Stalls at temperature, only when coming to a stop.

[wywyatt]

I've just bought a beautiful 150k miles 2000 base, and she's having some trouble after a 4 hour roadtrip.

Beginning the car, there's a rough idle from 600-800rpm and backfires if I gas it.

When the car warms up, it stalls! Usually only when returning to low RPMs, or coming to a stop.

[wywyatt]

I recently had some post-cat o2 codes, but I've replaced them and now have no codes on my cheap OBD reader - definitely wouldn't show all the same codes as a durametric.

After the stall, it struggles to start but the rpm meter does bounce

Also recently realized the previous owner had drilled holes in the aos - I assume to relieve pressure after failure, so I've replaced that with no changes to the issue.

I've also unplugged the MAF and restarted the car, but had the same symptoms.

Could someone point me in a direction to start a diagnosis? I can't find many examples on the forum where it only stalls when warm.

[Bill Ladd]

Have you checked your fuel pump relay and fuel pump?

[mikefocke]

Treat your self and you car to a diagnosis by a Porsche knowledgeable person with a Porsche specific (Durametric, Pst2, PIWIS) tool. You'll learn more and be spared randomly throwing parts at the problem.

Join your local Porsche club as they usually have someone with the tools and knowledge and are willing to help new owners.

I've sometimes advised choose your mechanic before you choose your car.

[wywyatt]

Originally Posted by mikefocke

Treat your self and you car to a diagnosis by a Porsche knowledgeable person with a Porsche specific (Durametric, Pst2, PIWIS) tool. You'll learn more and be spared randomly throwing parts at the problem.

Join your local Porsche club as they usually have someone with the tools and knowledge and are willing to help new owners.

I've sometimes advised choose your mechanic before you choose your car.

Well if the legend himself advises it, that's what I'll do! Thanks btw for your website, I've used it extensively already I've got a guy who's going to take a look and only works on Porsches. I'll update with what he finds out.

[wywyatt]

Got a Porsche shop to look at it, guy was super nice. I would recommend flat-edge if you're near Savannah or Bluffton.

This is what I was able to write down during a phone-call, and I'm not the most familiar with all thing's "car".

Cam deviation was -8 (no indication as to which bank) for the limited time they could run it. Every tube on the AOS is taped up or replaced with a custom job, there's an aftermarket fuel regulator (I think it was regulator, but I could've remembered what he said wrong), and the oil fill tube is taped together. Lastly, its running super rich, possibly a fuel injector problem. I'll probably have RC Eng clean them up for me, but I'll wait to get the codes from the shop first.

The good news; Fuel pressure was fine!

I'll get a more complete list when I go to actually pick the car up, but basically looks like vacuum leaks to fix (easy, just a lot), an air/ratio issue (maybe related to vacuum?) and a camshaft issue (dear god, why).

So... is the camshaft issue worth the trouble for a car with 150k miles? The interior and paint are in great condition and worth saving, but only up to a certain price...

I read once here that the cam deviation is going to be super out of spec until the car is properly driven and warm. Is this true? And if so, even up to -8?

[tcoradeschi]

So, in general, not bad news, as I read it.

You clearly have vacuum leaks to clean up. Getting the injectors out, IIRC, is a bear of a job, so I would revisit that thought later. How did the determination that it is running very rich come about?

Your belief that checking the camshaft deviations should be done with the engine at temperature is correct. Discuss that with the shop to see exactly what they did. Typically that is caused by worn actuator pads - replacing those is DIY-able, but is around 4.5 wrenches out of 5 on the difficulty scale.

[wywyatt]

Thanks tcoradeschi, I don't think they let the engine warm up to properly measure the cam then. I dropped it off with less than 1/8th tank of gas left, and got it back today with almost the same amount, just a little less

He's a very nice gentleman but I think they may have not put much effort into my car when they realized the state it was in compared to the rest of the beautiful cars in their garage (a modern cayman, and I counted at least five very well kept 911's from 1970 to today. color me jealous!). He didn't charge me anything, so nothing against them, just wish there was a shop for us little guys


Gonna take a look at the oil fill tube and then I'll get around to replacing all the AOS hoses when they come in. Pelicans got the lower vent hose for just $57 from HT! Not bad. Wish me luck removing the passenger intake and plenums to install that... Most people online say you would have to splice the tube and rejoin it otherwise (yuck!)

[wywyatt]

Well, progress is slow. I'm stuck on how to replace the lower AOS vent hose, the one that runs under the intake manifolds.

I can't find somewhere online where it's confirmed as possible with the engine in, and I'm not in a spot where I can take the engine out. Any suggestions?

Picked up a used durametric off Facebook marketplace, I’ll update again shortly.

[wywyatt]

Holy smokes! The $50 durametric I got off FB marketplace actually works! Shoutout Bethany from VA! It was a pain to get the software running on win11 though I'll say. Jeez.

The camshaft P1 devation is -8.5 and camshaft p2 deviation is -8.8 *with the engine cold and off*. Sounds like that mechanic didn't let the engine warm up to read that. I'm going to put some gas into it and see how that changes. Would be super if someone could pull their cold values so I can compare.

I've got a code for the fuel pump relay (P1124) and the MAF (P0102), but I've unplugged and attempted to run the engine with both of those out at separate points in the last week, so I'll clear those and see if they pop back up.

"Supply voltage" is a steady 11v with the engine off, that doesn't seem right? Drops to 10.x sometimes.

[tcoradeschi]

Unless you have the engine running, the Durametric numbers for deviation won’t tell you anything. The value is the difference between what the engine controller commands the camshaft adjustment to be with what it is, as I understand it.

Does the 11V value agree (more or less) with what a voltmeter will read at the battery?

Do I assume that you figured out how to complete the AOS replacement?

PS: Thanks for the tip on Win 11. My Durametric laptop is the only wintel device we own and is still on Win 10, as the hardware won’t even take 11 unless I jump thru a bunch of hoops.

[wywyatt]

The AOS was replaced easy, I'm just researching to see how to do that lower hose now without dropping the engine.

I put some gas in from a can today (fresh from the same gas station as normal), put the cap back on and went to start... nothing. The lights turn on and somethings clicking in the engine bay, but it won't crank.

EDIT: Jumped it and after just two minutes of charging, it started up just like normal. New battery time! And time to check for draining I think. Maybe this whole thing is a bad ground issue. Really weird because I have no battery light or codes related to the battery... ???