joe hurst

OK, definitely solved now! it was indeed the DME.. so I will again outline symptoms and codes incase anyone else gets the same issue. car would cut out like hitting the rev limiter at 5800rpm, resloved by keying off and back on again. on graphing of TB and accelerator pedal you see an immediate drop in voltage to both, not gradual just a complete loss of voltage to both the pedal, and the throttle body. changing the TB for a new will seem to resolve it as the ecu goes throught the learning process , it will then re-occur. main re-occurring code was P1508, which means torque monitoring fault, I have spoken to several Porsche specialists and the code would be dealt with by Porsche by replacing the DME. we have come to the conclusion that the car was run with a faulty throttle body and the jacking motor was creating voltage spikes which damaged The throttle drivers inside the DME coding. This has been tricky on this particular car as some other faults were masking the issue with ''ghost codes'' which has required those issues to be resolved before being able to diagnose and fix the main issue. also when the cut outs occured there was always more than one code present and the car would on throttle off would run very badly , timing all completely lost. If this does happen to your and is resolved by keying off and back on again i would look at the DME first, maybe borrow one from a forum member if possible. its a difficult one to diagnose as each time a part was replaced the DME would go through an adaptation making you think the problem was resolved ( until it returned each time) if your car is otherwise healthy it would be much easier to track down for sure, and of course hindsight is 20/20! I suppose the upside of this fault is that the car can be driven perfectly below the RPM at which the fault occurs, meaning you have time to sort it, and don't have to get a flatbed and it recovered to a garage. I hope my investigation into it and subsequent solution will help someone else!

you could do a compression test, that would be a good indication of engine health, any HG issues would be obvious on the oil filler cap and or in the coolant. if these come out ok, chances are its ''just'' an immobiliser issue, that can be solved as I said before with an ECU kit from a donor car. when the time to track down the problem becomes an insurmountable obstacle or you can't find anything obvious then its sometimes worth throwing a ''speculative'' part at it. most ECU kits can be sent back with prior arrangement with the vendor. so even if it doesn;t work its diagnostically relevant.

FYI, The electronic throttle body motor can become faulty. This can then cause additional damage to the Engine Control Unit (ECU) throttle body circuit drivers inside the ECU. Guide fault codes logged by engine management system can be P1500/P1523/P1526. If only the ECU is replaced, the same problem can recur, as the real cause is the throttle body motor. This is why it’s advisable to replace the throttle body too. This is on a Vauxhall ECU, but they are exactly the same fly by wire Bosch system, so it's a fair conclusion that the Porsche P1508 code (torque comparison signal implausible) ''could'' be down to bad code in the DME due to the throttle body going bad and causing voltage spikes that dmage either internal ecu components or code. the fact that a new TB temporarily solved it strongly implies this is the case.

only way if it is not working is to change both the DME and the immobiliser from a donor car of the same year, engine code and gearbox code...change the blades from your keys into the Donor fobs. its quite an expense. worth checking it all out on the car first...sometimes the RF transmitter fails so the key transponder can't communicate with the car,the immobiliser itself can be damaged,or you could have wiring issues. start simple, fuses,power to immobiliser, the fuse in it etc.. but first try this.. | Re: boxster remote key not working

Mmm I suspect it will come back, there is really no reason why an engine ''shouldn't like running below 3k'' unless engine diagnostics are adapting in an ''odd way'' there have been further developments this end as well, it came back. so after more reading of codes and live diagnostics and lots of research we have come to the conclusion that at some point in the cars life it has been run for a significant amout of time with a faulty throttle body.. we have found evidence from another fly by wire set up that faulty jacking motor or potentiometers in the TB can cause voltage spikes which damage the throttle drivers in the ECU/DME.. changing the TB will solve the problem temporarily as the car goes throught the adaptation process for the new part, after a period the fault will return...and in fact if you were to change only the ecu and leave the old TB in place then the new DME woud go the same way as the old one. I will be able to confirm this as the following tests/steps are going to be undertaken. 1) swap out the pedal potentiometer ( it tested fine and looks fine under load but who knows ?) this is because the DME uses relative positions of pedal potentiometer and TB to establish desired engine torque/load ( so I'd like to rule it out) 2) re-set all adapted parameters and drive for several cycles with live diagnostics and see what happens. ( I don't think this will resolve it but its a logical step) if/when this fails.. 3) I then have ready to go a New DME/Immobiliser kit and a brand new throttle body, this is my last resort, but if the problem hasn't been resolved with a pedal potentiometer and a Thottle body, Maf, and Lambda's on the current DME then I think it's safe to assume the DME is at fault. wiring has been checked and found to be good, I think our current hypothesis is a good one and having spoken to several ECU specialists they agree it does look very much like a recurring DME fault, add code P1508 and changing the DME is EXACTLY what Porsche would do when seeing this code. I will keep you all updated. should have a resolution this week.

