P0101 Maf Code

[ThomS]

If you are getting this code and I understand that it is a MAF code and taking out the screen does nothing and then replacing the sensor it self ans still getting this code, What else can cause this any ideas?
A/F numbers I have been told are good and vacuum is good.

[lowboy72]

I am getting this code as well. P0101 and P0121. About 500 miles inbetween the first and second. About 100 miles between the second and third. I am concerned as this is a new install since Saturday and I took special care in handling the sensors. How many others are experiencing this problem?

[ThomS]

What year car do you have? have you taken out the MAF screen yet?
Also check you TP connection. I put new MAF and and new PC Pro for the fifth injector and that seemed to solve my problmes.

[Kyp J]

I am getting this code as well. P0101 and P0121. About 500 miles inbetween the first and second. About 100 miles between the second and third. I am concerned as this is a new install since Saturday and I took special care in handling the sensors. How many others are experiencing this problem?

Look at this thread.

http://www.fastforwardsuperchargers.com/forum/showthread.php?t=691&page=2k

The manual excerpt at post 16 on page 2 gives the ECM parameters for setting them. I still think jumping on the throttle under 2000 rpm is what causes it. Wait till revs are up a bit before going into boost. The TPS signal is forced to WOT as soon as boost is seen. This makes the ECM think more air should be there. (I think)

I haven't gotten it since I modified my driving practices.

[Tom @ Fast Forward]

For what it's worth, I climb on my cars below 2000RPM all the time. Too lazy to down shift. :) I have also recently learned that, if you oil the life out of the air filter, the incoming air will suck in the oil and coat the MAF wire. That can also be a cause of the codes. If you oil the Air Filter, do it with a very light spray of K&N oil.

[lowboy72]

Look at this thread.

http://www.fastforwardsuperchargers.com/forum/showthread.php?t=691&page=2k

The manual excerpt at post 16 on page 2 gives the ECM parameters for setting them. I still think jumping on the throttle under 2000 rpm is what causes it. Wait till revs are up a bit before going into boost. The TPS signal is forced to WOT as soon as boost is seen. This makes the ECM think more air should be there. (I think)

I haven't gotten it since I modified my driving practices.

I have seen this thread. It seemed to revert to troubleshooting a P0171 code over the others. I also read the diagnosis for the P0101 and P0121 codes. I seen that someone mentioned the TPS and the MAF sensor share a ground. Is there anything else that they share in regards to functionality? I find it very curious that I trip these codes simultaneously although they seem to me to have different functions.

As a side note I did not receive these codes until I fixed the binding bypass actuator arm.

My Miata is a 2002.

[Kyp J]

As a side note I did not receive these codes until I fixed the binding bypass actuator arm.

My Miata is a 2002.

With a binding bypass were you able to get it into boost below 2000 rpm?

As far as driving style is concerned and whether it is causing codes, it is hard to determine absolutely since there seem to be a lot of variables from one car to another, or even in ECM differences between model groups (as in 99-00 vs. 01-05 etc). Even the VVT code that spawned a TSB from Mazda seems to be a variable within the 01-02 ECM programming details.

As cars get older, any variations probably increase that might show up under extreme conditions in one car and not another.

Until someone accidentally proves a specific cause and effect for some of these things, you have to make up something that seems to work. Kind of like how Religions were formed (And how they all diverged from common roots into various factions killing each other, but that is on Mnet, not here.)

[lowboy72]

So I went back to the other thread and looked for commonality between the two codes. Both codes have the same error handler with low MAF signal or with the throttle position at 50%+ if the MAF signal is low.

So it can be only one of two things; low air flow or that the throttle is getting stuck open.

I was having a problem with a stuck throttle this weekend as well. I thought that it might be because I had the throttle cable too tight after making the idle adjustments. It no longer binds after easing tension on the cable, but I do notice that sometimes the RPMs still hang high (between 1500 to 2000 RPM) when I disengage the clutch. So personally I am leaning more towards a throttle body issue over the MAF and will work on that first. If it seems to be fine I will remove the screen. If either one does not work I will replace the sensors.

[Kyp J]

On some of the newer kits there was an issue with the Throttle position sensor adapter or something that was causing a binding throttle plate. I don't know if there are differences in the various kits or if that has been fixed, but search on "TPS" and you might find it to see if it might apply. It has a simple repair if it is the problem. Does it seem like it is binding when you operate it by hand?

[Kyp J]

Trying to delete this because I was wrong about the "sticky" in the 94-97 thread TPS problem. Wrong problem. Look for wrong size hole in TPS.

