My mechanic is stumped. Need help from Rennlisters Please.........

2003 c2 6mt w/ 41k on the clock. First the car would die at idle sitting at a light . After a minute it would start back up and go with no issues. This happened once a day for three days. On the fourth day the RPM's at idle would start to fluctuate between 700 and 1300. This would go on for about a minute and then power would start to cut in and out while in gear at cruising speed and then die. Check engine light would come on at this point. After a minute would start back up. This would always happen about 10 minutes after initial start or right about when it got to operating temp. My mechanic which has over 20 years experience with P-cars originally thought it was the crank sensor. Replaced it and reset the codes. Picked up the car and went for a fairly spirited drive that evening redlining first three gears a few times. Car felt great with no problems whatsoever. On the drive to work the next day same thing happened again! Rough idle, engine cuts out, check engine light comes on. Went back to shop and they're trying to figure it out. The hourly rate for diagnosis is killing me!!!!!!! Has this happened to anyone before. Any suggestions would be greatly appreciated......

Post the codes. check fuel delivery....pump, hoses

Idle control valve?

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MAF?

had similar - not exact problem - long story short it was this rubber that was slightly off - had been sucked in by intake (see photo where I'm pointing w screw driver) - and thus it was getting too much air, giving readings about vario cam timing being off (very hard to really happen) and causing stall at low speed/idle but fine aboe 2k rpm. hope it helps. can reach it without engine drop altho that's the only way we found it. ie the part of the intake behind the plenum.

Good post above. Yuo might need to check the wire continuity to the crank sensor? Only suggesting because the car ran great for a time then symptoms reaccured. Best of luck, Paul

also check your fuel, I'd say run the tank off , add some additive like techron and fill her up at a reputable gas station that see decent amount of traffic (gas not sitting). I had some idle problem once when I made a bad fillup at a not so great gas station.

So any news mic?

Just a suggestion here but as you have already changed the CPS and you are still having the same problem, have you checked for any horizontal play in the crankshaft? <just a thought>

Disconnect maf. And run like that for a day. Will rule that out at least. Leak in vacuum hose somewhere would also be possible cause......

********Update****** Timing was consistently off with cam and cranks sensor error codes. Conensus is the IMS is about gone. Hopefully no engine damage is done but we obviously won't know until he opens it up. Luckily I bought a warranty for the engine when I got the car a year ago. New bearing from LN has been ordered. I will have to pay for the difference in price and shop supplies which is not that much. Fingers crossed on the condition of the motor.

Best of luck to you! I am not a fan of aftermarket warranties, but it seems like this time it really is going to pay off.

It sounds alot like what I said above. You'll be ok. Look at engine carefully re intake etc... B4 opening anything. I think you can see that sheath w/o paying 4 hrs for the drop.

and there were no symptoms of marbles in can noise?

None at all. It was running fine.

you should be able to pull it out fine.... hopefully. GL

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YEEEUUUUP!

Please update as soon as solution confirmed. Close-up pictures of IMSB would be awesome too. Thanks.

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Sounds like a lot have experienced that - what about IMS affects the cam timing etc... If you don't mind (thankfully) my ignorance?

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I'm not quite sure as well. Maybe another member can shed some light on the subject. Meanwhile the work begins today and as long as things go according to plan I should have it back Friday. It's been 3 weeks and I really miss her. Yesterday I was on youtube listening to different porsche exhausts. Nothing beats the growl of a flat 6!

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It would have been interesting/helpful to know the error codes. IMS/IMS bearing is often the diagnosis but it may not be the right one. A VarioCam solenoid/actuator can go bad and cause the symptoms you describe. Absent any noise of the marbles in a can and absent any signs of bearing failure in the oil filter housing oil and the filter element... It is hard to imagine a real bad IMS bearing lasting as long as it did. I'm also having a hard time imagining how a failing IMS could account for a cam timing variability. While it is true the crank drives the IMS (via a chain) and the IMS drives the exhaust cams (again via chains) and the exhaust cams in turn drive the intake cams (chains again) unless a chain becomes so loose as the jump/skip a tooth the timing should not be adversely affected. What can affect cam timing though is if the solenoid (or actuator) fails. The DME adjusts the intake cam timing and then fails to detect the desired timing from the cam position sensors. Assuming the sensors are not bad (there are tests for this) the DME will log one or more error codes pertaining to cam timing. The engine will continue to run though it can run rough, experience a hunting idle -- in the case of my Boxster which went through this the rpms dropped to around 500 then climbed again and repeated this for as long (not long) as I let the engine idle. If the failure is a hard failure (compared to as was the case in my Boxster an intermittent failure -- after shutting off the engine, and clearing the error codes the engine started and ran just fine afterwards but I had it in to have the symptoms diagnosed and the engine repaired without any delay -- the engine may stumble or even die as the DME attempts to change the fueling to try to bring the O2 sensor readings into an acceptable range and gets the fueling too far out of whack. Anyhow, just my two cents (or less) worth. Sincerely, Macster.