yeah, sound ike you have some air in the system, they are a pig to bleed due to the engine and cooling system layout, lots of pipework compared to a frontmounted engine with the rad directly in front of it,. doubt you have any other issues as the HG on these cars is pretty solid.. best of luck with it.

132k on mine, after some fettling it's running very nicely!

that does sound very like a clutch release bearing to me...but if it doesn't chnage with actuaton of the pedal then it's not that. other than that, try engine flush, fresh oil, Italian tune up with half a tank of premium and a bottle of injector cleaner. thats worked for me before with Alfa TS engines, which admittedly are very diffferent to boxer engines, however i remain of the opinion that cars that are designed to be driven hard benefit from it , and the only cars I have bought that have given me real issues were garage queens that were pootled around in to the supermarket and back. best of luck with it.

I would be looking at variocam solenoids... with most VVT systems issues will appear higher up the rev range as lower down the crank sensor will establish TDC, cam one and crank are key for idle, then higer up cam 2 is for when the vvt engages to the point where the exact injection point for bank 2 cannot be calculated from crank and cam one position, this is the case unless the car is very early and is variocam rather than variocam plus, then you only have ONE cam sensor. my point is the chances of crank, and both cams going bad simultaneously is ''slim'' so something else is affecting timing and the sensors are actually ok. my first guess would be lazy variocam solenoids...crank would just not start or cut out when hot as they go ''open circuit'' and then when cool again all is fine. you ''could'' have one bad cam,sensor ( I would say bank 2 most likely due to issue being higher up the range) and that would be my 2nd guess after confirming variocam solenoids are ok. worth also swapping the fuel pump relay as the noise you say you heard is coming from exactly where the pump is, ( on UK spec cars at least) good luck, live date may well be key on this one.

its confusing, as many P1508 codes are tracked down to the maf as TB, i suggest anyone with this issue unplug the maf and run without to see if the fault still occurs, if it does then there is your answer...It's NOT the maf. things get even more confusing when you are getting multiple potentially related codes, at this point you only have one course of action, live data with post drive analysis and preferably fault replication thrown in, then remove implicated sensors and put them on an oscilloscope... I did all of this and still couldn't definitively know whether the TB, or the DME was at fault...only diagnostic route left was to replace TB with good one. In the end this was how I got my answer but Maf,lambda's, crank and cam, knock sensors, coil packs, HT leads, and supply too all of the above have to be checked first to comletely rule them out..as sometimes thins can be a combination of small problems combining too create a bigger one. I always have one eye on this when diagnosing issues on a car. you can take some guesses, crank wouldn't re-start until cool, rule out. cam sensor fault would affect idle, rule out knock sensors would retard timing and engine would ''ping'' before cut out..rule out if not happening. maf..well anything can happen with those but unplug and replicate fault, if so then rule out. replace lambdas, if they need it, cheap enough and was due on mine anyway. its still a puzzle but not one I wish to engage in again. not on a Porsche anyway!

