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Thanks everybody! Life intervenes, and I’m going to use $ to solve this one with the dealership. They had the shop manager call me and explain.
main points he made:
- they had a lot of issues with vacuum lines on 955, but very rarely on 957. And easy to replace (and I can DIY this later if needed) skipping the lines unless they find a leak
- they test right off the pump. My low side is generating 5 in (instead of 23) at the pump.
- this mechanical pump on the turbos drives so many things with check valves etc, that it is nearly impossible to smoke test it. They have learned to test (and replace) the pump and work downstream from there if things continue to be wonky.
- he has seen low vacuum cause all sorts of issues, even non-code-throwing ones, and would not be surprised if replacing this pump in improves things we may not have even know were struggling, the intake runners work better, etc.
Just sharing what I’m hearing. I am certainly no expert!
Thanks everybody! Life intervenes, and I’m going to use $ to solve this one with the dealership. They had the shop manager call me and explain.
main points he made:
- they had a lot of issues with vacuum lines on 955, but very rarely on 957. And easy to replace (and I can DIY this later if needed) skipping the lines unless they find a leak
- they test right off the pump. My low side is generating 5 in (instead of 23) at the pump.
- this mechanical pump on the turbos drives so many things with check valves etc, that it is nearly impossible to smoke test it. They have learned to test (and replace) the pump and work downstream from there if things continue to be wonky.
- he has seen low vacuum cause all sorts of issues, even non-code-throwing ones, and would not be surprised if replacing this pump in improves things we may not have even know were struggling, the intake runners work better, etc.
Just sharing what I’m hearing. I am certainly no expert!
ok then just change those two parts, and you be good to go. The pump should take about 1.5 hours, and the brake booster line 5 mins. Just spend some time getting up close and personal with where the pump is located and the three bolts that hold it in place, then dive in..lol
Thanks everybody! Life intervenes, and I’m going to use $ to solve this one with the dealership. They had the shop manager call me and explain.
main points he made:
- they had a lot of issues with vacuum lines on 955, but very rarely on 957. And easy to replace (and I can DIY this later if needed) skipping the lines unless they find a leak
- they test right off the pump. My low side is generating 5 in (instead of 23) at the pump.
- this mechanical pump on the turbos drives so many things with check valves etc, that it is nearly impossible to smoke test it. They have learned to test (and replace) the pump and work downstream from there if things continue to be wonky.
- he has seen low vacuum cause all sorts of issues, even non-code-throwing ones, and would not be surprised if replacing this pump in improves things we may not have even know were struggling, the intake runners work better, etc.
Just sharing what I’m hearing. I am certainly no expert!
There have been numerous posts from parts swappers who changed the vacuum pump without any previous diagnostic work.
Bad move IMO.
The problem was not resolved, was it a defective pump or something else?
In my case Durametric displayed a small leak with no check engine, about a week later large leak with check engine light.
With the engine off I pulled vacuum on the line leading to the sport exhaust flapper actuator.
With about 5" engine oil was visible near the vacuum pump. A clear indication of a seal failure.
There have been numerous posts from parts swappers who changed the vacuum pump without any previous diagnostic work.
Bad move IMO.
The problem was not resolved, was it a defective pump or something else?
In my case Durametric displayed a small leak with no check engine, about a week later large leak with check engine light.
With the engine off I pulled vacuum on the line leading to the sport exhaust flapper actuator.
With about 5" engine oil was visible near the vacuum pump. A clear indication of a seal failure.
Replaced the pump, vacuum went from 5" to 20+"
OK, bless you rennlisters, I'm going to DIY this. I just cringe at shelling 3 hours' worth of labor at $220/hour for something that would take me, a rank novice, less. Even if the same or more time... sheesh.
So now, of course, I want to do this right. I'm going to order up a mighty vac from amazon or HF to take before and after readings, and to use when the next thing inevitably craps out.
Can someone provide idiot instructions for measuring from pump? I want to see the berfore and after? Do I literally just unplug from the back of the pump, hook up the mighty vac, and start the engine? Will it even run with no vacuum to anybody? Or do I tee off from somewhere?
(Again, apologies if this is already covered elsewhere. I did try...)
Also, FCP and Pelican are both selling revision 94811005007, but the latest is 94811005008. Does anyone know what the difference is, if it matters, etc.?
Thanks!
PS: Is this a topic that demands a DIY all written-up nice? If so, anyone wanting to edit and contribute to it, I may try to pull one together, to add my little bit to the forum.
I just cringe at shelling 3 hours' worth of labor at $220/hour for something that would take me, a rank novice, less. Even if the same or more time... sheesh.