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Thanks for the info. I printed your post and passed it along to the shop manager. Mechanics can be a little sensitive sometimes. Here are some pics from my visit yesterday.

Well it looks like the shop already got stuck into doing as they wish to your engine and whatever they say needs replacing will get replaced. Good job you have a warranty out on it. I think your warranty people will be involved and giving the go ahead with new parts or reconditioned ones. With any luck you just might finish up with a totally rebuilt engine even though it might have only been a simple thing as Macster suggested like a failed actuater. Would be nice for you to get hold of any old parts that they change so you can inspect the damage. Like the dreaded XXX bearing if it was changed. Anyway enjoy your new car to the fullest.

Under no circumstances is this an IMS failure. Please post the codes (ask the mechanic to just write down the numbers, we'll take it from there.) Without the codes there are just to many suspects.

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I stopped by the shop yesterday to see what the status was. He did say that it wasn't just error codes but that the timing was actually off which I saw for myself. Got there just as they were pulling the trans off and you could also see the area around the bearing enclosure definitely had seepage. Here's a pic.................... The way I see it is that if its something else he'll find it and in the mean time I'm getting the new LN Bearing for free.

What ya got there is a wet flange. Pretty normal really. Without the codes not much we can do from this end.

Not trying to be your long distance mechanic, just offering my thoughts on the situation. My comments are meant to provide you with some discussion points that a mechanic worthy of the name should be willing to discuss with you to your satisfaction. I can't recall if this has been done but it not removing the oil filter housing and carefully dumping its contents into a *clean* drain pan and looking at the oil and the filter element can help one determine what's going on. If the IMSB is going bad there will be signs of this in the filter oil and element. But you must be sure the drain pan is *clean* *clean* *clean*. A false positive at this stage can be an expensive mistake. Sincerely, Macster.

Check for debris in oil. How was cam timing shown to be off? We check for position of CAM slots relative to valve cover alignment by removing the cam plugs. If off then we pull the scavenge pump covers and inspect the cam locking bolts. This can all be done with engine in the car -- heck so can the IMSR. You can also pull the valve covers and inspect the cam chain rails, if one of those broke or chipped off, it would affect one sides timing. You can get one side if the IMS to one bank chain jumped. The only way to get both sides off is if the Crank to IMS changed relative position. We had 99 Boxster have the IMS sprocket slip, but I'm told that is only known to have happened on bicycle chain IMS's which were phased out somewhere around 99-2000. It is also possible that your timing chain tensioner wasn't working properly and you jumped a tooth, this would knock both sides off. However I would not think that it would have gotten better with just changing the CPS. Note it is possible that it jumped one tooth before (maybe bad -- but not catastrophic??) -- and now has jumped more than one tooth. Love to know the end result. thanks, mike

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+1

would love to know the result here ... I'm guessing mechanic found a minor vacuum leak and then sold an IMSB.

I'm stopping by the shop today to see whats going on. I'll definitely keep you guys posted.

Not a fan of aftermarket warranties??? I paid $2250 for a great warranty that my buddy sold me at his cost and EFG Warranty has paid out $5800 in claims so far. The last one was an arm wrestle for the vario cam actuator and selinoid but I won and there are 2 years to go plus almost 25K miles left on it.

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Which warranty do you have?

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this comment made my lump come up. I thought you were saying the LNE bearing failed and they were going to send you a new one. You dont have an LNE bearing and you are saying the ins company is going to do one. Just clearifing for other people who skim the post and dont read it from cover to cover.

Boy were you guys right. IMS replaced and engine is still cutting out. Finally got the error codes. P0335 Engine Speed Sensor Signal – Open Circuit P0341 Camshaft Position Sensor 1 - Signal Implausible, Short to Ground, Short to B+ Any advice is greatly appreciated.

Roger that. Crank and camshaft position sensors. I doubt both sensors went at the same time. Prolly wiring, or the whole DME went bad.

