I had some weird things going on with my car this afternoon. Some background info - I have a 2002 996tt with 34k that I purchased about 3 months ago. Car came with a tune and fabspeed exhaust. The previous owner bought the car almost 7 years ago from the original owner with the tune on it and was never told who specifically tuned the car.

Since I bought the car it has always hit 1 bar strong with no issues. Well today I decided to head down to some backroads to enjoy the great weather. On the drive down on the interstate everything was normal. Right as I was getting to the back roads I noticed I shifted to third and all the power wasn't there. The car wouldn't go over 0.8 bar. It would pull hard for half a second like normal until boost got to 0.8 then it was almost like it would plateau and not pull as hard. This went on for the 30 minutes or so until I made it back to the interstate. I assumed I had a boost leak.

Well once back on the interstate I was cruising in 6th gear and floored it, all of a sudden power is back and boost goes straight to 1.3 bar. I test in 3rd, 4th, and 5th and all would go straight to 1.2 bar. These were not spikes, it went there quickly and held strong. Same results all the way home.

Never were there any codes, limp mode, etc. Again, I have never seen over 1 bar. Weather was around 70 this afternoon, I have been out in much colder. What could be causing this, tuning issues? I do have some logs that I made a while back before all of this I can post up if that would potentially be of help.

I am looking at upgrading turbos soon so was already looking around for a tuner. Should I do this sooner, is it potentially dangerous to be driving it as is?

Thanks for all the help.

 

i'm going to guess that your momentary inability to hit higher than .8 was more road/driving conditions, rather than an issue. can happen to the best of us

 

That is definitely a fair assumption. But it honestly was like someone flipped a switch and all of a sudden it was down on power and would go over 0.8. This continued for easily 30+ minutes. I just assumed boost leak the whole time. Then add in the significantly higher boost levels than ever before it makes me wonder if something really is going on.

 

since you dont know much about the car... a good pressure test would be a start- from the turbos... all this before any upgrades...
I would make you do a data log as well, then start with tuning and or turbo upgrades..
you do not want to do anything until you know whats happening to begin with.. one major issue many forget to take care off... later it gets more complicated...
markski

 

last time i had a similar series of events, was in ambient summer temps of 90-100+ so seeming boost discrepancies can happen for no other reason than ambient conditions, and it's common on the learning curve to experience this and see it as a possible *issue*. once the weather temps went back down.. my boost went *back* up. having said that.. in my favored driving conditions of fast canyon carving, i rarely see over 1.0, whereas 1.2, or even 1.3, is more of a wot flat road event. if ya know what i mean.

if it continues to happen? i'd then investigate the expert advice you've just been given by a reputable tuner lol. otherwise chalk it up to learning the car. just part of the joy

 

So I took the car back out last night to see if it was still acting up. Weather was around 60 degrees and was on the interstate the whole time. First few pulls I'm seeing 1.2 again in 3-5th gear. About 5 minutes later I try again and it all of a sudden won't go over 0.8 3-5th gear. Then about 5 minutes later I try again and it's back to hitting 1.2? Obviously there is not a leak and something else is going on. Anyone have any idea what could cause this? Could it be the tune that is on my car?

 

Could be a multitude of issues, most likely NOT a tune issue. You have an 11 year old car and probably do not know what maintenance was done on it. Hoses, clamps, connections, solenoids, etc get gunked up/split over time.

Your best bet, if you are not doing it yourself, is to find a reputable shop and have them pull codes - may be a code logged even though your check engine light is not on. Otherwise have an expert diagnose. Based on my experience could be a solenoid going out, diverter valves needing to be cleaned, repaired, split F hose or other hose/clamp. My advice, if you are going to keep the car....Save up your pennies and have your shop go in deep one time doing a full vac/boost test. Replace anything that is suspect. If you plan to mod down the road -this is the time to do silicone hoses, aftermarket DVs, wastegates, etc. After you do some mods, your weak spots will surely show up.

Labor is not cheap each time a shop goes in...ask me how I know - I paid for this stuff about 3 times over.

 

Car came with all records from previous two owners. Both spared no expense and it does have aftermarket diverter valves. After some more reading it sounds like the N75 solenoid is likely the cause. Looks like a cheap easy fix, I'll probably tackle that this weekend. Going to scan with the durametric this evening to see if there are anymore clues there. Thanks.

 

It's not your n75 most likely its your hoses that are split on the 3 ends of the n75.

 

remote not easy to say...all above said is correct and have to be checked

but i would check wastegates rods and maybe one waste gate goes strong if turbo heats up (stay open a little at hot conditions)