I’ve been having some strange problems with my car and I waslooking for some guidance on what could be the cause. I have a video thatcaptures one issue but the others I will list. I imagine whatever the rootcause is related.<o></o>

<!--[if !supportLists]-->- <!--[endif]-->Under WOT, the rpms drop and I feel a lack ofpower before it builds up again (as demonstrated in video when rpms drop andthen car surges)<o></o>

<!--[if !supportLists]-->- <!--[endif]-->At part throttle, the car stumbles and surgesbetween 2500-3200 rpms. You can hear DVs whistle <o></o>

<!--[if !supportLists]-->- <!--[endif]-->Under 4k rpms, there is noticeable “lag” in anydriving mode. It’s less noticeable in Sport Plus but very pronounced in othermodes. Feels like I'm dragging an anchor

<!--[if !supportLists]-->- <!--[endif]-->At part throttle when around 4k rpms, sometimesI get a “boost bomb” and the car hits real hard (as if I'm flooring it although my foot hasn't moved) then bleeds off boost and/orshifts<o></o>

I have been experiencing this since I went stage 2 and hadthe cf y-pipe, the IPD plenum, Forge DVs, and stage 2 tune done. I thought itwas the wrong springs in the DVs but I confirmed that wasn’t the case (yellowsprings with one spacer).<o></o>

I did a ~300 mile trip with the wife this weekend to AtlanticCity and it wasn’t enjoyable driving the car at all. It appears to me as theissues are all boost related since I can feel boost surge and hear it bleed offrandomly. Sometimes it feels like traction control kicks in for no reason andother times it feels like the car has a mind of it’s own. Boost will just spikeeven if I don’t modulate the pedal.<o></o>

Anyway, I was hoping someone could point me in the rightdirection. I’m hoping it’s just something stupid, but it's very frustrating. I have a track rental Monday and definitely don't want to run the car the way it is.

Here is the video of a 5^th gear pull WOT done at NJ Motorsports Park track event <o></o>

Thanks in advance,<o></o>

Chris<o></o>

<o></o>

 

Are there any error codes stored in the ECU? They can point you in a specific direction if you can figure out what they mean.

Your video shows the car making steady boost of 16 psi right up to where the video ends at which time it drops to 0. Did you lift off the throttle or did the boost just go "limp"? Is 16 psi about what you'd expect to see? Also, will the car rev to redline or does it shut down or shift prior to getting there?

Often times when rpms are unsteady at idle or get "hung" at a higher rpm that's indicative of an air or vacuum leak somewhere in the system. I suspect (but don't know for sure) that could happen further up the rpm band as your video shows. But, if 16 psi is about normal that might lead one to believe that everything is properly tightened and minimal, if any, leakage is occurring.

The two main diagnostic paths to think about are whether some part is failing or has failed (actuator rod, air leak, bad gasket, etc.) and needs to be repaired/replaced or whether the car is going into limp mode (pulls boost, timing, etc.) to protect itself. That could be caused by almost anything and can be (very) difficult to figure out. Since your troubles started around the time you changed the plenum and y-pipe, I would start with a close inspection of all the obvious parts and connections and do a leak test. Hopefully you will get lucky and find a leak or two that can be easily remediated or an obvious part flapping around in the breeze that can be replaced or repaired. Beyond that, the diagnostics can get complicated in a hurry and you'll probably want to enlist professional assistance. Good luck!

 

What year of a TTS do you have?

The first thing I would do is a boost leak test. Then go from there...

 

Looks like your clutch is slipping. That's why you would get a change in RPM with no change in speed.

 

Pray Tell, why would you conclude the clutch is slipping? RPM's are not going up under load; they are going down. Best,

 

It is a little weird, but the RPM change while the speed stays constant. Unless he is getting the car out of gear at 120 mph! Strange right?

 

2011 TT-S with 6k miles
That video was a 5th gear pull in manual mode, I let off at the end before redline. I could redline it no problem. The issues I listed make me think it is boost related. I almost wonder if I'm hitting a torque limiter or something.
To rule out bad octane, I had mixed race gas in but it made no difference.
I just ordered a Durametric yesterday so as soon as it comes in I will be logging and checking for stored codes in the ecu. I've yet to see a CEL or anything thus far, car just drives like crap

 

I just got a stage 2 tune as well last week. Having a bunch of weird issues myself. Car ran fine prior to the tune. Never had an issue until now. Curious to see how you make out with this.

 

Are you having the same issues? Can you pm me with what you are experiencing?

 

What everyone forgets is a tuned car makes more boost. More boost means more opportunities for boost leaks. I have owned turbo cars for years and on everyone of them I do a leak test regularly. This includes my TTS. When I did a ECU tune on my TTS the car ran great at first then started to run more and more sluggish. A Vbox run confirmed this with 0-100 MPH times nearing 10 seconds. Also my dash reading on PSI read lower than anticipated 11 instead of 18. I did a boost leak test and found the leaky hose and repaired and tighten clamps. The car instantly regain power and 18 PSI again. The car had no check engine light during the entire process. Durametric did read 2 codes that did not show up on my dash which referred to the low turbo pressure.


You can read about 1 boost leak here:


http://forums.rennlist.com/rennforum...turbo-car.html


In this case all the parts changed tells me it is a boost related issue. The IPD and Y pipe are all part of the charge piping... Also diverter valve is boost related and not to alarm anyone I have seen billet pieces leak before. I once ordered a billet DV for my car and the unit leaked worse than the stock piece it replaced. The way I found it was by doing a boost leak once again.

 

Not a boost leak...

 

Have you done a boost leak test? This to me would be the beginning then go on from there. Can you post the weird issues you are having this will help to assist in troubleshooting.

 

All of the stage 2 work was done by a Champion recommended dealer so I wouldn't expect them to incorrectly install the parts and have a boost leak. Nonetheless, I will be checking for one this weekend and doing some logging when the cable comes Tuesday.

 

1.) You can't assume parts would be installed without issue, regardless of vendor.
2.) Based on your post, I may check the Diverter Valves. The AM versions with the pistons will stick, and / or leak. I have one in my garage right now that is seized.

Good luck.
DC

 

I agree with therock 88. I am not suggesting that parts were installed improperly but even by nature of adding more boost the weak link show up. I have been wrenching on cars for over 30 years and this is from my personal experience.

1. Just because it is a billet diverter valve it does not mean it is leak proof or stick proof. I have seen many aftermarket DV's fail over the years on various car platforms. If I had any concerns about my DV leaking I would go dual "Tials" bov on the y-pipe since I have many high HP builds using them with no issues.

2. Higher boost will show up the weak points. I have seen lines get blow off see my link below this is what happened to me when I turned up the boost on my Turbo S. Also with increase boost many area's of leak could show up such as connection to the throttle body, intercooler etc... the only way to find them is do a boost leak test above your maximum boost pressure. As an example if your peak boost is 20 PSI I would boost leak to 25-26 PSI.

http://forums.rennlist.com/rennforum...turbo-car.html