Garagecouple

Hi all,

Chasing down a p1476 code which is "leak detection pump insufficient vacuu." Code persisted despite changing the leak detection pump. Code comes and goes.

My questions are as follows:

1. Is the cruise control vacuum driven? I notice sometimes drops a few mph when going up incline. May gove me a clue this may be a central vacuum problem.

2. Where is vacuum pump located on the 958.2 CAYENNE s?

I cant find any info anywhere and alldata does not support this model. Any help would be appreciated.

RAudi Driver

Is that the V8 in that model? If it is then the vacuum pump should be on the passenger side rear head

Garagecouple

It's the twin turbo 6

AnAlbumCover

sounds like a leak in the evap system somewhere if you already replaced the pump near the fuel filler area. Smoke test would be your best bet from here..

Garagecouple

My plan is to smoke test the vacuum inlet line off of the LDP and also test it with a vacuum gauge. Just wanted to see if anyone knew if the cruise control on these cars is vacuum driven, and also the location of the vacuum pump so i can smoke/check those lines as well. Cheers.

AnAlbumCover

I believe the vacuum pump is on the passenger side bank of the car, near the firewall. EDIT: I was looking at the V8. Looks like its directly at the back of the engine on the V6.
https://www.porscheatlantaperimeterp...811005006.html

New V6: https://www.porscheatlantaperimeterp...ct=10064643#35

I believe our cruise control is electronic speed sensor driven,

RhinoComp

Losing a few mph when in cruise control is a whole separate rabbit hole

Fortunately, it's a simple fix that just involves a firmware update at the dealer. Cost is one hour of labor.

twodollardoug

I chased the "evap leak" for a couple months. Then I replaced the battery (separate issue) and haven't seen the code again. Or any code since.

Garagecouple

Want to bump this thread

I replaced LDP with porache OEM and I still get the code. It comes and goes.

I vacuum tested the line at the LDP and I get about 10 with large swings. I smoke tested all lines and don't have any leaks.

Wondering if the 10 of vacuum is normal? I feel like the large swings shouldnt be happening. I have no other vacuum related issues. Who thinks I should replace the vacuum pump?

RAudi Driver

Does your car have exhaust valves. Not engine exhaust valves but exhaust pipe exhaust valves. If so check the hose that goes to them.

Garagecouple

I checked vacuum at the leak detection pump and it was bouncing around 10 erratically. I do not have exhaust valves. My next plan is to check vacuum right at the vacuum pump. I didn't know these could lose vacuum over time?

Garagecouple

I just checkedchecked directly from the vacuum pump. The needle is bouncing around so much you can't even tell what number it's hovering over. Tried uploading a video but won't let. Absolutely sporadic needle. Went ahead and ordered a replacement vacuum pump. Let's see.