Re: P0102 - MASS air flow sensor; A low voltage from the sensor to the ECM (DME)...

I fighting an issue and getting the following codes: 1998 Boxster 174K miles 5 speed... all stock

P0102 Mass Or Volume Air Flow A Circuit Low Input
P0157 Oxygen Sensor Circuit Low Voltage Bank 2 Sensor 2
P0305 Cylinder 5 Misfire Detected
P1318 Manufacturer Controlled Ignition System Or Misfire
P1316 Manufacturer Controlled Ignition System Or Misfire
P1317 Manufacturer Controlled Ignition System Or Misfire
There was also a code for the O2 sensor Bank 2 sensor 1 (I didn't write it down)

All 4 O2 sensors are new (less than 4K miles). New plugs. New AOS. Codes came back.

I want to think the MAF is to blame here, but, seems weird that issue is only on Bank 2, misfires in Cylinders 4, 5 & 6, both O2 sensors on same side.

I doubt it is coils as unlikely all 3 go bad same time.

Any thoughts on cause?????

... cylinder-specific misfire is at cylinder 5.
All of the other codes may be dependent on that one.
Check to make sure that the coil pack's connector on 5 is secure.
Happy Boxstering
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

I should have added that I also found these descriptions of the codes specific to a 98. I will check #5 if all looks good will flip Bank 1 coils with Bank 2 coils and see what happens.

Thanks

P1316 Misfire, Cylinder 4, Emission Relevant
P1317 Misfire, Cylinder 5, Emission Relevant
P1318 Misfire, Cylinder 6, Emission Relevant

I switched the coil packs from one side to the other. Car still runs like crap, idle is hunting and idles rough. Codes P0102 & P0157 came right back... no miss fire codes yet but I am sure they will return.

Disconnected MAF no change. Took the oil cap off and she ran even worse.

Not sure what to look at next??????????

... you have an air leak downstream of the Mass Airflow Sensor.
Check the position of the rubber sleeves that connect the tee to the intake Plenums.
With the car idling spray engine starter around the sleeves or anywhere a leak may be happening.
If there is la leak, the engine will rev higher.
Happy Boxstering
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

---

Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

Yea been down this path already... I originally thought it was an air leak and have tried as you suggested with no luck. I sprayed & sprayed nothing. Pulled the TB and connection pieces, cleaned and reinstalled no change, I am out of thoughts on what to look for UGH

Maybe you called it. I just code P1313 Manufacturer Controlled Ignition System Or Misfire- I believe this is bank 1, cylinder 1. I have extra coils here so will replace and see if issue goes away.

I changed coil pack in cylinder 1... started car and within a minute or so CEL flashing with following codes: SO originally all codes were on bank 2- switch coil packs from 1 side to the other now issues are on bank 1. Changing out 1 coil pack made matters worse?????? I am so confused.

P0102 Mass Or Volume Air Flow A Circuit Low Input
P0300 Random - Multiple Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P1314 Manufacturer Controlled Ignition System Or Misfire
P1315 Manufacturer Controlled Ignition System Or Misfire
P1319 Manufacturer Controlled Ignition System Or Misfire

Quote
Ollie
I changed coil pack in cylinder 1... started car and within a minute or so CEL flashing with following codes: SO originally all codes were on bank 2- switch coil packs from 1 side to the other now issues are on bank 1. Changing out 1 coil pack made matters worse?????? I am so confused.

P0102 Mass Or Volume Air Flow A Circuit Low Input
P0300 Random - Multiple Misfire Detected
P0302 Cylinder 2 Misfire Detected
P0303 Cylinder 3 Misfire Detected
P1314 Manufacturer Controlled Ignition System Or Misfire
P1315 Manufacturer Controlled Ignition System Or Misfire
P1319 Manufacturer Controlled Ignition System Or Misfire

so let me see if I can expand upon this a bit and provide some help.

