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Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Wed Jun 07, 2017 8:19 pm    Post subject: Reply with quote

An air leak wouldn,t give the symptoms you have got .. mine runs pretty much ok but logs a fault for air leak between maf and throttle , im of the opinion the car then adapts to this so no real driveing symptoms .

My hope is a maf has failed but in range so no code and its reacting to the maf reading .. soon find out when you replace them .. unplugging just makes the dme drop to defaults so it masks any fault , still strange though how it happened .

Anyways .. if it doesnt fix it then i have a challenge on my hands .. i do love a good challenge Very Happy
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Scubadiver
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Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Wed Jun 07, 2017 9:53 pm    Post subject: Reply with quote

Haha, well I'm very happy you love a challenge!

A small amount of progress was made today, but unfortunately the company I ordered the two MAFs from only sent one and it was a pattern part rather than genuine.

I fitted the one that did arrive to the offside as that was the one I tested and didn't seem to work. It's not a great fit though, the diameter at the air filter side is too small so doesn't seal. I did however fit it, reconnect everything and clear the codes and started the car....... it works!

I decided a test run was in order, so I drove to the nearest petrol station 9 miles away and everything was fine. Filled up with some of the 97 ron good stuff and headed back and (of course) put my foot down. Straight away back came the PSM warning Sad Still drives, but in that 90% OK mode.

Pulled over and scanned it and got P2281 and 1314. Cleared those and set off again gently but the PSM warning immediately came back (same codes when scanned). When I got home I took the new MAF off and refitted it with RTV so it will now seal and left it to dry. Back on it again tomorrow!
 
  
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Scubadiver
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Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Thu Jun 08, 2017 5:44 pm    Post subject: Reply with quote

Thought everything was fine today, went out for a 20 mile test drive this morning and all was well. Took the car out to actually use it this afternoon and the PSM warning came back (under quite gentle acceleration this time!) with those same fault codes.
Each time they're cleared they come back and Googling their meaning it looks like I too may be chasing an air leak. Or maybe in need of a MAP sensor?
 
  
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Scubadiver
Newbie


Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Thu Jun 08, 2017 5:57 pm    Post subject: Reply with quote

Interestingly, the Torque app brings up two different codes. P2187 and P2189.....
 
  
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Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Thu Jun 08, 2017 7:47 pm    Post subject: Reply with quote

The fault codes are ..

Air leak between MAF and throttle body
Misfire cyl 2
Bank 1 Too lean at idle
Bank 2 too lean at idle.

You didnt have these faults before you fitted the new MAF sensor i belive and they all relate to an air leak or an incorrect reading from a MAF sensor.

Cayenne MAFS are air flow tested with the tube it comes in , if you are just replaceing the MAF without the tube then its not correct .

The Porsche ones are something like £350 each .

It doesnt take much of a difference in MAF signal to cause running faults.

Your car has gone from not running unless MAF disconnected to running ok .. ish but with different faults with this new MAF .. so logically its the MAF thats not very good .

MAP sensor is always a possibility .. all i can say as a basic check is there should be approx 1.8 volts at idle but i use a tester to confirm that reading .
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Scubadiver
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Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Fri Jun 09, 2017 11:27 am    Post subject: Reply with quote

Thanks Demort, I must admit I did feel a little dirty inside fitting an obvious pattern part (that didn't fit well) Laughing

I thought I'd ordered a pair of Bosch MAFs along with the housing/tube (0280218071) What I actually got was one pattern equivalent sensor/tube and the following day I received a genuine Bosch sensor but without tube (F 00C 2G2 047).......

Although I ordered the 0280218071 as I thought it would be nice to have complete, clean units I wasn't aware that just changing the sensor on it's own wouldn't be right, so looks like both items I have here are fairly useless!

I'll put that down to experience and have this morning ordered two complete genuine Bosch units from a different supplier. Although these were not £350 each from Porsche, I assume that the OEM supplied part is a re-boxed Bosch part as was fitted to the vehicle?

I feel like it's very nearly there anyway and in the brief time when the car has functioned correctly I absolutely love driving it. It'll be nice to get this resolved so I can move on to the other issues Laughing
 
  
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Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Fri Jun 09, 2017 7:49 pm    Post subject: Reply with quote

Pattern parts can be either cheap and nasty or genuine reboxed items , i leave that to the parts guy to sort out but as a garage we tend to use OEM or porsche parts mainly .

