Very rich mixture, out of ideas..

[doubleb]

Hi everyone,

After DME reprogramming, new MAF, 4 new oxygen sensors, new spark plugs, the Cell is back (after 5000 miles) :(

I get the codes:

- P1125

- P0130

- P0156

- P1276

I took out all 4 oxygen sensors just to check (last time the oxygen sensor ahead of the cat was clogged completely), and yes don't know why, but same issue this time. But only on one side ahead of cat.

Cleaned the oxygen sensors, new spark plugs (just in case), reset the DME and it ran fine for 20 miles. Now the car idles poorly and smells like gas again. It is so rich that the exhaust is causing the extire backend of the car to turn black with deposits.

What can it be??? I cannot detect any vacuum leaks, and everything else has been replaced. :renntech:

Sebastian

Edited May 26, 2007 by doubleb

[Loren]

Model year please?

[doubleb]

Hi Loren,

My car is a Boxster S - 2001.

Thanks.

[doubleb]

Model year please?

Perhaps allso good to know:

On the left side (drivers side) the oxygen sensor ahead of the cat was clogged, but the spark pugs were very clean.

On the right side, the oxygen sensors were ok, but the spark plugs were black with deposits.

[Loren]

Where do you live and what type of fuel are you using?

[Rodger]

Also, if the plugs look OK but the O2 sensor is completely fouled, what type of plugs are you using and what heat range are they? It's best if you can provide the actual numbers off of the plugs.

Was the DME reflashed with an upgraded tune or simply a new version of the factory tune you're supposed to have? Any mods to the engine?

I get the codes:

- P1125 - O2 sensor Cyl 4-6 lean threshold

- P0130 - O2 sensor Cyl 1-3 intercore shorted or limited

- P0156 - O2 sensor Cyl 4-6 intercore short circuit

- P1276 - O2 sensor Cyl 4-6 aging, below lower limit.

If you've got a Durametric, I'd recommend logging some actual values after resetting the DME. I'd specifically look at the O2 sensors, MAF, and coolant temp sensor if they're all available simultaneously. You also may want to try disconnecting the MAF to see if it affects the richness.

Would you please also provide a rundown of the parts you've replaced, and whether or not they were new from a dealer or from a parts store chain.

Edited May 26, 2007 by Rodger

[doubleb]

My DME was upgrated by my Porsche dealer. Allso they put in the later style MAF with partno.: 986-606-125-01

The shop put in some new Beru spark plugs with partno.: 14FGR-6KQU Z129 / R6545 some 5k miles ago and the car was running great. I just replaced all plugs yesterday (same type) to be sure the plugs weren't the issue.

Seems Cyl 4-6 are out of range, perhaps due to the clogged oxygen sensor? I unclogged it, but could be broken as well? All 4 oxygen sensors are only 3 months old.

Does anyone knwo what these codes actually mean?

- P0130 - O2 sensor Cyl 1-3 intercore shorted or limited

- P0156 - O2 sensor Cyl 4-6 intercore short circuit

Parts that were replaced (by dealer):

-MAF

-Plugs

-AOS

-Oxygen sensors

-DME software

Can I test to see if the clogged oxygen sensor is broken by exchanging it post- or pre cat or to the other side? Or disconnect en see what happens?

Thanks.

Edited May 27, 2007 by doubleb

[doubleb]

Well just disconnected the MAF en resetted the DME. Car runs slightly better now, but still the gassy smell. If my MAF broken or could it still be the oxygen sensor?

Edited May 27, 2007 by doubleb

[FrayAdjacent986]

Maybe the later style MAF doesn't work properly? Maybe the dealer didn't 'upgrade' your DME firmware, maybe they flashed the old parameters to it, and it doesn't work well with the signal from the MAF.

I'd try to obtain an older style MAF and see if that resolves it.

[doubleb]

Well after reprogramming the DME and using the later style MAF the car has ran great for months, and I use it on a daily basis so that's not is. Something has broken but I cannot figure out what..

[FrayAdjacent986]

Well after reprogramming the DME and using the later style MAF the car has ran great for months, and I use it on a daily basis so that's not is. Something has broken but I cannot figure out what..

Well, if it runs fine when you disconnect the MAF.... I'd think it has SOMETHING to do with the MAF.

[doubleb]

Maybe. But still got that very gassy smell. Wouldn't want to keep a lighter anywhere near the back of the car... :(

[FrayAdjacent986]

I would suspect the default fuel map used when the MAF is disconnected would be on the rich side. It's going to want to prevent burning up cylinders by going too lean.

