors doesn't mean it was done correctly. Some mechanics have carelessly connected the right side O2 wiring to the left sensor and vice versa which totally confuses the PCM.

 

[G-96XLT]

he is in poland after all. I think the problem is with the mechanic and not the ex.