Subaru p0103 code

Hello,

Ok, the first time you changed the MAF did you clear the code or did it turn off on its own?

Most of the time you either need to clear the code, drive it anywhere from 300 - 800 miles or 50 - 100 key starts.

Do this disconnect the MAF and start car... How did it run?

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I cleared the Maf sensor the first time, I didn't clear it this time, but I did disconnect it and when I plugged it back in it got worse with the same symptoms

How did it run with it disconnected?

It still did not run well, although the first time I realized it was the Maf in November when
It was running unplugged it still wasn't that stable as far a rpms

Although I really need to leave for school tomorrow and I was wondering if driving this car would be ill advised. I can work on it out there a lot easier I would be looking for a temporary quick fix tomorrow anyways

Ok, all the simptoms indicate a problem with something in the MAF - whether it be the MAF itself, the Wiring or in the ECM.

First thing to check is the wiring - follow it as far as you can look for bare wire grounding itself out.

I would not trust it being driven no farther than a garage.

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Wiring seemed all set, it has housing. All the ones I got access to seemed new. I check all the grounds I could and cleaned them up. The problem is still there. The rest of the sensors are working fine so I didn't think it could be ECM. Any other ideas the problem seemed worse when idling so originally I thought it could be the iacv but it definitely misfires while running at higher rpms.

So a clearer description of what happened when the Maf is disconnected is it would rev up to 1500-2000 rpms stay there for 2 seconds then die, or it will stay on but the rpms wave between 100-500 rpms and it shakes and is good. When driving it to get the code at around 2000 rpms it was shakey and would lunge forward or lose power. I have installed the 3rd new MAF in the last month so I'm pretty confident its not that. Any ideas would be greatly appreciated. The car is only worth 1000 now and I really don't want to spend more money than it is worth. I really do appreciate your responses and thank you for your time. If there are any other possible ideas I will keep you updated

Ok, do you know if the Coil Pack is Original or not? Since you say it has a miss at high rpms, I am thinking possibly the coil is starting to fail when gets warm. And it could be just one tower and not all off them.

With engine running one at a time pull plug wires off and then put back on noting and changes in engine performance. example: you pull a wire off and engine dies, or you pull wire off and no difference than with wire on.

Also are the wires original? I know you said you change plugs change in Nov.

One more thing pull each plug and take note of condition, check out link below for plug conditions....scroll down toward bottom of page...

https://www.2carpros.com/articles/how-to-change-spark-plugs

Post results...

There was no change really when I took them out. I did notice one was a little loose and it is idling better now. But it will still misfire at even 1500 rpms. All the spark plugs are good and the check engine light is till on. Do you think it could still be the coil?

Are the Wires Original? If not sure take a good look at them, are there any cracks or is the plastic feel hard. If cracked or casing is hard would suggest replacing wires.

Could still be the coil.

Here's what to do next...

With a Philips screw driver remove one of the spark plug wires, place the screw drive in the boot, then place the screw driver near a good ground, make sure there is a gap of about and 1/8" to a 1/4" you may need someone to start engine, you will need to look at the color of the spark - color should be a Bright Bluish/White if Orange Spark is weak and will need to replace Coil. Check all plug wire the same way.

Replaced the coil and it didn't help. Although it seems like the car is doing better at idle now it just is struggling with the acceleration

Ok, as long as it improved. Now you say it struggle with acceleration, so when was the last time the fuel filter was changed? A clogged filter can cause the weak acceleration. You can sort of check the filter by removing it and dumping it out from the tank end if a lot of debri comes out then replace it and see what happens.

Also have you cleared the engine code?

I take it you test drove the car and thats how you found the acceleration problem. And I also take it that the engine miss is gone.

I haven't cleared the engine code and back in November when I was struggling with this I changed thee fuel filter. Any chance I could be that unlucky and have gotten yet another bad Maf sensor?

Go ahead and clear the code and drive it see if code come back.

How did it drive other than the acceleration problem?

It is possible but getting 3 bad one's!?!? Not sure could happen I guess. One thing I didn't ask about just for some reason just thought of. Is are there any cracks or vacuum leaks in the air tube?

If drives good other than acceleration problem it should be no problem to drive it to school tomorrow. And we can continue diagnosing the problem.

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I just reved it in neutral to find out the acceleration was off

Take it for a short drive...

I switch yet another Maf and it is running better, the rpms are a little wavey but it is holding. I cleared the comp and no problems so far. I'm keeping my fingers crossed

Ok, guess they possibly got a bad bunch of MAF Sensors.

Keep me posted.

The problem came back after 80 miles, I heard it could be a air filter problem that has oil or something in it. The air filter is very clean but I am running out of ideas. Does this sound plausible?

Ok, the filter they are talking about is the K & N Filters, they are reusable filters, you clean them every so often with a K & N Cleaner and there is an Oil that you spray on the filter. These filters have been known to cause problems with some MAF Sensors because of the Oil.

If you happen to be using a K&N Filter try putting a standard air filter in it.

Ok, I need to do some check.... but I was just reading through some more of the info I have and possible causes. And there is mention of 2 relays for the MAF - One provides power and one for the burn-off cleaning cycle. This is on Bosch MAF's.

