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981 S faults not picked up by diagnostics

ar3910

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Joined
25 Feb 2019
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4
Hello,

I have a 981 Boxster S with a PSE, always been serviced on time and no expense spared. Always warmed up before driving hard. It is on 57000 miles so slightly higher than most out there, but not massive.

I noticed around 6 months ago that the exhaust was no longer popping like it used to on overruns. I took it to Porsche who said that they couldn't fault it as the valves were opening correctly, and there were no error codes being thrown up on the diagnostics machine. The engineer said possibly a spark plug could be to blame if it persists, as the artificial pops created by the ECU wear down the spark plugs in other cars, but unlikely as they were changed with the service 2 years prior and should last many miles. I thought that I must be imagining it, so I didn't think much more of it.

Another strange thing which happened was that around 2 weeks later, I heard a loud pop, followed by a hissing, then loud squeals until I turned the car off. I then turned the car back on after waiting a little while, and there were no more squeals, no warning lights or faults on the dashboard. I called Porsche Assist who said that if there were no warnings to carry on my journey, so I did and have heard nothing since, so thought maybe something small was sucked into the side intake and found its way out.

The other day, after driving hard for about 10 minutes, I noticed suddenly that the car didn't seem to sound as loud going through the rev range - it used to have a much higher pitched scream as you went past 4-5k revs, whereas now it sounds very muted and deep, like a turbo for example. It also doesn't feel as quick as it used to so has lost some performance. I am too scared to push it any further in case it damages anything further, but again, no warning lights on the dashboard, and no error codes when I took it to Porschacare a couple of weeks ago for a quick once over.

I'm convinced there is something wrong with the car now, but not sure why there aren't any error codes showing. I have read about VVT solenoids possibly being an issue with higher mileage cars, and that they sometimes don't show up with any warning lights when fail, but not sure if this sounds like that as I am not very mechanical. My other options are spark plugs, coil packs, a vacuum hose leak, or vacuum valves/pump failure, but I have been told all of these should throw up a warning light or error code on the diagnostics machine. If anyone has any idea what it sounds like, I would be hugely grateful! I also have a Porsche warranty - does anyone know if any of these are covered under that? And how to go about pushing for them to find an answer if they keep saying there are no faults on the diagnostic machine?

Thank you!
 
First off .. were in the country are you ?

i doubt you are down South but i always ask .

My way of thinking .. if you have owned the car for a while .. 6 monthes or more and something seems to have altered then im of the opinion it has ..

you know the car and know if something is different so even if no fault code then there is something going on .

Now then .. 981 and the fault code system is pretty good .. most things are covered ..

Whats not covered is a sensor failing inside of limits .. to a degree anyways ..

High lift solinoid for the tappets , it can in theory not fully work and you wont get a fault code .. fuel pressure is not monitored on these cars .

The exhaust .. PSE .. that wont give a running fault but will sound different .

I would be looking at the actual values for the different sensors from cold to operateing temp .

i would look at the fuel trim values .. is there a range .. say idle were the mixture is wrong ... called Rkat btw .

In essence .. no fault codes doesnt mean there isnt a problem .. it just means its going to be a bitch to find .

there is nothing i can say thats actually wrong .. bit of a needle in a haystack is that question but there is other things to check other than just looking for a fault code .

The downside of OPC im afraid .. no code and no fault ...
 
Ah well I'm in Hertfordshire so fairly south but not fully south of England.

Thank you for your post. It seems like there is something going on then, but it will take a lot of investigation to find!


Your suggestions are quite technical and you obviously know these cars in depth, hats off to you. If I asked an average Porsche Indy and gave him these suggestions should he be able to understand what I mean and investigate these things quite easily?

Thanks
 
ragpicker your making me blush young man !

Im an average indy Mechanic these days .. 10 years of OPC was kinda enough for me with the constant chaseing you for hours sold , expecting you to find more brake pipe faults as one of the other guys found more than me etc etc .

I digress ..

Ok so you are not close to me so i wont get to look at it ..

Ill just reiterate .. if you have had the car for a while and something is different then it probably is .. but for a mechanic it gets kinda difficult ..

Most guys work off of a fault code and when there isnt one they either assume the car is fine or the customer has just bought the car and doesnt know it .


i assumed all Indys were the same untill i came here and started posting .. i then learnt that they are not .. big shock for me i can tell you !

So the problem as i assume you dont have a normal garage you use is in finding one .

Then its about how they approach the problem ..

No fault code and you are looking for any item that isnt covered by a code or something that has " stuck " .. something that gives a reading the car accepts but isnt correct for the situation .. a slow or under reading sensor basically .

its all about looking at the actual values and trying to pick up on something thats not quite right .. there are a lot of sensors and things to look at on these though im afraid .

i know i would struggle from the description .. but i would be looking for a fault and not looking to say .. customer or its ok .. thats the edge .. belive there is a fault .. look for it .


I have a Hunch but its only that .. high pressure fuel pump .. a normal fail will give you fault codes but im wondering ..

i would connect a tester and graph the nominal and actual values .. what the car wants and what the car gets fuel pressure wise ..

I would have a mechanic drive the car whilst i graphed the data .. i would say accerlerate now and watch the figures .. then deceletate ..

this would be a long road test and i would print out the results and compair what the car wants and gets basically ..

As i said its a hunch but possibly the start of a high pressure pump failure .

Dont get me wrong there are mnay things it could be so dont go throwing a pump at it .. but its a hunch .
 
Thanks very much for your help and advice. I have booked it into an independent garage so will give them this to look at so it can offer a bit of direction if they struggle to find a problem. Will give you a shout if I'm ever down south! Thanks!
 
It is entirely possible its something on the PSE .. but my feeling is its been looked at .. its a simple system so i kinda ruled it out ..

Either way i recon an Indy will get to the bottom of this .. i just hate it that all the interesting jobs are with people so far away from me ..

Its typical on this forum im afraid .. none of you lot live anywere near me .. sigh .
 

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