[ThomS]

Tom the only time I remember me getting these two codes at the same time were when we disconnected some part maybe a vacuum hose on the left side of the engine, remember. By the VTCS I put it back on and they did not come back well,one of them did not. 0121. What was that you remember?
Yes I was the one the put too much oil on the oil filter and coated the MAF sensor. Another lesson learned.

I have seen this thread. It seemed to revert to troubleshooting a P0171 code over the others. I also read the diagnosis for the P0101 and P0121 codes. I seen that someone mentioned the TPS and the MAF sensor share a ground. Is there anything else that they share in regards to functionality? I find it very curious that I trip these codes simultaneously although they seem to me to have different functions.

As a side note I did not receive these codes until I fixed the binding bypass actuator arm.

My Miata is a 2002.

[lowboy72]

So I have been using the Maf code pdf that Tom posted to troubleshoot my problem. I had a code reader but never plunked down the change for a scanner. I bought one and I discovered a big problem. My TPS will sometimes read 100% at partial throttle while cruising. If this condition exists for 5 seconds or longer, I meet both of these conditions:

P0121:

If PCM detects that throttle valve opening angle is above 50% for 5 s after following conditions are met,
PCM determines that TP is stuck open:
MONITORING CONDITION
— Engine speed above 500 rpm
— MAF sensor signal below 5.3 g/s {0.7 lb/min}

P0101:

If mass intake-air flow amount is for below 5.3 g/s {0.70 lb/min} for 5 s and engine speed is above 500
rpm with engine running, PCM determines that detected mass intake-air flow amount is too low.
MONITORING CONDITION
—ECT is above 70 °C {158 °F}
— Throttle opening angle is above 50%

So if the TPS is sending an errored signal while cruising, (over 50% TP) it will trip both codes. I need a new TPS.

A scanner is a wise investment for any modified car.

[Kyp J]

So I have been using the Maf code pdf that Tom posted to troubleshoot my problem. I had a code reader but never plunked down the change for a scanner. I bought one and I discovered a big problem. My TPS will sometimes read 100% at partial throttle while cruising. If this condition exists for 5 seconds or longer, I meet both of these conditions:

P0121:

If PCM detects that throttle valve opening angle is above 50% for 5 s after following conditions are met,
PCM determines that TP is stuck open:
MONITORING CONDITION
— Engine speed above 500 rpm
— MAF sensor signal below 5.3 g/s {0.7 lb/min}

P0101:

If mass intake-air flow amount is for below 5.3 g/s {0.70 lb/min} for 5 s and engine speed is above 500
rpm with engine running, PCM determines that detected mass intake-air flow amount is too low.
MONITORING CONDITION
—ECT is above 70 °C {158 °F}
— Throttle opening angle is above 50%

So if the TPS is sending an errored signal while cruising, (over 50% TP) it will trip both codes. I need a new TPS.

A scanner is a wise investment for any modified car.

Are you getting the codes frequently? Like every time you see the TPS signal go high?

Do you have a vacuum/boost gauge? I frequently go into boost slightly when I am cruising. For example, going up a slight grade, to maintain 70 MPH or so, it will creep into boost by a few psi. The PC Pro forces the TPS signal high when it sees boost above some small amount (I forget exactly). The conditions also say something about the MAF indicating some specific amount of air. I don't know how to determine that, maybe the scanner would display the MAF voltage while in those conditions. I suspect the values should be way more volume than those specs. If not, maybe the MAF is bad or dirty or wiring or what ever. I think the TPS might be working right. I don't remember if you posted what year it is but I think all NBs are non adjustable.

There have been a lot of reports on Mnet about spraying the MAF sensor with a specific cleaner and the improved performance resulting. If you have an oiled filter, there is a good chance it has gotten some oil on the heated wire. If not, maybe it is just dirty.

[lowboy72]

Are you getting the codes frequently? Like every time you see the TPS signal go high?

Do you have a vacuum/boost gauge? I frequently go into boost slightly when I am cruising. For example, going up a slight grade, to maintain 70 MPH or so, it will creep into boost by a few psi. The PC Pro forces the TPS signal high when it sees boost above some small amount (I forget exactly). The conditions also say something about the MAF indicating some specific amount of air. I don't know how to determine that, maybe the scanner would display the MAF voltage while in those conditions. I suspect the values should be way more volume than those specs. If not, maybe the MAF is bad or dirty or wiring or what ever. I think the TPS might be working right. I don't remember if you posted what year it is but I think all NBs are non adjustable.

