Still struggling with MAF Sensor type issues

[rprieto]

Regarding my 2002 986S / Tiptronic / 89K Miles

So I've replaced the MAF Sensor and the Air-Oil-Separator (AOS). The MAF Sensor wiring seems to be good and the Durametric SW is recording changes at various RPMs. The car ran well for < 100 miles but today the engine missed here and there on my way to work. The CEL came on on my way home.

Durametric SW indicates P0107, P0102, P1130, and P1128. I've just received the Durametric SW and I'd like to wiggle the MAF sensor connector with the engine using live data to determine if I have an intermittent connection.

Ambient pressure records an unchanging "980" throughout my brief test period at various RPM ranges. (I don't know if that is good or not but a value is recorded).

Let me know if need to capture something else with the Durametric SW to share.

Thanks for the help in advance.

Edited January 9, 2009 by rprieto

[tholyoak]

Ambient pressure sensor is in the DME. P107 is a short to ground.

Procedure is to clear the error, rescan, if the error is still present, replace the DME.

-Todd

Edited January 9, 2009 by tholyoak

[rprieto]

Any idea if why all these codes are tied together? P0107 is a new one for me. The others are MAF related and it is new (Sunset).

I was babying the car for a couple of days but got on the throttle turning left. Came to an idle then the engine missed briefly.

[Loren]

What was the part number of the MAF you put in?

[Elliottc26]

Any idea if why all these codes are tied together? P0107 is a new one for me. The others are MAF related and it is new (Sunset).

I was babying the car for a couple of days but got on the throttle turning left. Came to an idle then the engine missed briefly.

Hi, I have a 3.2S Boxster (2000) and am also having MAF problems...is your engine misfiring? Mine was doing that, so, I disconnected the MAF and the misfiring stopped. I replaced the MAF with a new one today and now the engine idles between 600 - 800 RPM (needle bounces between) and I have found oil on the rear bumper!! The car stalls often when returning to idle from speed; but the power goes on smooth and no misfiring!! I am at my wits end...also the exhaust gases smell different.

I think you can clear the CEL by disconnecting the battery (via negative) for a few seconds to get new codes if it comes on again. I may try that then get it tested...(not forgetting radio code!!)...

[wvicary]

It could be a wiring problem to the MAF sensor, you'll need to do a pinpoint test between the ECU and MAF.

[rprieto]

"986 606 125 01" This matches what I removed.

Car ran perfectly for a few days. I am just starting to run a few Durametric tests.

Prelim test (2 days ago) indicate MAF to produce values 15-20 at idle (~700 RPM).

Values are around 50 at about 2500 RPM.

[m60kaf]

did both sensors have the diode like thing on the side . i changed one for the right part number but without the diode thing. ran bad and had the additional error code. soldered the old diode on the connectors on the side and worked perfect.

One of the annoying things of porsche ownership is there seems to be so many different parts for one app and porsche just progam it for the difference --- we cant do that

[rprieto]

It could be a wiring problem to the MAF sensor, you'll need to do a pinpoint test between the ECU and MAF.

I've not done a pinpoint test from the ECU. I measured voltages that appear to be valid before . Besides, Duramentric is measuring MAF sensor values.

[rprieto]

did both sensors have the diode like thing on the side . i changed one for the right part number but without the diode thing. ran bad and had the additional error code. soldered the old diode on the connectors on the side and worked perfect.

One of the annoying things of porsche ownership is there seems to be so many different parts for one app and porsche just progam it for the difference --- we cant do that

I am using the correct MAF sensor. Both old and new have a diode.

[rprieto]

Funny thing. The CEL cleared itself. I wiggled the MAF sensor while capturing live data w/o a glitch. Drove around for a bit and the car twice hesitated from zero throttle. Just before the car hesitated I was hard on the throttle moments before.

Wondering if there is a leak? Surely this is difficult to find if so.

[rprieto]

I captured both the MAF and the RPM while the car was parked, engine cold (accounts for slightly higher RPM at start).

I noticed fluctuation of the MAF. Is this normal? Later today or tomorrow I want to capture live driving data to look to see if I can capture any engine stutter.

[rprieto]

I captured these live values on my way to work. Stop & Go traffic and the car stalled when I got off the onramp (Tiptronic btw).

The first chart focuses on spikes I see to Zero for the MAF Sensor. (236 to 283 range of the 2nd chart) You can see multiple places where the "Hot Film MAF" goes to Zero. (BTW: The "Mass Air Flow", not the sensor, I see fluctuates from values similar to the "Hot Film MAF" to values in the 200 to 300 range when the "Hot Film MAF" hits Zero. MAF Sensor Voltages, mostly seen in the 1.xx to 2.xx range, also goes to near Zero in sync with the Hot Film MAF values.

