[ike84]

Ike

Hey Blue,

I have been fortunate enough to not have had this issue happen to me. What I know about them is limited to what I've read on the forums, but there are a ton of posts about Vac leaks!

p1128 and p1130 are the codes most often associated with vac leaks, 28 being bank 1 and 30 being bank 2. its misleading because these codes read out in the durametric as if there is an o2 sensor issue, but what (i think) is actually happening is that the sensors are either reaching their lean limit.

the bank 1 issues seem to be more common. this is because the portion of the vac accessories connected to that bank (via the plenum or resonance tube boots) are numerous and tend to develop problems. this includes the vac cannister, the sai controls, the resonance flapper acutator, all the hoses and check valves that run between then, and (I believe) an additional line that runs to the transmission on the tiptronics. the worst part about these is that they are all virtually inaccessible without removing the plenum +- resonance tube and sometimes the runners as well.

the only vac that runs directly off bank 2 to my knowledge are the brake booster line and the fuel pressure regulator valve. the brake booster line is very robust and i can only think of 1 thread where someone had an issue with it. ive never heard anyone having an issue with the fpr valve or its connections.

the other vac-dependent systems are the AOS and the EVAP system, both of which come into the plenum just after the TB. The AOS system is what it is, no need to rehash that. The EVAP system can cause problems but it is almost exclusively related to the stuff under the right front fender (mainly the check valve) and are pretty uncommon. The most common "EVAP" issue isnt actually EVAP related at all, and that is the fuel tank vent valve goes bad and causes issues with fueling and occasionally causes weird stuff on hot startups.

in a lot of instances, 1128 and 1130 come up together. sometimes its because of a massive vac leak. some posts that I can recall traced that issue back to the MAF and derbis in the airbox or honeycomb before the MAF, although I couldnt quite figure out why that triggered those codes (unless it was moreso that the DME didnt find the O2 sensor output to jive with what the MAF was reading so it faulted the O2 sensors instead of the MAF)

anyway, thats most of what ive learned in trying to cobble together the info over the past few years. if theres something specific about the vac systems that you want to know more about, I'm happy to give more info if I know it. it drives me nuts that porsche does such a ****************ty job of making this information public like audi and vw do.

I think this would be a really good thread to post to get the community's experience. Unfortunately though I think that a lot of the older guys who ran through these issues are no longer around very much.


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