There have been a lot of reports on Mnet about spraying the MAF sensor with a specific cleaner and the improved performance resulting. If you have an oiled filter, there is a good chance it has gotten some oil on the heated wire. If not, maybe it is just dirty.


The scanner log showed that for a 5 second interval the TPS was at 100% with a MAF reading between 4.62 and 4.74. I was cruising with very little throttle at the time (between 2k to 3k RPM). The throttle should have read probably between 10 and 15%. This will cause the ECU to trip a pending code for P0101 and P0121 because the MAF reading was low in combination with a high TPS (above 50%).

There is a chance that that the MAF sensor may be reading low. According to the .pdf that Tom provided I should be over 5.3g/s above 500 RPM. I did not oil the filter and I do not know why it is reading kind of low and I have not tested the circuit (I hate taking off the splash plate). But for now I will focus on the TPS issue since the scanner showed the error.

[Kyp J]

I asks again: Do you have a boost gauge?

[Kyp J]

Also, I have no idea about MAF voltages but if you were to look at the voltage at idle and again at high rpm there might be a range that might be interpreted to see what is a fair amount of air (cruising) versus a tiny bit of air (idle) and what the voltages are. I tried looking up MAF voltages and didn't immediately find anything useful.

[lowboy72]

I asks again: Do you have a boost gauge?

I have a vacuum boost gauge. But boost has nothing to do with it. I am completely out of boost when I trip the codes. Please take a look at my posts again and review the part where I use a scanner to record my MAF, TPS and RPM values while driving. The scanner converts voltage to airflow. My car idles at around 2.9g/s, cruises between 4.5 and 6g/s and is at about 140g/s wide open throttle. Tom tells me that it is practically impossible for the PC Pro to continue to send a signal out of boost. So now I am going to look closely at the wiring on the PCM.

This has turned into a straight-up thread hi-jack. Sorry.

[ThomS]

Please do not be sorry at all. I am learning a lot by what I am reading...
Thanks

[lowboy72]

Well, I have figured out how to make it happen. It is intermittent but it works. I go WOT up to near redline, release acclerator and clutch in. Even with the accelerator released, it shows 100% TPS. I know the throttle is actually not stuck open because the RPMs drop. Here is a log from the scanner for those who are interested:

MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 3758
MAF FLOW GR/SE 3.94
COOLANT �F 181

Frame 62 Time 62.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 2189
MAF FLOW GR/SE 3.12
COOLANT �F 181

Frame 63 Time 63.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 1275
MAF FLOW GR/SE 3.08
COOLANT �F 181

Frame 64 Time 64.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 1035
MAF FLOW GR/SE 3.01
COOLANT �F 181

Frame 65 Time 65.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 1115
MAF FLOW GR/SE 2.99
COOLANT �F 181

Frame 66 Time 66.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 1092
MAF FLOW GR/SE 3.06
COOLANT �F 181

Frame 67 Time 67.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 1105
MAF FLOW GR/SE 2.99
COOLANT �F 181

Frame 68 Time 68.8


MIL STATUS OFF
ABSLT TPS % 100.0
ENG SPEED RPM 1094
MAF FLOW GR/SE 3.17
COOLANT �F 181

Frame 69 Time 69.8

The last four frames show it is practically idling and the TPS still shows 100%. Final resolution will have to wait until I get a buddy to look at a volt meter while I drive the car. I need to find out where the naughty signal originates.

[Tom @ Fast Forward]

Next thing might be to remove the SC belt and tie open the bypass and remove the PC-Pro harness. See if it still happens. That will eliminate the PC-Pros from the TPS circuit. The PC-Pro should release the TPS as soon as you drop below 1PSI and that shouldn't take any 5 seconds.

[Kyp J]

Sorry, I never saw where you mentioned boost at all and I thought the statement "...with a MAF reading between 4.62 and 4.74..." was refering to voltage. Didn't know it was g/s. I haven't gotten into a scan gauge far enough to know what it displays. If you aren't in boost my theories are toast.

I'm out of ideas.:gnorsi:

[lowboy72]

I just took off the belt and ran without the PC Pro. I could not reproduce the problem. As soon as I let off the throttle the scanner showed 0% throttle, time and time again. Now I am positive that my PC Pro continues to send a signal for a few seconds out of boost.

[Kyp J]

I just took off the belt and ran without the PC Pro. I could not reproduce the problem. As soon as I let off the throttle the scanner showed 0% throttle, time and time again. Now I am positive that my PC Pro continues to send a signal for a few seconds out of boost.

Kink in vacuum/boost tube to pc pro?