Ok, so sorry for the late response but have been busy with school. The problem has been off and on. While trying to get a new air filter the car stalled out and wouldn't start. I thought it was done but then a minute or so later I tried to start it and it started and got me to the auto parts store. I got to the store cleaned the mass air flow sensor, changed the filter, and then reconnected the negative wire. I think it was just the fact that the battery was disconnected but the check engine light went off. I made it back home with no problems and then parked it. I came back out a hour later and then let it run at idle for 5-10 minutes or so and everything seemed fine. I was starting to celebrate that the problem was fixed and the check engine light remained off and then all of a sudden and quietly the engine shut off. The CEL came back on and the same symptoms came back on. I disconnected the negative cable till the check engine light went off again and let it run for a while and then the same thing happened and every time i started it after that the same seemingly MAF symptoms occurred.

So tomorrow I am going to try and drive it 7 miles to the closest place I can get someone to pull the code. It is a bosch MAF, I'm pretty sure, and here is a link to one that looks like the one I got, http://www.autopartswarehouse.com/sku/Subaru/Impreza/Bosch/Mass_Air_Flow_Sensor/1998/L/4_Cyl_2-dot-2L/W0133-1598555.html?tlc=Engine+%26+Drivetrain&intcmpid=

So I have been thinking it may be a bad ground but it looks fine. I thought maybe it could be the iacv again because it only stalls out when the engine heats up and the rpms lower. But I don't know if that makes sense for why after I start it again it shows mass air flow sensor problems happen. I was also wondering if the TPS could have anything to do with it, I had it go to a mechanic a while back for something else and he said the TPS needed to be tuned. The car does stay on if I keep my foot on the accelerator while idling.

Does the 2 relay idea still seem valid and I should try and change the wires and put a new harness on? I am going to a autozone so if the code comes up mass air flow sensor I'll get a new one with the warranty but I don't know if it is worth it if there is a different problem causing it.

I talked to a guy at autozone last month and he said I would be surprised how many of the refurb MAF sensors come back. I don't know if that is the problem and I need to try and find a new one or something but any ideas would be appreciated.

Ok, cannot find a test for checking the TPS with a Volt Meter. The only test is with a scan tool that can read Throttle Angle and Voltage. If you can find one to use the voltage should be between 0.45 - 0.55 at O degree Throttle Angle with key in on position not running. If out of spec then just loosen screws and adjust to spec.

Also, the computer could still be bad, I have come across a few that were bad and it only affecting one sensor.

So I don't think the tps would be shorting out my MAF right? I can live with it untuned, but the about computer is there a test I could do to see if it is bad, a ecu isn't cheap so it would not be worth me just replacing and seeing if it is bad? Also would a bad ecu cause this kind of problem? I went to auto zone and I got a P0102 code this time, low input MAF as opposed to high input. Also searching online would a wire harness be more likely in this situation? Or is the fact two different codes more symptomatic of the computer? I have a new maf in and the problem has disappeared but I have a feeling it will be back

Testing

DTC P0102 (QA_LOW): MASS AIRFLOW (MAF) SENSOR CIRCUIT LOW INPUT

1.Turn ignition off. Connect scan tool. Start engine. Observe display for mass airflow and voltage signal values from MAF sensor. If values are between 1.3 g/sec and 250 g/sec or .3-5.0 volts, system has returned to normal. Check circuit between PCM and MAF sensor for intermittent opens or shorts, or PCM and MAF sensor connectors for poor contact. If airflow is not within specifications, go to next step.

2.Start and idle engine. Using voltmeter connected to ground, measure voltage (backprobe) at PCM connector terminal No. 5 (Pink/Blue wire on Forester and Impreza, or White wire on Legacy). If voltage reading is less than .3 volts, go to next step. If voltage reading is more than .3 volts, wiggle PCM connector. If voltage reading changes to less than .3 volts, check PCM connector for poor contact.

3.Turn ignition off. Disconnect MAF sensor. Turn ignition on. Measure voltage at MAF connector terminal No. 1 (Yellow/Green wire on Forester and Impreza, or Yellow/Blue wire on Legacy). If voltage reading is more than 10 volts, go to next step. If voltage reading is 10 volts or less, repair open circuit between main relay and MAF sensor.

4.Turn ignition off. Disconnect PCM. Check resistance of harness between PCM connector terminal No. 5 and MAF connector terminal No. 4 (Pink/Blue wire on Forester and Impreza, or White wire on Legacy). If resistance is one ohm or less, go to next step. If resistance is more than one ohm, repair wiring or poor connection.

5.Measure resistance of harness between PCM connector terminal No. 53 and MAF connector terminal No. 3 (Black/Green wire on Forester and Impreza, or Pink wire on Legacy). If resistance is one ohm or less, go to next step. If resistance is more than one ohm, check for open in harness between PCM and MAF sensor or for poor contact at PCM or MAF sensor connectors.

6.Check resistance of harness between ground and PCM connector terminal No. 5 (Pink/Blue wire on Forester and Impreza, or White wire on Legacy). If resistance is more than one megohm, replace MAF sensor. If resistance is one megohm or less, repair short in ground circuit between PCM and MAF sensor.

DTC P0103 (QA_HI): MASS AIRFLOW (MAF) SENSOR CIRCUIT HIGH INPUT

1.Turn ignition off. Connect scan tool. Start engine. Observe display for mass airflow and voltage signal values from MAF sensor. If values are between 1.3 g/sec and 250 g/sec or .3-5.0 volts, system is normal. Check for poor connections or intermittent open circuits. If values are not within specifications, go to next step.

2.Turn ignition and scan tool off. Disconnect MAF sensor. Turn ignition and scan tool on. Observe display for mass airflow and voltage signal from MAF sensor. If values are less than 250 g/sec or 5.0 volts, replace MAF sensor. If values are greater than 250 g/sec or 5.0 volts, check for short to power in harness between MAF sensor and PCM. After repairing short, check PCM operation and replace if necessary. Retest system.