[Rodger]

What did you use to clean the O2 sensors? Also, have you replaced any of the O2 sensors? I noticed you didn't list them....

If you've got a voltmeter or a Durametric you can look at the O2 sensor's outputs. You might want to see if your O2 sensors are developing any voltage at all. If not, replace them.

[doubleb]

Hi Rodger,

Yes I replaced all 4 O2 sensors 3 months ago. After checking them 3 days ago, there was just one that was slightly clogged. I unclogged it with a small srewdriver (not toughing the inside "nose" ofcourse).

I have now driven 200 miles with the MAF disconnected and the car runs fine. Missing a few horses for sure, but no more rich exhaust fumes and the idle is fine too. Don't get a CEL light though. Isn't that stange?

Can this only mean that my MAF has gone south again??? Or can there be some other things wrong with it as well?

Edited May 28, 2007 by doubleb

[doubleb]

Hi Loren,

Do you have any idea? :thumbup:

Just the MAF at fault here?

Thanks!

Regards,

Sebastian

[Loren]

Well, OBD II is different for Europe than the US - in the US you will get a CEL with the MAF disconnected (in a day or so).

If the car runs better with the MAF disconnected then that is one of the problems. I think you need to replace it and see if any other codes come up.

[doubleb]

Agree! Will try that tomorrow. Thanks for your help (**** it's early is the US ;-)

[doubleb]

Well problem solved :thumbup:

Turned out to be just the O2 sensor ahead of cat on Bank 1 (causing the P0130 CEL). MAF was fine.

Shows to see that if you disconnect your MAF after strange symtoms it doesn't automaticly mean your MAF is bad.

Now enjoy driving it again. ;-)

Thanks guys!

Edited May 30, 2007 by doubleb

[FrayAdjacent986]

You're right, it doesn't indicate the MAF is bad... because the MAF AND the O2 sensors dictate the mixture...

I guess removing the MAF also tells the DME to ignore the O2 sensor's input as well.

[doubleb]

Well the codes are back again:

P1125

P1128

P1126

P0130

(Boxster S - 2001)

Car is running crappy and smelling like gas.. Any more ideas?

FYI car started having problems after dealer changed the clutch & flywheel (having to partially take off the exhaust?). I noticed some mess with sealing material between the two exhaust halves. Could that have anything to do with it?

Edited June 2, 2007 by doubleb

[doubleb]

Noticed it mostly smells like gas comming from the right tip of the exhaust (passenger side). Checked bellows but not cracks or leaks. Neither in the exhaust system (as far as I can see or feel). Can the O2 sensor after cat be at fault? Can get that one to get loose..

Loren do you have any clue as to what's going on?

Thanks!

Edited June 2, 2007 by doubleb

[Loren]

P1125 Oxygen Sensing Adaptation, Upper Load Range, Bank 1 – Above Limit

This says that the DME can not make the mixture enough rich (under load) - it is sensing a lean condition that it can not compensate for.

P1128 Oxygen Sensing Adaptation, Idle Range, Bank 1 – Above Limit

This says that the DME can not make the mixture enough rich (at idle) - it is sensing a lean condition that it can not compensate for.

P1126 Oxygen Sensing Adaptation, Lower Load Range, Bank 1 – Above Limit

This says that the DME can not make the mixture enough rich (under load) - it is sensing a lean condition that it can not compensate for.

P0130 Oxygen Sensor Ahead of TWC, Bank 1 – Signal Implausible

This says the signal at this O2 sensor is either shorted or at battery voltage.

Right now the codes say you have trouble only on bank one. Has the sensor ahead of the cat been checked/replaced?

What else has been replaced at this point?

Please tell me - at this point what has been changed?

[doubleb]

Hi Loren,

The O2 sensor before cat on bank 1 has been replaced, but still the same P0130 code.

Can the O2 sensort after cat be at fault? I cannot get it loose to inspect it..

Allso how can P1125 & P1126 exist at the same time?

Thanks!

[Loren]

If the O2 sensor has been replaced and you still get the "signal implausible" fault then either the wiring is bad or the DME is bad.

Why would you suspect the O2 sensor after the cat? It has no faults.

The sensor (readings) before the cats are used to compare with the sensor after the cat (readings) and other inputs from the temperature and air flow (MAF) for the DME to adjust the mixture. So, if you were not getting the P0130 fault then I would say the MAF is faulty - but since the O2 sensor on that bank says it is shorted (either to ground or +12 volts) you can not trust the other faults because it can not get proper readings.

IMHO Step 1 is still to correct the O2 sensor problem on bank 1 before the cat.