MAF sensor hot film values, correct?

I got a P1109: porsche code 549 input variables charge measurement - checked the throttle body: clean and all ok - checked the MAF sensor hot film voltage with durametric ignition on engine off : 1.03V engine idle: somewhere 1.32-1.37V From my memory those values seem to be ok, is that correct? (cannot find the reference) Anybody can give me a tip what else I should check? UPDATE found a troubleshooting for the P1109 code Seems like the MAF sensor is still within spec. Will try to check for some vaccuum leaks on the intake side.

Nothing in the possible fault causes mentions a vacuum or intake leak. But of course check if you want. What was the freeze frame data? That's a snap shot of some engine telemetry at the time of the error code which triggered the CEL. I've dealt with a number of CEL events and error codes over the years and often the error condition is transitory. The condition worsens until it is bad enough to trigger a CEL but for some reason the condition improves. Almost certainly -- at least in my experience -- an engine off followed by a restart -- will have the error condition gone. What I've done in a few cases is had an OBD2 code reader/data viewer connected to the car's OBD2 porrt and in real time monitored the data signals of interest. In one case it was the O2 sensors. It would take around 30 minutes of driving but I finally got to the point I could anticipate when the problem was about to surface and in one case I was watching the tool's display when the sensor went bad. The CEL came on about that time and as expected the sensor seemed to recover. Its readings were still not all good compared ot the other side but it did improve. What can you do? First any pending error codes? If there are any those would be of interest. In the meantime, something easy is do an E-Gas calibration. This can also possibly eliminate the throttle body (the "adjusting unit") from the posssible causes. Clear the error codes. Then peform the E-Gas calibration. The steps should be covered in the owners manual. For my cars: Start with the ignition key off and your foot off the gas pedal. Turn the ignition key to the on position. Leave in this position at least 60 seconds. Turn the key off and leave off for at least 10 seconds. The next time the engine is started the calibration is complete. If a bad E-Gas is suspected and it should be given the list of possible causes above, then check for any error codes again. If none then road test the car. If the error comes back then step 2 would be to clean the throttle body. Haven't checked but only once or twice but the first time I checked I found the throttle body of my 2002 Boxster quite "dirty" mostly with oil but this was due to a failing AOS. I checked the TB prompted by the engine's erractic idle and other symptoms. The hose from the AOS connected to the intake manifold directly behind/after the TB and the failing AOS was passing so much oil vapor that this fouled the throttle body and its butterfly valve with oil vapor. It was so bad there was a drop of oil hanging from the throttle body butterfly valve. A cleaning helped, for a while, but the real problem was the failing AOS. If you clean the TB handle it with care. You drop it you buy a new one. Be sure when you reinstall it you do so with no leaks. Use a suitable cleaner. Avoid moving the throttle body butterfly valve. Just spray the unit down let it drip dry then reinstall. Before you reinstall check the area downstream of the throttle body. If very oily -- if the throttle body oily -- this can be a sign of a bad AOS. The techs tells me even with a healthy AOS it is not unusual to find some evidence of oil on the intake walls downstream of where the AOS hose connects but there should not be a lot of oil.

Thanks for the input. Alsways very detailed your replies No CEL light. I just encountered the code when reading intermediately. The things you refer to were exactly those I already performed the E-gas calibration. No succes, code comes back. No CEL Then verified how clean the intake path is. This would haven been very unlikely as I just reinstalled 5000 miles ago ago the IPD competition plenum with the larger 82mm TB which was spotlessly clean. Furthermore the tubing of my AOS is rerouted so that it cannot dump its oily content straight into the intake. This is mainly a preventive measure in case the AOS fails, to prevent the larger amounts of oil that could end up in the intake and cause a hydrolock, So a dirty TB is also not in play. Faulty TB I consider as unlikely as it is not that old. How could I find out? Maybe I used the wrong terminolgy when mentioning I was going to look for a vaccuum leak. Lookign for false air? Any way I found a possible cause. When installing the competition plenum it comes with a bigger silicon hose to fit the larger TB. As my car used to be a triptronic I still have this vent line which is connected to the OEM air intake hose (see photo below; not my car) BTW does anybody knows where this vent line goes to? EDIT: I found the function of this tube/hose/line; see this topic I modified the silicon hose that came with the IPD plenum and glued the elbow of a OEM air intake onto it to connect this vent line (see photo below of my car). Knowing that it could be a weak spot in the hot engine bay. I was right the elbow came loose. So false air could get past the hole there into the intake.

When constructing my first response I was unaware the intake had been modified. The general rule is if a problem appears out of the blue (so to speak) the last thing touched is the first thing suspected. In this case then a double check of the after market intake modification installation is certainly called for. Anything that allows in unmetered air has to be dealt with. There is the also the concern that even if the air is metered, that is it comes in upstream of the MAF, the introduction of this air upsets the laminar air flow that the MAF requires. This can result in erratic MAF behavior. The behavior can have one believing the MAF is bad when the air flow is the culprit.

As you can see the elbow that was fitted is located downstream of the MAF sensor. Located at the same position as the OEM throttle body bypass hose. I ran this setup also some months ago. Without any error codes. Maybe the throttle body butterfly got touched unnoticed during (dis)assembly or handeling and storage. Will go down step by step all the possibilities. Have ordered a new silicone hose. Will cap the little hose that goes from the OEM air intake. To the intake manifold. As it is there for smoother operation of the car with a torque converter running. That is not anymore the case. Thx for the input!

Update: - fixed the leak in the rubbber intake hose - decided to replace the MAF sensor as the read-out of the hot-film value was 1.06V. New one is 1.0V Besides that did some normal maintenance, new oil and filter; magnetic drain plug was clean. Nothing to see in the oil filter. Installed the Bilt washable filter. New spark-plugs. All set. Installed the new cross over 200cell cats, had to put new O2 sensors as the old ones are stuck and could not taken out without damaging the thread. Engine runs super smooth, car pulls strong, P1109 gone, Nice exhaust tone of the 200cell cats in combination with the Cargraphic mufflers!

So after driving some time I got the P1109 code back. I was thinking if it might be related to the change over valve which operates the varioram and the resonance flap which forms part of the intake. Do I say nonsens now? Did not have the time to verify. How could I check if it is working properly?I have a durametric.