avader906

Few comments and observations:

Toby&Nick: As you both know doing diag on tuned turbo cars is always PIA. (though nothing compared to debugging DME code itself.....)

997 VTGs boost control is radically different from 993 (and non-VTG cars). Boost is controlled electro-mechanically through vanes. Additionally, there is huge safety margin built into the used vanes angles (if I recall correctly stock uses sub 40% of available band - due to heat). Boost is adjusted in open loop with ECU - which has much more sophisticated approach to calculating effective air mass and both adj. requested boost and ignition params. By design - actuator controlled turbine is much more responsive in terms of dynamics than conventional spring-based boost control (wastegate/pneumatic solenoids etc).

(on VTG cars) You should not hear DV dump boost in WOT - if you do hear boost dump - you have vac leak - VTG's will try to compensate dynamically - leading to instability in flow - possibly misfire. ECU monitors req. boost vs actual (and values are available in durametric). Overboost is dealt with compressor wheel speed control - (some say that) RS zeros that off (then relying only on vane control (modified) parameters - easy to make mistakes if turbine/compressor profiles are changed from OEM).

In terms of magnitude of numbers - say you have 5 bar spike in boost from compressor - odd's of that going through throttle body and into intake runners is close to 0 - you will have anything UP TO throttle body potentially blowing. Components with most pressure drop to start with (coolers) that will suffer most.

You can hear pitch change as vanes open up. You can replace stock DV's (even if car stock - we saw stock tt's with them failed) - requires turbos out. To check DV's you need to go into overrun from WOT (ie. lifting from full throttle at 4,300 in second gear) - one of signals would be the car jerks forward (that's DV's not dumping boost as fast as requested). To note that with 997 DME and durametric you can log requested boost vs actual to check for leaks.

With regards to hesitation and limp mode - these are misfires. I can easily reproduce it if I reset ECU and drive in sub 5deg C ambient. ECU needs time to adjust (based on (modified) base tables) - RS left a lot of things in open loop. To be honest - some say they left some of VTG specific (as opposed to non-VTG) parametrization unused.

Regarding "torque limiter" - I'm afraid I dont understand what you refer to. Engine monitors each cylinder and will log misfires if individial cylinder and bank "power output" deviates - is this is what you are referring ? But then deviations are due to actual pre-ignition/detonation....

TTurbine: time to replace plugs (and/or coils)

TTurbine

Avader i just replaced all sensors and plugs/coils

In regards to the missfire i understand that it shows up in the durametric? but the only thing that shows up is the overboost fault code "upper liit value exceeded" that happens to be a code that is not in Porsche Piwis itself...

avader906

i think i've played enough with 600ps RS kit to affirm that there should be no hesitation - and what you mention indicates an issue - not related to the tune. Changed plugs/coils ? that (potentially) leaves clogged cats, burned 02 sensors, exhaust or vac leak, bad gas. maybe reset your ECU to start with....

PS: that you dont have PIWIS codes showing up with hesitation simply means this is related to the basic list of things to check (and say not variocam.... etc.). If you have a boost leak on 997 tt chances are you wont see any codes but have hesitation at max torque - and overspeed (overboost) *flag* on VTG's as it tries to compensate. Here logging requested vs. actual would help to confirm. PIWIS (DME) has specific section incl. misfire counter similar to over-rev stats.

TTurbine

O2/MAF sensors changed along with plugs/coils , car runs catless exhaust and no leaks..

avader , this hesitation only happens in cooler weather when the boost ramps up... for less than half a second then all is good... but when i accelarate from 2xxx rpms in 5th gear in colder than usual weather it goes into limp mode..

Why dont you try it with your car and see what happens?

avader906

all im saying this is not normal and not related to the tune. btw as mentioned in this thread - you should not be playing (apart diagnostocs) with your clutch and rods in 5th gear at 2k rpm if you want both to last......

my car is empty shell right now - undergoing track only conversion. i was lucky enought to drive around 5k miles over last xmass-new year - including -20deg C in alps. i had a few problems, traction aside - but -10degC highway pulls at max torque never showed any hesitation. same kit as you minus catless plus larger TB. i did blow few hoses and ended up replacing worm drive clamps with t-bolt (was pain to find t-bolts in tiny oem size) - not due to the boost but expansion/contraction of all hardware between cold/warm car. if you ever see your car on the dyno (even more so with stock engine mounts) you will have heart attack seeing entire intake tract move/jump 3-5cm under WOT - hence the reason for most vac failures in colder weather.