[lowboy72]

I called Tom and we troubleshooted together over the phone. It turns out that the PC Pro continues to send voltage on its TPS out wire even when out of boost. I can even completely disconnect the factory TPS sensor and the ECU will still show 100% TPS. I have returned the unit back to Tom for repair/replacement.

[ThomS]

I called Tom and we troubleshooted together over the phone. It turns out that the PC Pro continues to send voltage on its TPS out wire even when out of boost. I can even completely disconnect the factory TPS sensor and the ECU will still show 100% TPS. I have returned the unit back to Tom for repair/replacement.
What was the resault of this action?

[Tom @ Fast Forward]

A new thought. Does this happen while driving or on the first couple minutes of cold start?

[Tom @ Fast Forward]

On your car it did but not on any others that I know of.

Thom, if you can put a voltmeter from the Pur/Yel wire on the main PC-Pro and ground, you can check that on your car. On his, it would go high under boost and stay there. I even tested the one in my 05 and sent him the full harness to try. No problem in my 05. Held high in his car. ??????


I called Tom and we troubleshooted together over the phone. It turns out that the PC Pro continues to send voltage on its TPS out wire even when out of boost. I can even completely disconnect the factory TPS sensor and the ECU will still show 100% TPS. I have returned the unit back to Tom for repair/replacement.

[ThomS]

A new thought. Does this happen while driving or on the first couple minutes of cold start?

It happens while driving. It takes about 50 + miles.

[ThomS]

On your car it did but not on any others that I know of.

Thom, if you can put a voltmeter from the Pur/Yel wire on the main PC-Pro and ground, you can check that on your car. On his, it would go high under boost and stay there. I even tested the one in my 05 and sent him the full harness to try. No problem in my 05. Held high in his car. ??????


I think you already know the answer to that.. I will think about it.

I did a real stupid thing yesterday. After I checked the new codes the way you have to with the code reader, I was so mad on what I saw, I just came into the house told my wife and starting reading about the codes on the computer and left everything as it was. All last night and most of the day. Yep you guessed it I now have a totally dead battery.
Can one person do anything any more stupid then that. Don't answer that.
So right now I can not check anything.. No Volts at all to check.....

Dumb Dumb dumb dumb dumb dumb dumb dumb dumb dumb
:stupid:

[lowboy72]

Sorry that I have not updated my situation. It is very bizarre and after much troubleshooting have come to determine that I have a periodic signal irregularity that causes the PC Pro TP intercept to hang. This event is caused by going WOT at any RPM and then immediately clutching in and letting the RPMs drop all the way to idle. Once the RPMs reach near idle, with the clutch in, the RPMs will jump from 850-900 to around 1500 RPM. The scanner will show 100% TPS and the PC Pro signal output wire will show 100% TPS voltage even though the input wire from the ECU is at idle voltage. A simple blip of the throttle will "wake" the PC Pro back up and the TPS voltage intercept will function normally. This event, if longer than five seconds, will cause a P0101 and P0121 code. It is intermittent, but nonetheless easily reproducible.

But I can drive around it and have done so successfully for close to 1000 miles. I simply do not hold the clutch in while braking. For some reason allowing the drivetrain to gradually drop the RPM prevents this condition. So as long as I adhere to this driving tactic, my car is happy and code free.

[maggie]

Good diagnosis. Would the higher vacuum from decelerating in gear (engine braking) be a factor?

[Tom @ Fast Forward]

It's strange because we do that all the time on the dyno. Run to redline and push in the clutch and lift off the gas at the same time.

[lowboy72]

Good diagnosis. Would the higher vacuum from decelerating in gear (engine braking) be a factor?

If it is a factor, it would be a factor in preventing the issue. Something about engine braking prevents the problem from occuring. I have come to the conclusion that it is something electrical and I have tried to think of some components whose signal would vary considerably between WOT and idle and operates in tandem with throttle position. The crankshaft position sensor is next on my hitlist. But besides that, whatever the signal condition is that causes the PC Pro to freeze, it occurs only on my car. Furthermore this rogue signal is not out of tolerance of voltage for any sensor input to the PCM. Because of this I have been ripping my hair out trying to resolve the problem.

[ThomS]

Well this all sound very similar and now I am thinking it is not only happing on your car.

[lowboy72]

Well this all sound very similar and now I am thinking it is not only happing on your car.