The second is the whole sequence for reference.

The third is what happened when I got off the freeway and the engine shut off. Looks like all data capturing stopped as well. Restarted the car and pulled over to disconnect the MAF sensor connector to get me to work.

Does this hint to a possible wiring issue?

Edited January 13, 2009 by rprieto

[Boxsterund914]

As I'm sure you know, sometimes things are not what they seem. I had what I thought were MAF and/or Air Oil Seperator (AOS) issues and they were neither one. The car was blowing a cloud of smoke on start-up and running rough.

It turned out that the oil filler hose that goes from the rear trunk wall (hooks on to the oil filler at the coolant reservoir tank and goes to the oil fill point on top of the engine) had cracks in the accordian section of this tube that were not visible. Oil filled fine because the cracks were on the top of this tube. I chased this problem thinking it was a faulty AOS and when I was under there fiddling arouind I must have cracked the oil fill tube all the way through because the next time I added oil it just poured onto the ground.

The filler tube was easy to replace and cheap. Car runs perfectly now. I'm not saying that this is your problem, just saying that these problems sometimes need to be chased around.

[Elliottc26]

As I'm sure you know, sometimes things are not what they seem. I had what I thought were MAF and/or Air Oil Seperator (AOS) issues and they were neither one. The car was blowing a cloud of smoke on start-up and running rough.

It turned out that the oil filler hose that goes from the rear trunk wall (hooks on to the oil filler at the coolant reservoir tank and goes to the oil fill point on top of the engine) had cracks in the accordian section of this tube that were not visible. Oil filled fine because the cracks were on the top of this tube. I chased this problem thinking it was a faulty AOS and when I was under there fiddling arouind I must have cracked the oil fill tube all the way through because the next time I added oil it just poured onto the ground.

The filler tube was easy to replace and cheap. Car runs perfectly now. I'm not saying that this is your problem, just saying that these problems sometimes need to be chased around.

I have found that connecting the MAF, a new one, the car had problems with idle, acceleration...was due to a faulty 02 sensor so both cause an issue if one not working...disconnecting the MAF ironed out the problem...am having new 02 sensor fitted Tuesday

[rprieto]

As I'm sure you know, sometimes things are not what they seem. I had what I thought were MAF and/or Air Oil Seperator (AOS) issues and they were neither one. The car was blowing a cloud of smoke on start-up and running rough.

It turned out that the oil filler hose that goes from the rear trunk wall (hooks on to the oil filler at the coolant reservoir tank and goes to the oil fill point on top of the engine) had cracks in the accordian section of this tube that were not visible. Oil filled fine because the cracks were on the top of this tube. I chased this problem thinking it was a faulty AOS and when I was under there fiddling arouind I must have cracked the oil fill tube all the way through because the next time I added oil it just poured onto the ground.

The filler tube was easy to replace and cheap. Car runs perfectly now. I'm not saying that this is your problem, just saying that these problems sometimes need to be chased around.

I have found that connecting the MAF, a new one, the car had problems with idle, acceleration...was due to a faulty 02 sensor so both cause an issue if one not working...disconnecting the MAF ironed out the problem...am having new 02 sensor fitted Tuesday

What were the codes? Only today will I have time to get to this.

Based on the graph I posted, I would think it to be more wire/connector related due to the rapid drops in voltage or MAF values seen. I don't want to event think about the DME. That and the whole engine wire harness are over $1K each. I am hoping to find an exposed wire rubbing against the car body or simply a bad connection at the MAF sensor itself. If not, I will disconnect the DME harness at the DME and reconnect. Did not seem easy when I was looking into that area last week. I'll also clean the MAF Sensor connector (connections) as well.

[Elliottc26]

As I'm sure you know, sometimes things are not what they seem. I had what I thought were MAF and/or Air Oil Seperator (AOS) issues and they were neither one. The car was blowing a cloud of smoke on start-up and running rough.

It turned out that the oil filler hose that goes from the rear trunk wall (hooks on to the oil filler at the coolant reservoir tank and goes to the oil fill point on top of the engine) had cracks in the accordian section of this tube that were not visible. Oil filled fine because the cracks were on the top of this tube. I chased this problem thinking it was a faulty AOS and when I was under there fiddling arouind I must have cracked the oil fill tube all the way through because the next time I added oil it just poured onto the ground.

