The overboost issue came back after 150 miles of the driving following hard battery reset. During the 150 miles, it boosted perfectly at 1.0-1.1 bar, then it was like a switch was flicked and it was back to 1.3-1.4 bar.

The car has had 3 full boost test at Porsche and a Indy, nothing hardware related seems to be a problem. Hoses are good, wastegates are good, ect. The ECU reset seems, in my mind, to indicate it's the computer only causing this overboost when something got screwy following the initial hose break, so Switzer recommended I flash it back to the stock file and see if it boosts properly at .7-.8.

I did the stock flash, it completed successfully, but immediately got a ABS and PSM error light when turning the car on (I guess normal but they should go away after driving a bit when the system relearns). However, I was capped at .2 bar and the car felt like it had 100hp immediately after the flash. 15 minutes later, the check engine light came one. I cleared the CELs with Durametric6, let it sit overnight, turned it on to idle for 10 minutes to full warm and tried another drive. Same .2 bar max, way down on power, and CEL came back on. So now it's back in the garage.

So now what? Do I try flashing the tune file again and see what happens? I'm really stuck here guys, and not able to drive my Porsche any more ! Attached are the fault codes and messages per Durametric from last night. I have no idea what they mean or indicate. Perhaps somehow that flash to stock was corrupted despite it successfully completing? There isn't anything that was messed up or problematic on the flash to stock. Your help is MUCH appreciated!

 

Print this out and give it to them as an "FYI":

https://www.6speedonline.com/forums/...o-oh-dear.html

 

I would take the car to Switzer - they have a fantastic reputation for a reason, and it is their tune on the car.

 

Take it to an expert. You have a line hooked up incorrectly, your N75is failing, or you have a wastegate that is sticking closed or is misadjusted. All of these can result in a catastrophic engine failure.

Switzer is close....

 

Porsche (MAG) had the car twice, two full boost tests, new hoses, replaced N75 valve, replaced diverter valves, then reinstalled stock diverter valves and stock n75 to check if the new ones were bad, wastegates operating fine, still overboosting. Took it to AutoAssets (porsche indy) and they did the same hardware tests and full boost tests and gugage pressure readout tests, another 3 hours of labor, EVERYTHING checks out fine hardware wise. They reset the battery, it stopped overboosting for a couple hundred miles then started again, so Switzer advised flash back to stock to see what happens. That resulted in ABS/PSM cel, .2 bar max now and a CEL after 10 minutes of driving.

Trust me, I want Switzer to look at but 3 hours drive each way and they need the car for an entire day is not "close" and spending two days in Cleveland is not easy for me at the moment, especially with random bad weather. I guess it's mostly my fault and I'm going to have to suck it up and do this, but I am going to flash it back to the tune file today to see what happens before I drive there. I really can't comfortably drive it on the highway as is in seemingly limp mode anyway.

 

be a pain in the ***, and I'm guessing most shops aren't thorough enough.

I'm in the process of doing this myself, I've found some bad check valves, leaky BPV's, etc. etc. Waiting for parts has been a bigger pain in the ***. My car really was NOT exhibiting any issues or throwing codes, I just wanted to do it after I replaced the coils and plugs, figured I may as well go through everything while the bumper is off.

Get yourself a pressure testing setup from Marski, as long as you a decent air compressor, metric sockets, jack, and water bottle you should be good to go. Maybe another Porsche enthusiast with experience in your area would be willing to assist.

Good luck.

 

maybe you have a leak between n75 valves and wastegates

check your wastegates with only 0,1 - 0,2 bar maybe one leaks at low pressure at the rod...result is a boost spike

reason is a small cut at the diaphragm....at high pressure the diaphragm is sealed at the wall and you dont find a leak ...at low pressure it leaks sometimes and wastegates dont open



this check is quick done....

 

Flashed the car back to the tuned file, CEL's disappared, boost back to 1.3 bar. Doing some more research, it seems this overboost is usually tied to N75 valve when everything else checks out (as that is what directly controls boost.) https://www.6speedonline.com/forums/...rging-fix.html

I'm doing some detective work in my head and all indicators point to Mag putting in a faulty N75 valve when the original one was fine, then failing to remove it when I instructed them to do so....

1. Initial problem: I lost boost pressure from 1.1 to .4 bar.

2. MAG originally replaced the N75 valve only when I took the car in b/c they failed to find the split diverter tube (it was a BIG split, like 2 inches long).

3. After this, boost went from .4 to .6 or .7 immediately, yet the split was still there in the diverter tube, it was just magically boosting .2-.3 higher after this N75 was put in with no other changes. Although I told MAG the car was tuned and should be at 1.1 bar, they saw .7 and thought it was fixed and had me pick it up even though it was still under boosting.

4. Next trip to Mag, they found the split tube (diverter tube with 2 inch split) and replaced it and replaced the Y tube as well (not sure why Y tube replaced, old part was fine --- I still have it and original split diverter tube). They also installed Evom Billet DVs I requested put in as an upgrade while they were in there.

5. Immediately after this trip, car was overboosting to 1.3-1.4 bar and has done so since.

6. Another trip to mag for another full boost test and wastegate test and guage readout test. Found no problems at all. After this, I told them to keep the car, REMOVE (1) the Evom DVs and put stock back in and (2) remove the replacement N75 valve and put the stock N75 valve back in. I was explicit in advocating how I believed the N75 was at fault b/c it's initial .2-.3 bar increase with the still split tube, and now with the replaced tube, it's still .2-.3 too high. MAG did remove the Evom DVs (I have them in a bag) AND told me they replaced the stock N75 back in and gave me the N75 box with part inside. Car still overboosted to 1.3-1.4 bar after this.

It is my suspicion that in this above trip, Mag never put the original N75 back in, and the replacement one they put in is somehow faulty and causing the overboost issue. To further support this, looking in the n75 box, the N75 valve in there is quite dirty and looks to be a 10 year old stock part, not what you would think a 1 week used part would look like.

7. Considering my flash back to stock was a failure with CEL's and limp mode, then flash back to the tune file today still has the overboost, I'm going on the assumption that MAG put in a faulty N75 replacement valve and did not remove it when I instructed them to, then gave me misinformation that it was removed. I'm going to swap the dirty N75 I have in the box with the one in the car and see what happens. Not sure if I can do this myself or not, especially if the weather gets really cold before I get to it. https://www.6speedonline.com/forums/996-turbo-gt2/206000-n75-diy-thread-overboost-surging-fix.html

 

CHANGE THE MAF, I had similar probs and NO codes changed MAF and solved problems., Mike

 

Boost spikes to 1.5 are hard on your spark plugs and MAF, indeed. Solve the over boost problem and you may find a few more issues . . . . . .

 

And I thought Porsche's were supposed to be bulletproof. Between boost issues, ignition switch failure, headlight switch failure, rear wing hydralic failures (mine is ok so far but it's obviously common), ect, there is a lot of bull**** that goes wrong even if the main engine/tranny are super tough. Sorry Porsche, for now, my Ferrari is winning the bulletproof race...

 

So did you get to the bottom of this???? Mike

 

It's too damn cold to be in the garage for a couple hours trying to swap N75 valves myself right now. I'll get to it as soon as the weather warms a little. I missed my chance last week with temperatures in the 60s!

I'll be sure to keep you posted if it was the N75 faulty replacement valve or not.

 

you can log the N75 values in Durametric...

 

N75 valve was switched (I had a shop do it), and problem remains, still overboosting 1.3 to 1.4 bars. .