well.. yes and no. becasue P1508 is potentially one of three things... Maf,DME or TB, now seeing as the Maf and Lambda are related in terms of fueling adjustment I had to go there first...as it does and did feel ''fuelly'' finding bank 2 running a long term fuel trim of 32% confirmed that Lambda was borked that along with a flat line line on the sensor on durametic live data, fuel economy improved when replaced but cut -out not solved...I intially thought fuel supply to bank two was sufficiently differnt from bank one to cause the ecu to step in and cut power... Maf was also ''suspect'' as reading oddly on both durametic and scope, changed and whilst it improved things it still never solved the problem I was hunting down. fuel filter was also the original one! ( inline not in tank as its an early S) and at 130k miles that cannot have been helping.. The TB was reading normally until cut out at which point it gave the same voltage as it would unplugged, but that would also happen if the DME was at fault internally (confirmed with an ECU specialist in the UK) In addition P1508 is porsche speak for ''replace'' DME. you also have an issue that it's difficult to replicate live conditions with the TB off the car, we couldn't see a specific fault even with an oscilloscope ! some oddness yes, but nothing you would bet importan body parts on. My chasing things through was very useful from both a sorting things that needed sorting perspective, and getting to know Porsches, ( I'm an Alfa guy really) and sometimes things don't fail in an expected way. The TB was my penultimate diagnostic/ fault solving step towards replacing the DME, as having ruled out and checked all over possibilities, loom etc, earths, battery cables, plugs,coils,packs etc. I looked up symptoms and codes on forums and got multiple possibilities for all the codes thrown FYI there were Maf and Lambda codes too, and they are often present after the cut outs despite having changed both Lambdas and the maf, that would make sense as the misfires resulting from a ''TB disconnect'' would throw multiple codes. as the car is very early S, it has variocam, not variocam plus and only one cam sensor and two rather than 4 lambdas which did make things easier from a fault chasing perspective. not once did P1508 on any of my multiple searches bring up TB as likely culprit with symptoms like mine, ( hitting a brick wall at 5800-6000 rpm) in fact I found only one and Porsche told the guy to change the DME which he elected not to do, choosing to ''drive the car under 6k'' which is NOT a solution. hopefully this thread will help someone else out as honestly, a month of searching, both online and speaking to Porsche specalists and doing my own investigations has not moved things along any quicker than they might have done by me just doing what was needed in order of most likely culprits. diagnotically speaking given what I found on the history of the car and actually on the car, on the live data, and via the codes would have led anyone in the direction I have gone, only if you have seen exactly the same thing before with a clear resolution would you go TB first. and I could find no such thread.. what seems to be the case with Porsche is less owners actually work on them , meaning a smaller pool of expertise and experience..with Alfa's 90% of owners on the forum self maintain, meaning collective knowledge is vast. I suspect the Ferrari or Maserati owners sites are similar to Porsche in this respect...worth remembering as I plan on a Maserati GT next!

OK, this is now SOLVED. I took the car to a really good Indie, NOT Porsche but with excellent diagnostics, he agreed all of my tests so far had ruled out MAF, O2 sensors, I had changed the fuel filter, also replaced one fo the Lambda's and the MAF anyway. after multiple live data sessions replicating the fault the mechanic in question, ( Lee at on the road car care in Chertsey) had it down to either Throttle body or the DME itself. as there was a P1508 code i thought the worst and assumed DME, however a had a niggling doubt as it ran so well under the RPM where it cut out. I ordered a used TB from Steve Strange at Douglas Valley breakers and fitted it this morning. The car felt happier straight away, idle was a bit smoother but I put this down to battery disconnection , and subsequent resetting f learned parameters. Idle had never been a point of concern but its smoother none the less, the engine felt a little torqier and as as the test drive progressed I started to feel a little more confident that something was indeed different. so onto the acid test. some quiet roads that allowed me to test whether I could get the car above 6k, when resetting the codes in the past it has let me do it, but only once or twice before the dreaded cut out came back. this time I had the car all the way up the rev range 7 or 8 times in a row with no hint of an issue, I am considering it resolved but will of course keep an eye on it over the coming days. a clue was that when the car cut out the data recording was showing a minus voltage on the TB, in fact exactly the same voltage it shows when unplugged. so there was a short in the TB internals somewhere, TB loom was also inspected and confirmed fine. JE17, that where I would start with your issues, by the sound of it it's almost exactly the same as mine. best of luck with it ad report back and let me now what happens..

things have progressed, I have it definitively down to one of two things... sorry to be crptic but I don't want to reveal until i have a definite answer..and there are several routes to said answer... JE17, I will have an answer for you in the next few days...! best Joe

worth a shout as they have a part to play in timing adjustment along with cam and crank sensor, temp sensor , air intake temp sensor etc etc good logic !

Hi Loren, yup, am aware of this, all set up with a local Porsche specialist. will report back when /if it becomes clear what is going on.