pats911 runner

I've been trying multiple things to get rid of my CEL which remains a challenge. I changed the air filters from K&N oil metal filters to regular paper filters. All the literature I've read days the oil-based filters gum up the MAF so took them out. I then cleaned the maf with CRC fluid by spraying liberally. Let dry and reinstalled. The CEL came back on immediately. Here are the codes that I got on my Durametric enthusiast cable:

7910 air mass ahead of throttle valve idle no signal communication

9410 implausible mass air flow ahead of throttle valve. value below lower limit value

I then talked to my shop mechanic and he described needing to reprogramming the ECU and told me to redo exactly what I just did except also unplug the battery for 30 minutes . After doing so and reconnecting the battery cable, I found a PSM initialisation error that cleared itself after I drove the car. For a few minutes. Still one day later thr cel light came back on. I haven't had a chance to check the new codes but I am assuming that the code will be the same as before.

So now I am groping then Web for other ideas to try before I break down and buy a new $500 maf sensor. The cable for the sensor is partially melted Btw - about six inches from the housing. It seems to have touched something hot since it loops down from the housing. I am wondering if the partially melted cable may have something to do with it.

In any case, and ideas on where to check and what could be the issue? Thank you.

Robocop305

I think the melted cable may be the problem.

Petza914

The K&N assembly makes it possible to install the MAF backwards. Try unscrewing it, rotating 180 degrees and re-installing. Clear the ECU again with the battery disconnect then drive the car and report back. The EVOMS and Fabspeed intakes are better than the K&N.

pats911 runner

Not sure I understand. I don't have a K&N assembly -- only the K&N air filters that I have swapped out for paper filters. The MAF sensor is installed correctly (diode side down).

Petza914

Sorry, I misunderstood. Does the car run the same with the MAF disconnected? If so, the MAF is likely bad or maybe a broken connection from the melted wire you mentioned.

malahhaor

Hi all, hopping i can get some pro help from everyone. Didnt want to start new thread so will piggy back on this.
I also am having a implausible mass air flow cel when its cold outside, once the tems got above 50 no more errors.

I looked at some things with my duramatic and got the following...
The V values are with ignition on but engine not running, I know Voltage should not be more than 1.1V when engine is not running but i dont know which one intake air temp sensor or Mass Air. once i turn on the engine i see some misfires? is that normal?

the lady is 06 C4

GodLy

Hello,

Having same issues... Any updates?

I had installed BMC air filters for about 4 months, no issues for that time at all.

p.s replaced MAF, installed OEM ail filters, cleared codes with durametric, but still same codes come over again after ~60s.




new MAF at idle:

GodLy

bump

GodLy

:|

Petza914

Since you mention the issue when it's cold out, the MAF contains the temp sensor - maybe do live values with Durametric for this. Also, the car also captures temp info used in the fuel mapping from the coolant temp sensor - maybe track this with Durametric too. Does the car do the elevated idle (1,200 rpm) when first started cold then drop down to the normal 800 rpm or does it first start at 800 rpm?

Did you try driving the car with the MAF completely unplugged. Does it drive the same or different. If the air temp sensor works and there is a difference when driving with the MAF unplugged, you may want to smoke test the intake to try and find a vacuum leak, which could give you these errors since the o2 sensors are seeing an imbalance between the metered air on and the mixture out. Could also be a bad O2 sensor.

syzygy333

regardless, I would open melted section and fix that issue straight away.
possible to borrow same from any source to replace and possibly diagnose?
also find heat source and correct this!

GodLy

Thanks for replay!
Well on car start i have much white smoke, but at dealer they told me this is normal.. anyway for me some how it wont look normal.. Smoke smells like water, so it can be condencate but also you can smell little of fuel..On the cold start RPM's goes up and after some time goes down to 800 so as i know this is normal.
Anyway i will drop car to the dealer.. And lets see what they find..

Petza914

Unless it's really cold out (30 F or below), you won't see white smoke on an initial start, and in that case, it's actually not smoke, but steam (condensate as you state). Even if it's cold out, it takes a couple seconds before the exhaust exiting the tailpipes will show that condensate. If yours is doing it immediately, and it smells like coolant, you may have another issue, possibly something related to the heads / valves, or unlikely but even worse, a cracked cylinder that's allowing coolant into the combustion chamber from the coolant flow passages that surround them.

Let's hope it's something more minor, but let us know what they find.

GodLy

Well yeah it starts smoke after few seconds and smokes around 1-2 mins then it goes away.. not matter there is winter or summer.
Talking about smell, it do not smells like a coolant it smells more like a boiled water/steam but as i told before there is some "notes" of fuel.

My car has now 140k milage (kms) and at 133k i had:
10100 crankcase / 1822 grooves signs of seizing
24400 injector valve / 1611 no function

and at 138k:

26730 catalist converter / 1611 no function

So as i understand porsche changed converters, injectors and crankcase..

Macster

Upon cold start, and it doesn't have to be near 30F for this to occur in my experience, after a moment the exhaust will emit water vapor. There might be a bit of smoke mixed with this for as we all know these engines will emit a bit of oil smoke upon cold start once in a while.

Smoke hangs together even if it is carried away by a light breeze. Water vapor dissipates even in still air.

Even with a healthy/properly runnng engine, upon a cold start the exhaust will certainly contain "notes" of fuel. Everything is cold and this includes the converters. The DME supplies extra fuel which along with the air provided by the secondary air injection system is intended to burn in the converters to warm them up quicker. There will be a time after cold start that some unburned fuel will make it through the converter and this is what you smell.

As an aside, concurrently with the cold engine RPMs dropping to near normal hot idle level the DME switches from open loop mode to closed loop mode. It can do this because the sensors are working properly and the ones after the converters are signaling the converters are working.

Anyhow, with me handicapped by not being at the car all I can offer is unless the cloud is indeed smoke, exceptionally heavy, and white -- these would suggest an overly rich mixture at start up perhaps due to leaking injector(s) -- what you are seeing is probably normal cold start smoke/vapor.

As for the codes "7910" and "9410" I have nothing in my references.

All I have to go on then is the description that accompanies the error codes in the pics you posted.

7910: Air mass ahead of throttle valve, idle. No communication.

9410: Implausible mass air flow ahead of throttle valve. Value below lower limit value.

Not much to go on -- a tech would have his training and possibly a list of diagnostic steps to follow when encountering the above error codes but I have, we have nothing of the sort available to us -- but there's a common thread. "No communication." "Value below lower limit valve."

You have installed a new MAF. I trust it is one in which you have a high confidence that it is the right one and how to put this? Not some super cheap/questionable quality MAF?

I'm probably stating the obvious but no communication and a value below lower limit valve suggests a wiring/connection problem. (This assumes the new MAF is not defective and just "dying" a short time after engine start.)

I don't know the history of the car. I don't know what might have been done to the car -- servicing, repairs, modifications; prior to the error codes appearing.

With suspected wiring/connection problems, a couple of things come to mind. One is apparently the car received some rather extensive attention a while back. One must always then be concerned about a connection being marginal that in some way say has allowed moisture to enter the connection and corrode the connector pins and affect the signal. Or a portion of the wiring harness got damaged/pinched.

There is the concern about moisture getting into the car. In this case not necessarily the cabin but where the DME is located. Or the fuse box. Or into a relay box.

And of course if the car has sat any length of time infrequently or not used at all there is the possiblity of mice having been at the car, its wiring.