Hey Guys, I'm hoping to tap the wealth of information and knowledge on this forum. I just got my graphs from a dyno run last week and have included them below. The runs were done RWD only on a Dynojet 424. The basic history is the car (01 996tt, 42k mi, Tip) is new to me, appears completely stock, and is throwing overboost codes. Previous owner allegedly hasn't done anything to the car.

In spite of my searching, I haven't had any luck finding graphs showing a/f and boost with the hp/torque curves. I'd love to have a bunch of HP, but not at the expense of lean a/f ratios. It's like the race motor builder saying "fast reliable cheap, pick 2".

My car seems to be sensing the boost and/or detonation and pulling back the timing around 3800.

I've got new DVs in hand, and am probably gonna get a 5 bar FPR. I'm gonna keep the stock exhaust.

Does a flash fix this with the above parts? What am I missing?

edit: run 2 is in 4th and run 5 is in 3rd

 

durametric tool will aid in diagnosing the problem. Not sure if it can tell if the car's been flashed, a dealer or indy with right obd2 scanner can tell.

13 ish a/f at wot does seem a bit lean. but Im no expert, Im sure others will chime in.

Have you checked the wastegates?

 

Thats a DEAD LEAN map.. How at Peak TQ is the car surviving at 15:1 AFR?? Its just amazing the abuse the Motor will take.. My guess aside from possibilities of mechanical issues is that the car is Knocking so bad down low at those AFR's it will never recover as it comes finally drop richer at the very end of the pull.. I dont know how the mapping works 100% but most cars drop into a safer map when they see Peak Boost & TQ and are DEAD LEAN.. You need the car looked at before you step on it any more..

Mike

 

17 psi = 1.16 Bar
That has got to be about the limit of a standard Turbo and actuator. I see no attempt by the DME to drop the boost from your graphs. This make me think that:
1. The last owner was a Subaru Owner and has wound the hell out of the Waste Gate control rods thinking it would give more power with more boost.The N75 control valve only has a 75% duty cycle might not be able to control the boost. I would have liked to see some boost control no matter how minimal though. Unless the rods have Maxed out!!
2. The N75 valve is not working and allowing max boost.
3. Both Wast gates have seized, or control pipes missing?

Note on your graphs for run 5 there is no early over boost peak on the graph and the line is level and at max engine revs the boost is still the same. At any other time I wish my boost graph would be so constant. When the Dme pulls timing you can see the power drop but absolutely no boost drop. IMHO unless the DME has been flashed it should have tried to pull back some boost. Unless it cant do so due to a problem.
Just a thought.

 

Start with boost problem first.
Check wastegates if open at stock pressure.
If yes check boost control equipments. (Solinoid, associate vacuum hoses&wire.)

 

Thanks everyone for helping me order my thoughts.
Since I saw the overboost codes, I've babied the thing. The only time since I got it that it was run hard were the dyno runs
The wastegate rods don't seem overly tight, less than an inch from the end of the rod.
I'll have to check if the control lines are intact, but on other older Porsche turbos if the control lines are off, boost is pretty much completely unlimited. Like blow up unlimited.
I guess the N75 doesn't throw a code if it's toast?

So, I'll check wastegate operation, make sure my control lines are there and then head on to the N75. Finally when my tuner shows up, I'll see if his computer can tell if I'm flashed. And I guess a Durametric is next purchase...

Thanks again everyone. I love this place!

 

The distance from the end of the rod to nut is around 10-11mm, stock.

Not sure if the n75 throws codes if malfunctioning. THere are 3 hoses that go to the N75. One that points towards the back of the car, goes to the lower diverter hose, the one that faces front of the car goes to the Y manifold and the one that points to the bottom of the car goes to a T then to both WGs.

what it does is controls air pressure to the WG, to allow higher boost and with out it, the wastegates would open around 0.4bar. so in your case, if this was the problem, it would have to be broken in a way to effectively cut off all pressure to the WGs.

https://www.6speedonline.com/forums/...rging-fix.html

 

When I had my intake done, mechanic put new hose to N75 instead of oe. It kinked and overshoost my boost to 1.5-6 bar.
So might be possible that your vacc hose kink or come out, bad N75, disconnected/loose wire.
Another, wastegate might get struck. GL.

 

Thanks again guys. Mad Ness, Thanks for the spec. I'll check the rod lengths when i get home and then run the vacuum lines for at least a visual check. Maybe i'll pick up an N75 for when I do the DVs.

I've got a small delay anyway as one of the DVs came without the 90 degree angle connector. I really want to get this sorted so I can play with this toy a little more.

 

This is a picture I've stolen from a previous post from Kevin (umw)
This is oem setting :

 

Does anyone here use a Wideband O2? Which ones work well with a recall or recording feature?

 

this car stock has widband. durametric can log