I looked at the other thread and do not think it is the same issue. The P0171 code is for your fuel system running lean. The P0101 and P0121 are indicators of conditions triggered by air volume. So I think it is your MAF and here is why:

First you take your three codes and look at like conditions:

P0101 - PCM compares actual input signal from MAF sensor with expected input signal from MAF sensor which
PCM calculates by engine speed.
• If mass intake-air flow amount is above 74.7 g/s {9.88 lb/min} for 5 s and engine speed is below 2,000
rpm with engine running, PCM determines that detected mass intake-air flow amount is too high.
• If mass intake-air flow amount is for below 5.3 g/s {0.70 lb/min} for 5 s and engine speed is above 500
rpm with engine running, PCM determines that detected mass intake-air flow amount is too low.

P0121 - • If PCM detects that throttle valve opening angle is below 12.5% for 5 s after following conditions are met,
PCM determines that TP is stuck close:
MONITORING CONDITION
— ECT is above 70°C {158°F}
— MAF sensor signal above 63.2 g/s {8.36 lb/min}
• If PCM detects that throttle valve opening angle is above 50% for 5 s after following conditions are met,
PCM determines that TP is stuck open:
MONITORING CONDITION
— Engine speed above 500 rpm
— MAF sensor signal below 5.3 g/s {0.7 lb/min}

P0171 - PCM monitors short term fuel trim (SHRTFT) and long term fuel trim (LONGFT) values when the
monitoring conditions are met or the DRIVE MODE 1 is run. If fuel trim exceeds preprogrammed criteria,
PCM determines that the fuel system is too lean.

THe P0101 and P0121 are tripped because your MAF sensor is indicating that airflow is too low. But in actuality it is fine. The PCM trusts the MAF and starts to trim fuel to compensate. This then causes a lean condition and over time this lean condition will trigger the P0171.

So to verify this I would let the engine idle for about 20 minutes and then execute a drive cycle while logging your O2 voltage, short and long term fuel trims, and MAF voltage. I would pay real close attention to your MAF sensor flow, especially at idle. If it is below the tolerance above I would run through the troubleshooting steps described for one of the MAF codes. The P0171 troubleshooting is specifically for additional air after the MAF which inadvertently leans out the mixture.

Or you could be experiencing my problem and may either have a valve cover leak, a poor seal on a sensor on the head or block, a clogged fuel filter or a bad fuel pump.

[ThomS]

I thank you for your time to type all that up and it has given me a lot to think about and a better place to start working or have that work done.
I thank you very much for your time. I especially like that very last part ? I was doing really well tell then. And still am. One question, If I am running too lean beacuse of this condition then wouldn't it show up on the A/F gauge ? If it doesn't, it has been between 13.9 and 15.9
pretty steady, except when I go into boost ? Does it only take 5s to test and give that code too? 0171.

[lowboy72]

I thank you for your time to type all that up and it has given me a lot to think about and a better place to start working or have that work done.
I thank you very much for your time. I especially like that very last part ? I was doing really well tell then. And still am. One question, If I am running too lean beacuse of this condition then wouldn't it show up on the A/F gauge ? If it doesn't, it has been between 13.9 and 15.9
pretty steady, except when I go into boost ? Does it only take 5s to test and give that code too? 0171.

Stoic is 14.7. Readings between 13.9 and 15.9 at idle is pretty much normal until the engine warms up. Then it should be within a couple tenths of a point +/- of 14.7. The last part was to indicate that an air leak before the front 02 would throw off the front 02 readings. This unmetered air would not be compensated for by the PCM and could cause a lean condition. Or that either the MAF, Front O2 or both are not functional. What I would do is follow the troubleshooting steps for the P0171 defined in the maf codes pdf provided by Tom. Most of the troubleshooting requires a scanner and I would focus specifically on troubleshooting the MAF and the Front O2 sensor. They are the most likely culprits for causing the PCM to believe that there is a lean condition even though your A/F meter reads fine.

[ThomS]

Thanks so much. for everything.. Lowboy72

[Tom @ Fast Forward]

I sent a note off to Moss and Dobeck about the TPS and the codes. Asking them if they had any idea why the output voltage might "hang". I will let you know what I hear.

[ThomS]

Lowboy72 I just wanted to keep you informed that the MAF sensor in this car, I just found out is brand new. Kenjitsu Auto put a new one in when
I had some work done by them in June. I am taking the car back to them
Saturday. The car still runs great A/F # and vacuum # are good.


Tom let me know if you get an answer from Moss. Thanks for all you doing to fig this out.
This is a great forum always find help from someone.

[lowboy72]

Personally I am more concerned for the P0171 than the P0101 and P0121. I am curious if the voltage range on the front O2 is indicating rich even though it is not.

[ThomS]

I have watched my A/F # even after warm up it runs between 13.9 to 15.9 and I have a new 02 sensor installed.