There have been a few -- not many -- cases of misfires arising from a bad MAF. And on one bank too. I'm not sure why this is but I can guess. The failure of the MAF is intermittent and gets in phase/time with the engine and the misfires occur. Now the thing is the phase may not be that steady or regular but when the misfires occur that's all she wrote. The DME doesn't go into some kind of research mode, let's see where this leads us mode, it just flags misfires and that's that.

Also, more cylinders might misfire but when the CEL comes on that's that too. The engine is shut off, the codes read, and the owner is left scratching his head with what he thinks is a complete picture albeit a puzzling picture but it is an incomplete picture.

Before you replace the MAF, have you tried running the engine without the MAF? I just read some older posts and I read where you disconnected the MAF and then removed the oil tube filler cap. You have to be very careful and try one thing at a time. You have to disconnect the MAF, clear DTCs to reset all fuel trims to their defaults, then fire up the engine and give it some time to learn without the benefit of the MAF.

Also, I came into this late -- been dealing with family matters night and day these last 4 days or so and have 3 or 4 more days to go before things (I hope!) settle back down -- so I do not know what you've done or considered but have you considered, is it a possibility, there's bad gas in the tank?



Edited 1 time(s). Last edit at 04/27/2013 06:49PM by MarcW. (view changes)

Ran the tank almost dry, refilled with fresh gas- no change
Disconnected MAF- nothing else, no change
Unscrewed oil cap, nothing else, idled worse

summary to date...
-Throwing P0102 code is a constant
-Multiple misfires on bank2 along with codes indicating low voltage bank2 both sensors P0157, P0151
-Flip coils from bank 2 to bank 1 and miss-fires moved to bank 1 but no O2 sensor codes
-Put coils back into original configuration and miss- fires moved back to bank 2- I moved some of those to the point I thought I had isolated 1 specific bad coil. changed it with an old one I had here but was functioning properly when last used. restarted car and hunting was gone and idle was smooth. took car for 15 mile drive no issues... however still had P0102 code pending.
- cleared all codes and went for 35 mile ride neat morning. car was running great made several stops restarts etc with no issues
- after 35 milers of driving came to a stop and blinking CEl & hunting was back . P0102, P0151, p0157 & a bunch of mis fire codes related to bank2 P0300, 0304, 0305, 0306, 1316, 1317, 1318, 1319
- let the car sit for a few hrs and cleared codes drove home, car ran great no CEl, no misfires, no hunting at idle. 3 pending codes P0102 (always present) P0157 and a new one P0151 Oxygen Circuit No Activity Detected (Bank 2 Sensor 1)
- I don't think MAF as I can move the misfires with the coils. Could be weak coils as things seem to be worse when engine hot. suspect seeing O2 sensor codes due to the misfires and resultant what ever happens to the gases from the miss-fire. BUT- I do have that persistent P0102 code that always comes on almost immediatlely (usually pending for a long time)

Could it be combination of weak (ie old) coils and a bad MAF? Would you change MAF first or coils first. I want to do 1 thing at a time so I can understand

This strongly suggests the MAF is not the cause of the symptoms. It is not 100% conclusive as it is a crude/shade tree mechanic test. But given the cost of the MAF i'd not replace one just yet. IIRC the old MAF may not be available and the newer MAF requires a DME firmware update which costs on top of the MAF.

I did a bit of research and the guidelines for misfires in which there are oxygen sensor fault codes ahead of the misfire fault codes first correct this fault and road test the vehicle.

Thus the problem may lie with the sensors.

Here is the text from my reference:

In the event of a short circuit to B+ or ground in the oxygen sensors ahead of the TWC, the mixture becomes too lean or too rich. This can cause misfiring. If, in addition, an oxygen sensor signal fault ahead of the TWC is stored in memory, first correct this fault and then road test the vehicle.

For TWC read "three way converter".

'course the above if you heed it means I guess you forego buying an expensive MAF and instead buy expensive O2 sensors. Whether you throw an expensive MAF or expensive sensors at the symptoms the key word is expensive in both cases.

In some of these cases one could be better of having the car diagnosed by a shop with a modern Porsche diagnostics computer. Replace a good MAF or good sensors and one has spent over what some computer diagnostics time would have cost and then one is still faced with the symptoms and what to do next.

