Issue with bogging, no check engine light

[cartracer12]

The MAF sensor is probably only reading a voltage of 2.5 or 3.0v and above. Which accounts for your super poor fuel economy. Bogging at low RPMs etc. The broken skrew might have caused an air leak which will only worsen the problem. I wouldn't test at the PCM its a bit of a hassle to gain access. I would try a MAF sensor from a friend if possible or someone in the community that might live near you as they are fairly expensive to replace.

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[cartracer12]

My MAF reads a minimum voltage of 2.0V where as when it is working properly it should range from .5v at idle to 4.5v at wide open throttle at max rpm.

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[NScrilla]

Okay i did some analysis on this and read the voltages out of the MAF sensor.

What i did was took a 12v multimeter and accesses the 5 wires and read voltage. I did four tests. My theory is the Scanner tool is an easy way to access readings across the different systems of the car. However they all originate at the sensors.

1. With car off.
2. Car off ignition on
3. Car on.

There are five wires connected to the MAF. In order from left to right looking from above.
1. White/Red - this one is the battery wire.
2. Black/White – I think this one is a ground – no volts
3. Green/black – This one gets voltage when engine is running
4. Blue/white – This one gets voltage when ignition on/engine off and ignition on/engine on
5. Orange – This one is a ground or something else – no volts

First test was no ignition/ engine off.

None of the wires measured any voltage.

Second test was ignition on/engine off.

The white/red got around 12 volts, since ignition is on and sensor is getting battery power.
Blue/white got 2.87 Volts. I think this is out of the sensor but maybe not, either way it has power when ignition is on.
All others 0 volts.

Third test is ignition on/ engine on. This one I started when the car was cold and took measurements as it warmed up. I did this since the car seems to work better at different temperatures, with being warm the worst.
White/red got 14.2 volts. Higher now since it has access to running alternator.

Black/white still got 0 volts
Green was very strange. It started at 1.54 volts, as the temp of the engine heated up its volts dropped steadily. Last reading with engine up to mid-range on gauge which is warm was 1.2 volts.
Blue/white was at 2.85 and dropped to 2.73 when temp was warm.
Orange was .02 volts during this test.


Strange thing I also noticed was with key on:
Blue/white 5 volts when not connected to the sensor reading voltage from wire.
Blue/white 2.87 connected
Blue/white 2.5 connected after running to warm temp
Green/Black 0 volts unconnected when reading from wire
Green/Black .73 volts connected to sensor
Green/Black .73 connected to sensor after running to warm.


Does this kinda analysis make any sense to anyone? Anyone think something might be up with these readings?

Thanks!

 

[concept]

Quick question: Did you check everywhere for vacuum leaks? There's a small hose that is close to the firewall at approximate center. I've had this tubing split, twice and if the leak is large enough, the engine tries and can fail to provide enough fuel to arrive at the proper A/F ratio.

Also, did you follow the factory service manual to diagnose the MAF? If so, the correct voltages should be in there.

 

[NScrilla]

K so two things.

1. I don't know anyone with another 1.6L protege and the MAF's are different for the different models so the aunt i have who has a 2.0 wont work. The wrecker has one from a 1.6L that has a broken tranny that he said he would sell me for 40$. I went and put the volt meter to the green/black wire from above and it changes volts with throttle. I fully pulled the throttle cable and the engine revved up but i only saw the volts at 3.5 at its highest. Not any 5 volts. Its not ideling at .5 on any of the 5 wires that are connected to the MAF sensor.

As per car racers post above, could my MAF be out? The manual is sort of laid out very foolishly. It is hard to find stuff. Although is asks me to do tests using a PID reading meter. I just have the code reader.


2. I looked at all the vacuum lines and replaced all i could find as far as i know. I didn't see a small one at the back that you were referring to though. I did take the one off the brake booster that connected to the intake. It was a large vacuum line and it had a big split in it. So i replaced the rest of them also since i had a bunch of extra vacuum line. I noticed something strange in the top left of the engine bay (by the passenger). There is a sensor that has a connector connected to it. It has a vacuum line connected to it that dosnt go anywhere at all. I disconnected the sensor and got code p0108 which is called the "BARO circuit" or so the strange manual says. Im not sure if this vacuum line that it has is supposed to go anywhere but right now it just goes to the engine bay basically. I could have missed a vacuum line although i don't think so cause from the look at the diagram in the manual i think i got them all. Although the diagram isnt very good. Are there any that are underneath the intake or something?

I think fixing the vacuum line from the brake booster has made things better. But it still isn't right. Ill have to drive it more to make sure though.

Thanks!

 

[NScrilla]

Alright well i fixed it. Basically i went to the wrecking yard and got the MAF sensor from a car there. He only charged me 20 and gave me the air filter with it for free since it was in pretty good shape and mine needed replacement. It was a bit of driving there but i popped it in once i got it and like magic the car runs great! I guess the sensor was malfunctioning as determined by the faulty voltages and running richer than it should have which caused performance issues and 30% less mileage. So happy to have it working properly again.

Now the only question is should i clean the MAF with the cleaner that i now have? Or should i just leave it alone haha.

Thanks!