May I suggest forgetting about the time it takes to get it done.
A lot depends on dexterity, patience and tools more appropriate for an Erector Set.
Success! I aim to write up a DIY. It would be titled: the right way, distracted by all sorts of stupid mistakes…
went from ~5-7 in HG to 20+. Interestingly, this was the 2nd replacement, as this car already had a non-Porsche pump in it.
@TRINITONY your advice was prophetic. The dealer said don’t bother with the brake booster vacuum connection line. Mine cracked upon removal. Elastic tape is holding it together for now, with a new one arriving tomorrow. First measurements post surgery were 15 in Hg, which had me pulling my hair out, until I tried testing with my thumb on the big nipple (not sexual), instead of leaving the line to the booster connected. Then it jumped to 23-25 ish, measured from the little nipple.
that’s better!
this may be my imagination, but it seems to make more power, over a wider band. I don’t think we have intake runners on the turbos, so not sure what might be affected by the availability of sufficient vacuum? Compression? Crankcase pressure? Total guesses.
Well, couple weeks ago PO455 popped up, I re-tighten the fuel cap, cleared the code and was hoping it would not come back.
I recently got P2181 (unrelated) ,cooling system performance code ,yes, I have to replace the stuck-open thermostat, so I scan the car every few days, just to make sure I am not missing any new codes before the repair, I can see PO455 pending again, there is a replacement seal available on Amazon, so I don’t have to replace the entire fuel cap, nice to have that option. Here is the link for the next guy:-)
I cleared the code, see if it makes any difference. My original seal was pretty banged up, as it was the original one, it seems it was time to swap it out anyway. Few days goes by, I get the pending code again.
I read up all the information on here and everywhere else, pretty cool, I have a pretty good understanding of the whole system now.
I saw a bunch of the PO455 videos, even the one with the compromised vacuum line behind the intake manifold. Most likely not the issue with mine as I zip tied the other end of the little elbow, keeping the line in place last time I removed the intake manifold, but good info and you never know.
So I order the pressure gauge as suggested and smoke machine, ready to do some troubleshooting here, I started with to scan for codes again, No code pending for PO455 today. Both EVAP monitors PASSed, So instead of measuring the pressure or smoke testing I decided to take the engine beauty covers off and take a very close look at the vacuum pump. Here are a few photos:
I can see dried up oil smudge, I touch it, looks fresh underneath, looks like I found the problem, right?
So my suspicion is it, vacuum pump is on the way out, I think, it would explain why the code is pending after filling up with gas, as the pump is having a hard time getting the system pressurized, the pending code goes away when it’s all up the required levels, so it’s only question of time before the pump cannot keep up.
I did not get to smoke the system or used pressure gauge yet as I came to the conclusions above, anyone is willing to second my findings? Any advice or recommendation?
UPDATE:
I replaced the oily Vacuum pump, I did NOT have to remove the intake manifold.
I discovered my main vacuum hose had a crack in it. Here is the P/N 955-355-579-30 for the next guy.
Unfortunately the CEL came back, I will get in the rear passenger side wheel well and do some testing this weekend.
UPDATE: all great, CEL is gone. EVAP monitor showing the perfect numbers again.
I smoked the system, tested the purge valve, and measured the vacuum with the gauge.
All good, tight and no leaks.
USER ERROR WARNING: When tightening your gas cap, just twist, hold the cap loosely and don’t press on it, three clicks and done. Just don’t get too psyched to avoid the CEL by pressing on the cap while closing the gas tank or it won’t seal at all to my surprise.
UPDATE:
I replaced the oily Vacuum pump, I did NOT have to remove the intake manifold.
I discovered my main vacuum hose had a crack in it. Here is the P/N 955-355-579-30 for the next guy.
Unfortunately the CEL came back, I will get in the rear passenger side wheel well and do some testing this weekend.
Hey my friend I've been reading up on you I have the similar problem with mine with the 4055 code I have a Panamera 2010 I changed the purge valve solenoil canister and it still giving me the check engine I'm following your footsteps you said something you going to check the rear to find out something there how did you solve your problem besides that hose you found to be cracked on the vacuum pump,, was anything wrong from the rear( leak detention pump) I don't want to go into taking off the intake manifold just hoping it's not that area,!?? thank you for giving me some of your knowledge of troubleshooting what you worked on ,I'm also going to check that hose you said like you said pass it on to the next guy can you reach out to me and tell me what did you find out to solve your problem thank you brother
Last edited by ecalderon321; 02-29-2024 at 07:07 AM.
10-25-2022, 05:13 PM