If you elect to replace the sensors treat the old ones -- in case they prove to be ok -- with care and the new ones likewise.

Use no thread lube!

Do not touch the tips or get anything on them.

O2 sensors are new- I may noit have put that in my summary...I had the original O2 sensors still in the car at over 170K miles. Issue was there pre/post O2 sensor replacement.

MAF disconnected, not removed

I am going with new coils to start, seeing the misfires follow the coils I have ordered them.

When the car starts misfiring the computer tries to compensate. Its inability to compensate can cause lots of other codes. Since the problem followed the coils and it is bank-dependent, the primary problem is almost definitely the coils. I would just replace the 3 bad ones. They're about $50 apiece.

Once you've replaced them, see what codes persist. A lot of misfiring can foul your plugs but I would't worry about that yet.

Agree 100%- I ordered new ones last night. I am going to pull plugs tonight to see what they look like. They only have a few hundred miles on them so not expecting to see any issues there but ya never know. new plugs had no effect on this problem

If that is not the case then yeah, heck yeah, it is the coils.

Or not.

CMA is alive and well.

yes they are following the coils. I went through this very very systematically and last night reviewing my data I came to the conclusion replace the coils.

This is a very confusing issue as there are a lot of variables and codes that point in very different directions. Right now I think the coils are my primary issue...

However, there still may be a MAF issue as well. I need to see if the misfires & O2 sensor issues go away with new coils. I suspect that P0102 might remain

I bought 6 coils, I will replace only the 3 currently in Bank 2 and see if that resolves the mis- fires. I suspect it will.

Thanks everyone for the help... I will report results once I know

Replaced coils on Bank2 and went for a ride- CEL came on quick with P0102 ( Mass Or Volume Air Flow A Circuit Low Input) and pending P1121 (Manufacturer Controlled Fuel And Air Metering) . No misfires so far but hunting at idle once warmed up.
Need to put some more miles on to see if misfires come back. Idle is better. NOT FIXED YET

You need to.

How do I do that?

Done- will see what happens on the ride home- thanks

I got same problem on mine that I just baught. I'm starting to find what's wrong on it.
If you find something don't forget to tell here

under light load [idle] driving conditions.

Fault: MAF faulty.; Harness/connector open; Sensor circuit shorted; Intake air temp sensor.

Do not use the ECM/DME ground terminals when measuring input/output voltages!

When the malfunction is detected the DME enters the fail safe mode and the MIL (CEL) lights up.

Check wiring between MAF sensor and DME for continuity. Engine at operating temperature. Shift lever in neutral or Park. A/C off. No load on engine.

Disconnect MAF sensor harness plug.

Connect special Porsche pin out box 9618 to wiring harness plug. Connect digital ohmeter to pin out box pin 17 and ground.

Measure infinity.

If meter reads infinity check wiring harness for damage.

Tech service note: Check wiring between MAF and DME for short to ground.

Ok-not haveing the special box do you know which pin that would be on the connector. I have schematic- Ground is pin 3 (Black wire) BUT I am not sure what pin 17 in the pin out box is connected to

With one slight twist- first time I have seen misfires on both banks at the same time. Disconnected battery for a few hrs then drove home from work about 25 miles. Close to home CEL came on with these codes.

I think it's BEER ' O ' CLOCK

P0102 Mass Or Volume Air Flow A Circuit Low Input
P0150 Oxygen Sensor Ahead of Catalytic Converter (Cylinders 4 - 6) - Intercore Short Circuit or Limited
P0157 Oxygen Sensor After Catalytic Converter (Cylinders 4 - 6) - Signal Wire Short Circuit to Ground or In -
P1315 Misfire, Cylinder 3, Emission Relevant
P1316 Misfire, Cylinder 4, Emission Relevant
P1317 Misfire, Cylinder 5, Emission Relevant
P1318 Misfire, Cylinder 6, Emission Relevant
P1319 Misfire, Emission Relevant

The P0150 and P0157 all are related to a short circuit of some kind. I do not have the time to type in all the details right now.