I had a look at an 05 turbo that is fine today just to have a look at some of the figures .. when hot after a good run the mafs read 1.19 volts and 1.17 .. i had to rev it to 1k rpm to get the same readings i do on my faulty one .

There was also an imbalence on this one but through the rev range they were pretty close to each other

So take the above as a guide to the correct values for mafs .

If the mafs are over reading then the car compairs these to the pressure sensor and flags up an air leak code so i know the mafs are faulty on mine .. that and one is covered in oil lol .


Ive already said it wants x2 mafs on mine but as there is a fault with a turbo as well then the customer when quoted for the work is not continuing with the repair .. cant say i blame him .. repair is more than the cars value sigh .

I have checked it and the maf and tube are one unit .. Porsche say not to replace just the maf as its air flow tested as one unit .

Btw .. when its all good and you give it some stick and enjoy the power .. keep an eye on your fuel usuage .. might use a little more than you expect Wink

Mine ran out today but came in with over a quarter of a tank .. opps .
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Scubadiver
Newbie


Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Sat Jun 10, 2017 3:37 pm    Post subject: Reply with quote

Haha, easily done I'm sure! I'd think single digit figures would be achievable given a little effort... Laughing

Continuing bad luck with parts for mine, I ordered two Bosch MAFs yesterday morning and paid extra to have them sent Royal Mail 1st class to get here today. Postman has been and gone, turns out they sent them FedEX next WORKING day instead so won't get them until Monday at the earliest, although the tracking number they've supplied isn't even recognised on the FedEx system so who knows....

Still, gives me time to look at some other bits, but I'll start new threads on those.

Turbo writes the car off? Is it true the engine needs to come out to fit then?
 
  
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Scubadiver
Newbie


Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Sat Jun 10, 2017 7:55 pm    Post subject: Reply with quote

So, thanks for taking the time to check the voltages Demort, I've just checked mine again with the new MAF that I fitted the other day.
Of the four wires connected to it, I have a green that is 12v negative, a thick black that it 12v positive, a thin black with yellow trace that is 5v positive and a thin black that is the variable positive. On the old non-functional MAF, this voltage would remain a little over 1v regardless of engine revs. With the new one at 3000rpm the voltage increases to a little over 2v.

More specifically:

With the engine off, both read 1v. At idle the o/s (new) reads 1.17v while the n/s (old) reads 1.23v.

At 2500 rpm both read 1.75v give or take 0.02v

At 3500 rpm o/s reads 2.23v while the n/s is 2.12v.

So, there is an imbalance there currently (and the new o/s MAF has a greater range, starting lower at idle but ending up higher at 3500 rpm than the n/s), it will be interesting to see how the readings are when both sides have been replaced for the new ones arriving Monday (hopefully!).
 
  
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Scubadiver
Newbie


Joined: 03 Jun 2017
Posts: 29
Location: Norfolk, UK


PostPosted: Tue Jun 13, 2017 9:00 am    Post subject: Reply with quote

I'm pleased to say I think I can now bring this to a positive conclusion Very Happy

I fitted the two new Bosch MAFs and also for good measure a new Bosch MAP and all is well. I've now taken it for a couple of thorough drives and everything appears to function as it should. Very happy!

Once again, thanks for all the contributions while I'm getting to know this vehicle, and especially Demort - I certainly owe you a drink! Laughing
 
  
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Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3247
Location: Sussex


PostPosted: Tue Jun 13, 2017 7:47 pm    Post subject: Reply with quote

Excellent .. i love a happy ending .

It does go to show though that cheap parts can actually cause other issues or fault codes .

Helped me as well , although i couldn,t continue with mine im 99% sure now it was the Maf sensors that i flagged up at the biginning of my job .. bit of a waist of time going down the air leak fault path .. but no worrys , always good to learn something new .

Turbo .. ive never tryed to change one in situe but from looking i would say its an engine out job and that is a rather big job .. engine , box , subframe and front struts/brakes all come out as one unit .

big frame to support it on and when you undo the last bolt the whole car rocks on the ramp as the weight is released ....

Only time in 35 years ive ever nearly had to have a change of underwear was when that happened to me !!!

Btw some Cayennes are worth money and some are not Very Happy
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