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Please excuse my ignorance but what is the DME exactly?

That's the ECU for your car, the "brain"

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Ahh. Thanks

I'ts prolly just the crankshaft position sensor (I'd replace this first anyway.) final answer ;}

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Actually that sensor was already replaced. Now they think the new sensor was faulty. New one coming in on Monday.

Replacing the crank sensor was the correct first move (based on time and expense.) Next I would go over the wiring very carefully. Ground faults, anywhere it looks like it rubbed, contact points. Beat on the connectors. Cam sensors are next. I just can't believe it's the DME. The durametric can yield engine timing waveforms which definitively diagnose which sensor has failed. Outside chance the crankshaft timing pulley needs to be torqued. Go back over all the connections to all the sensors. Beat on them until they start working. Or at least threaten them until they behave.

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P0335 Engine Speed Sensor Signal � Open Circuit Possible fault cause ♦ Corrosion in the connector ♦ Open circuit or short circuit in the wiring harness ♦ Rpm/crankshaft position sensor faulty. ♦ DME control module faulty P0341 112 Camshaft position sensor 1 - signal implausible Possible fault cause ♦ Loose contact ♦ Camshaft position sensor

faulty sensor... possible, not likely.... def wring out connections and plug wiring. My .02

I'm no expert in these things but I beleive the Durametric can tell you the history of the voltage these items are receiving. There have been other threads about chafed wiring causing similar symptoms. From what I've read, it's quite simple to diagnose if you have access to the Parametric or Porsche diagnostic equipment.

Pull the connector off the DME and arm yourself with a DVM, trace continuity and short to ground or 12V back to the harness connectors in the engine compartment. If that checks out, trace from the engine side of the harness connector to the sensor. Shouldn't be that difficult to find.

Still hoping to get word back on this one soooooooo bump.

I'm hoping as well. Still doing the same thing after the second sensor was replaced. Checking voltage and all grounds at the moment. Waiting to here back. This is getting very frustrating to say the least! I'll stop by the shop tomorrow to see whats up.

***UPDATE*** After doing several tests with various parts of the electrical system they noticed a spike in AC current right before the engine would cut out while driving. Consensus is the diode within alternator is bad. Alternator is being replaced today.....

That's great that you may have it sorted. Keep us posted and good luck! Cheers, Tom

After 2 months & $9,500 worth of work including 50+ hours of labor/diagnostics the problem has been solved. Fortunately the warranty covered the majority of it. The culprit was 1 wire in a harness above the transmission casing that seemed to be somewhat chewed by a rodent. Looking on the bright side I have an IMS upgrade from LN, new clutch, new alternator, & several new sensors. Picking it up later this afternoon. I'm more excited now than I was when I first bought it!!!!!

Awesome! Your patience is rewarded. Rats are a more common problem than you'd expect - heard of another vario-cam error that turned out to be rat chewed sensor wires.

Sadly all the diagnostic time doesn't raise performance ay higher. Oh well......

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hehehehehehe, got it on 1 try

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Do you think if you didn't have the warranty this would have taken so long?

Probably didn't make much difference. A shop that gets a rep for padding the warranty work will have a tougher battle with the warranty company adjuster in the future approving warranty claims. The shop has gone to the well now for a lot of money and my guess is this will hurt over time its bottom line more than this job helped its bottom line. Sincerely, Macster.

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Thanks for the update. As good as any place to put this: While you'll get a lot of ideas, and some really good ideas, about what may be wrong with a car from here and other sites, it really takes someone at the car with sharp eyes, ears and a nose and experience to troubleshoot some problems. Just to reinforce this: Anytime a car comes in with a problem out of the blue if the car sits unused for any length of time rodent damage has to be suspect. 'course, in your case this bit of sage advice comes too late. Sincerely, Macster.

Thanks for all of the suggestions guys. After 2 days of very spirited driving I have fallen back in love with it. Clutch is silky smooth and motor runs and sounds fantastic! There were times during the last 2 months when I was seriously considering selling the car as soon as I got it back. I looked at a couple of certified 997's. That's still going to be the next move but not until next year at least. For now I'm just going to enjoy it.

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I am mailing this thread to my Porsche service department. My 2011 Cayman S is currently in the shop for cam position error. Let's see if he can get it on one try . And thank you all for the excellent diagnosis. $9500 indeed.

For $9500...find a new parking space!!

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So glad to hear that it turned out well! Enjoy your car!