Did some wiring get pinched? Mice been in the car? Did you get some bum sensors? Or the wrong ones? Install them wrong? Use anti-seize?

I have already visually checked all the wiring- I see no breaks, evidence of pinching, evidence of mice etc. I double checked that I bought the correct sensors (remember I did all 4- only bank 2 throwing codes for O2 sensor). Not sure how I would install them wrong, connectors only go 1 way. When I replaced these I was already having issues. I decided to replace the O2 sensors as they were the cars original sensors (yes original sensors with 170K miles on them). Because of the idle hunting I was looking for air leak so I removed the exhaust to inspect and replace the O2 sensors so I was able to install easily and torque them in per spec.

I think I will flip the O2 sensors and see if codes follow the sensors or remain as is

Does anyone know what pins should be seeing what voltage etc?

but IIRC the tests do not check for voltages just resistance. The problem is not with the heater or the voltage level per se but that the circuit is shorted or grounded.

If you can wait until Monday when I return to the office I'll type in or copy into a PDF and email to you the test steps.

That would be great !

One thing that is bothering me about the O2 sensors being issue is that P0102 code always present. I get various combinations of O2 sensor errors and misfires... BUT P0102 is always there. I tried something, cleared my codes started car and ran for about 1 minute check codes & only code was pending- P0102. Cleared codes again and ran car for about 5 minutes P0102 was only code pending. Did this again and ran car about 20 miles had Bank 2 O2 sensor codes with misfire codes & the constant P0102.

However- it makes no sense to me that the MAF could only effect 1 bank so... back to the O2 sensors

Quote
Ollie
That would be great !

One thing that is bothering me about the O2 sensors being issue is that P0102 code always present. I get various combinations of O2 sensor errors and misfires... BUT P0102 is always there. I tried something, cleared my codes started car and ran for about 1 minute check codes & only code was pending- P0102. Cleared codes again and ran car for about 5 minutes P0102 was only code pending. Did this again and ran car about 20 miles had Bank 2 O2 sensor codes with misfire codes & the constant P0102.

However- it makes no sense to me that the MAF could only effect 1 bank so... back to the O2 sensors

apparently it can.

Well, it probably affects both banks -- unless there is some goofy intermittent failure mode that gets in phase with one bank but given the firing order it would have to be some real goofy intermittent failure mode.

I know of at least one case -- second hand "know" -- in which misfires on one bank were due to a bad MAF. I say "know" because the symptoms (and maybe the only one) was misfires on one bank. Sorry but I can't recall if there were any other symptoms or error codes.

The usual diagnostics were done with no real cause id'd and then IIRC coils/plugs were done and yet the misfires continued. There it stood until some time later the owner supplied an update: He replaced the MAF.

I do not recall what led to this -- I can guess perhaps desperation but there may have been some science too -- and the owner reported all was well afterwards No more misfires.

So I sat down with a cold beer and a good book (Boxster repair manual)- I think I found the tests you were talking about so I have started some of the testing . Are these the type of tests you were referring to? Still would like to get your write up on the tests. There is potentially more to check HOWEVER...

Part of Test Point 1- Pre/Post cat O2 sensor bank 2 Pin 1 to Grd SB: 12V Is:12.15V- looks good

Part of Test Point 2- Pin 18 to Pin 46 SB: 450 mv, my meter is bouncing need to get a better one, but there is some level of voltage present

Test Pont 16 MAF- Connector pin 2 to Grd SB: 12 Is 12.07- looks good
- Pin 45 to 47 SB: 5V Is: 0V-looks bad
- Pin 17 to 45 SB 1V Is: 0V- looks bad

ALSO- when testing the O2 sensors I found that the Post Cat sensor harness connector is broken. O2 sensor seems to seated in tight & pins appear to be lined up but... Quick question on this- I am going to replace the connector I think I saw some place that I can not solder the wires I need to crimp them due to resistance issues- is this correct????????. I have a connector here as I have an entire engine harness.

My info is the sensor wiring should not be soldered. The solder can bias the voltage reading.