The filler tube was easy to replace and cheap. Car runs perfectly now. I'm not saying that this is your problem, just saying that these problems sometimes need to be chased around.

I have found that connecting the MAF, a new one, the car had problems with idle, acceleration...was due to a faulty 02 sensor so both cause an issue if one not working...disconnecting the MAF ironed out the problem...am having new 02 sensor fitted Tuesday

What were the codes? Only today will I have time to get to this.

Based on the graph I posted, I would think it to be more wire/connector related due to the rapid drops in voltage or MAF values seen. I don't want to event think about the DME. That and the whole engine wire harness are over $1K each. I am hoping to find an exposed wire rubbing against the car body or simply a bad connection at the MAF sensor itself. If not, I will disconnect the DME harness at the DME and reconnect. Did not seem easy when I was looking into that area last week. I'll also clean the MAF Sensor connector (connections) as well.

I had codes P0134 and P1126 all to do with the 02 sensor in Bank 1 (right hand side of car)...only codes I had...

[rprieto]

:( - Still no improvement!

1) I did a point to point on the MAF Sensor using the wiring diagrams on the Bentley book and all connections are perfect.

2) Reseated the DME connections hoping that might also clean any intermittent connections.

3) I ran the car with the MAF Sensor plugged in around the block. I noticed the rotten-egg smell probably due to a little too much for the catalytic converter. I decided to capture some of those values at the O2 sensors. By the way, there is no foul odor with the MAF sensor disconnected after returning from a test drive.

4) I re-ran 2 sets of driving test both with and without the MAF sensor plugged in and captured some data. Never once did I see the MAF sensor go to zero like I did before. However, I noticed voltages on the O2 sensors go to zero both with and without the MAF sensor plugged in. (Yes, I disconnect the battery after any changes are made to the MAF Sensor to reset everything.)

As before, the car runs MUCH better with it UNPLUGGED! Can a disconnected MAF mask some other failure I am missing?

Please help!

Edited January 19, 2009 by rprieto

[JeTexas]

I believe that with the MAF unplugged the DME is reading the oxygen sensor values and adjusting the fuel/air mixture solely by that. If your new MAF is under warranty, I'd try exchanging it.

[Loren]

I believe that with the MAF unplugged the DME is reading the oxygen sensor values and adjusting the fuel/air mixture solely by that. If your new MAF is under warranty, I'd try exchanging it.

Yes, the car sill start, idle fine and run pretty well up to 4000 RPM with no MAF.

[tholyoak]

Do you still have the P0107 code? If you do and you clear it and it reappears, the DME is bad and must be replaced.

-Todd

[rprieto]

Do you still have the P0107 code? If you do and you clear it and it reappears, the DME is bad and must be replaced.

-Todd

P0107 code has never reappeared. Must a have been a fluke.

[rprieto]

I believe that with the MAF unplugged the DME is reading the oxygen sensor values and adjusting the fuel/air mixture solely by that. If your new MAF is under warranty, I'd try exchanging it.

This IS my second MAF sensor from Sunset. I sent the first one back and am still out $$$ till Bosch refunds Sunset.

BTW: I did see 2 spots and only for one brief spot at 2 very different time slots where the Hot Film MAF went to zero. Idle values of the Hot Film MAF seem kinda high (24-37 range at 600-800 RPM).

Hot Film MAF is seen in the 200 range at less then 3000 RPM. I've no comparison data so I don't now if this is normal. I was up pretty late last night messing with this to no avail. Unplugged the MAF and there the car sits for yet another day...

Edited January 19, 2009 by rprieto

[Elliottc26]

I believe that with the MAF unplugged the DME is reading the oxygen sensor values and adjusting the fuel/air mixture solely by that. If your new MAF is under warranty, I'd try exchanging it.

This IS my second MAF sensor from Sunset. I sent the first one back and am still out $$$ till Bosch refunds Sunset.

BTW: I did see 2 spots and only for one brief spot at 2 very different time slots where the Hot Film MAF went to zero. Idle values of the Hot Film MAF seem kinda high (24-37 range at 600-800 RPM).

Hot Film MAF is seen in the 200 range at less then 3000 RPM. I've no comparison data so I don't now if this is normal. I was up pretty late last night messing with this to no avail. Unplugged the MAF and there the car sits for yet another day...

How frustrating!! I take it your 02 sensors work perfectly? I think by now I would be seriously considering letting Porsche run a diagnostic and see what they think...

[JeTexas]

I can run a diagnostic with the fields you need to compare and send it to you, but I have a 3.4 996, so it won't be an exact match.