badabing

What's the preferred way of driving to test if you are getting correct boost? I have been concerned about this for awhile.

I've already done/changed/checked everything including full tune up/ new boost sensor, new n75 frequency valve, boost hoses, turbos etc.

Think I might need to adjust the nut behind the steering wheel?

OverBoosted28

Not sure on "prefered " way to drive and test it, but I'd be on a nicely paved, deserted straight roadway so all your attention is on shifting at full boost and watching your tach & boost at the same time.

993tbo97

I am then another one of those 5 suffering the same problem. The boost doesn't build up and peaks at 0.6 - 0.7 (factory digital gauge) and the car feels bit lazy... What is strange that sometimes the car works perfectly. When the car works, the boost gauge pops to 0.8 right after 3k and stays there to redline. The car was in dyno few years ago and was adjusted to run at 1.0 bar.

Pry

Tried an external boost gauge and it shows exactly the same boost as the factory digital gauge. The boost gets up to 0.5 bar and really struggles to get more. Also checked the diverter valves and according to this test they should be working ok.

WingChun

Have You carefully checked the turbo ends of the boost hoses?

I had the exact same problem that you are experiencing, it would only boost to 0.5 or maybe very rarely 0.6 bar.

When I checked the hose clamps at the bottom, on the turbos, it was loose on the left side but ok on the right.
This air leak was enough to cause the pressure drop and once tightened it boosted straight upto 0.8 at around 3000rpm.

OverBoosted28

You might need to re-train the DME. Make sure you have your radio code. Disconnect battery and let it sit for a few. Reconnect and then take it for about 45 min drive. During this drive you need to vary the revs. almost like resetting the readiness codes. This will tell the DME that you're asking it to check all sensors and systems by the manner it's being driven. First is a cold start and then let it idle for 10-15 mins. Then drive 8 miles at 2200 rpm. Then 5 miles at 2500 rpm. Then 8 miles at 1800 rpm. Park it and let it idle for 3 mins. You'll need a pretty deserted road to do this so some dingbat won't be up your rear wondering why you're driving so slow. If this doesn't reset everything and your still in"limp mode" you will unfortunately be looking at some serious work. Good luck

DRPM

IF the gauge is reading right I would do a smoke test on the intake and boost hoses/connections first.

I had similar problem a few years back due to a cracked connection hose right at the cool side inlet to the turbo...hose clamp over tighten and tore thru...had some hesitation during acceleration too.

C4S993

My newly acquired '96 TT exhibits liitle to none kick-in-the-pants-turbo-kick-in. Had it PPI at Autohaus Pa and they said turbos were good to go. But car lacks kick that I would have expected (drove a '96 TT in late 1990s and it was awesome), mine is quicker than my N/A 993 but slow compared to past confirmed 993 TT test drives. No error codes, no smoke, past owner new turbos installed. No obvious leaks, bar .2 at idle; rarely moves higher than .2 !

OverBoosted28

If I am correct you should not show any boost at idle. If it's stock it should start to spool up and read on your gauge at about 2500-3K rpm and stay at .08 bar through the next shift. You may be running into the same issue as op and have to chase down a leak of some sort ( vacuum/boost) in your system.

C4S993

Took her out to day and found that there is another world past 4k (3rd gear and upward) in my newly acquired '96 TT; almost scary ! Seller put 996 tires on her and I felt them just about ready to let go (and I was going straight). Hit .8 BAR and saw for a flash .0 BAR and .1 BAR but still idles at .2
Later this week I get to use the garage and with midrise determine if either actuactor is froze.
This car exhibits scary quickness. No BAR increase (above .2) until just tad of 4k in 3rd gear and then all hell breaks loose ! Never got past 4th gear ! I would have lost traction in 5th/6th.
The turbos' kick comes on gradually and not like a drunken sailor did in a '89 TT I once test drove.

OverBoosted28

C4S993....I have zero clearance K24's and I don't get into boost until about 3700-3800. Then it comes on strong all the way through the remainder of the revs. The PO may have put K24's in when they replaced the turbos.

DiegoR

Mine start to boost or "kick" arround 4k-4.4k RPMs. Sometimes when I go WOT, I don't feel the usual "kick" , just feels like a N.A. engine and rev up until the redline. When i shift, the next gear could or could not do the "kick"...it's like if my byspass valves were leaking sometimes (have check them and seem to be sealing & operating good) or maybe a sensor that says the ECU to retard the timing or something else but my 0.8 BAR display is there when I feel both, the kick (normal to me) and when is not present. I even took a friend for a spin and he beaing seated on the passenger side felt the "no kick" situation in one of the pulls I made.

But I do get full boost though...

C4S993

Later this week I will post some pics of the turbos and hopefully determine what I have. Hopefully the brain wasn't tampered with. I do not prefer late curve kick. Another problem is PO went with larger 996 wheels and at scary speeds car feels less than confident. PO installed PSS9 and they feel too soft (settings wise). Ride lacks the rawness of my tighter 993 C4S with PSS10 dialed in at #1. Latter sticks like glue no matter what; will not break loose. Newly acquired 993 TT suspension feels like it cannot handle 100+

Knight

I'd def start off by looking into your alignment settings.

Pry

Does the limp home mode always light up the check engine light?
Is it possible to be in the limp mode without having the CEL on?