TTurbine

BTW thanks for the advice regarding dataloging boost vs boost requested i think its nominal boost on the durametric?

avader906

no prob dude - it's PIA when things dont run perfect..... it's in millibars so substr. ambient presssure.

note that i havent run mine with current config (pipes with 100cell tri-flow race cats) in sub 5-7deg C - compressor wheel overspeed is much more likely catless/race cats. But I would be very surprised RS programming was so at the limit that 2-3psi of less backpressure would overspeed the wheel. there is decent amount of safety on RS 600 PS kit - i know RS clients (with additional dyno by RS) - same hardware 630 PS.

Z06

I have no problems in cold weather, its stupid fast at 0c, wish it was like this all the time... wonder how much more power it makes?

The only problem I sometimes get is a check engine light during the hot summer days at idle, it comes up one bank is lean at idle..(think it was right side) could not find a leak, changed 02's going to try the EGT next... Cargraphic/RS say there is no chance its the cat or program.

avader906

Check exhaust for leaks (if it's idle only) - if you have rs/cargraphic manifolds and track the car - chances are they wont surive long - like any other tracked exhaust. EGTemp sensors damn pricey (denominated in pads).

TTurbine

Dont want to hijack Toby's thread but thougt i might aswell share this information..

I dataloged the car today from 5th gear 2xxx rpms till peak torque.. it was 18 degrees ambient.. i wanted to see what exactly causes this overboost fault code when i try to bring the torque from 2xxx rpm in 5th gear...
The results were pretty terryfing car went into limp mode at around peak torque at 39xx rpms after it misfired a few times... it also was running way to lean compared to the 2-4th gear redline acceleration results i had after i reseted the ecu from the limp mode... MAFs reading was like 1000kg of air at full boost? compared to the 16xxxkg number i get when i accelerate from gear to gear..

Sounds like an ecu glitch that RS have left...?????

avader906

I understand you do have a mechanic, team or someone who can help you repair the car ? Problem with internet is that everyone has an opinion. The only opinion that counts is that of the guy who works on your car. IF you want to hear someone on the internet (say an "expert") support your theories - nobody can persuade you as to otherwise.

Remarks are as follows:
1. You did not datalog as much information as is relevant to make a diagnostic. 6speed has few threads on durametric - what variables to log.
2. There are few books around on bosch injection / ECU tuning - including introduction of how things work. It is math heavy stuff - you have to either leave it to those who's job it is or learn up.....
3. Your car has problems not related to the tune. Given "you changed everything - it must be the tune" it's pretty difficult to help you. You even can be correct - ECU could be fried (it happened to Toby...).
4. If the car goes into limp mode - you have to bring it to the dealer or your mechanic for full PIWIS scan and diagnostic.
5. Did I mention who important is to have a good relationship with your mechanic/team ? People driving these cars are often an easy target....

PS: given your log - ECU struggles to adapt injection and runs rich - indicating vac/mechanical problem from the list I've mentioned. You need more logs to at least have an idea which area to look at a)vac or exhaust leak/MAF/O2/EGT sensors related b)turbos (inc. bad actuators) c)plugs/coils/cyl leaks d)engine (including variocam, lifters etc. /ECU). You P mechanic will be able to follow the manual to diag the problem independently of the aftermarket tune.

Nick Wong

Best thing you've written on this thread. Just make sure the guy working on your car really knows what he's doing...

TTurbine

Thanks guys will see how it goes on... as it seems there is no problem from gear to gear acceleration and he power is still there 100-200kmh in 6.6 secodns better than my previous 6.7 sec time

Its just when i try to bring the torque as Toby said in 5th gear... i beleive he has a similar problem ..?

TB993tt

Our problem sounds exactly the same however mine does not throw any Durametric codes neither does it go into limp mode and when it did the misfire thing (not going there anymore after blowing manifold) it was quite dramatic like an ignition limiter but not linear, sounded like it was cutting idividual random sparks and the motor was trying to pull through this rev range area.

Moe, you have the original programming done in 2008, mine was done afresh with the Bosch guy so maybe different/better but still goes out of range at that peak torque area with high air mass ambient conditions IMO it is to do with the boost control like I said before and likely to be the way the mechanism tries to reduce boost, these big VTGs and agressive mapping just spool the engine up too fast for the mechanism, works fine in lower ambient air masses but the programming is not able to cope with the higher masses which come with cooler ambient temps - when mine was programmed it was always over 25C.....

Avader, you had the big VTGs on the 600 kit right ? I think you never got into this range we are talking about, you mentioned a few times that you don't agree with 2K rpm and WOT so if you practice what you preach you would never get into this zone, do you not remember your VTGs making a shuffling noise right at peak torque ~3000rpm ? it is this noise which then becomes the misfire at cool temps

TB993tt

Some spark plug shots, not sure how much work they did, certainly 5000miles, possible a lot more.....

Last 30 miles was with intake manifold split open.