Ima2nr

nobody likes to air their dirty laundry, especially over the internet... but I feel deperate!!!

I' looking for help from all of the Guru's...


In Sept this year I bought a Perfectly running car... a pristine '96 993tt RUF Turbo R

all it really needed was 1 new brake rotor... the old one was done...

so, I bought new calipers and rotors (the best brembo has) for all 4 corners...
I felt the car could use a fresh clutch (light weight too), so while it was in the shop why not get that done also... perfect logic so far.

that's when my good friend "while your in there" came to visit me...

He brought with him these items:
new plugs, wires, dist rotor button
MAF meter
entirely new engine harness
better diverter valves, silicone hoses, clamps, etc
a re-geared (GT1 ratios) transmission (thanks Brian Copan)
anti return valves for the turbo oil lines
oil change, brake flush, all new fluids (i left the old antifreeze, it was still green- the tech said it still taste fine) (j/k)
a new custom exhaust system :-)
an Innovate onboard data logger (DL-32) with dual widebands
and any other small wear items I cant remember right now...

here is the mystery...

the mechanics are stumped at this point...

the car cannot control it's boost, and it runs lean even at low boost...

it has stock engine internals except for RUF camshafts
it has a RUF installed fuel pressure regulator (its at 5.3 bar now)
it has RUF ecu programming
still has the RUF turbo's that have been there since 1996

nothing is diffrent other than a GLORIFIED TUNE UP>>>
(complete engine out, harness off, tranny gone for 3 weeks, you know ---basic stuff)

please help me diagnose what could possibly be wrong?
the boost frequency valve, secondary air pump, and such have all been verified to be plugged in correctly, and the tech can activate them with the computer (like the hammer?) but for newer Porsche's.

they have checked for vacuum leaks, too. fuel pressure is good. the boost problem has been verified with a mechanical and digital gauge- I have extra boost if anybody wants some! (you can only have all the boost that is over 1.2 bar, i want to keep the rest)

I'll consider it a gift to me from you for Christmas if you can help solve the mystery... it has been 3 WEEKS we've been trying to trace this issue, and I'm losing my sanity (and $$$).

I've had the car sine Sept the 19th and I've driven it once (800 miles from Indian to Atlanta... but it was only one trip)

thank you...

Kevin P

ca993twin

Kevin,

Dang. What a bummer. As I recall, you also changed the wastegate springs... can this be related to the issue? Certainly not the lean codition, but perhaps the boost issue? Also, the MAF electronics are very easily swapped... do you still have the old unit? Dang.

911/Q45

I'm betting that with the new harness and the data logger, some wires got crossed.

Felix

Does Ruf use the standard 993tt MAF?

ca993twin

phelix,

Yes, Ruf uses the stock 993TT MAF sensor.

ttAmerica RoadsterAWD

Hmmm.....cannot control boost, do you mean you get overboost conditions, or cannot get appropriate boost??, or is the boost all over the chart with no particular pressure to rpm association??

How is the lean condition being diagnosed.......A/F ratios? Exhaust temp? Tailpipe combustion color?



......could it be that the engine is fuel starved, producing lean/hot condition, which would limit boost to avoid a catastrophic event?? If so, then the question is what's causing the lean condition. Any chance you can get ahold of a non Ruf ECU and switch out just to see if the lean condition gets better (with the Ruf cams it wont perform optimally, but you will be able to see if it's the ecu if it corrects the lean condition under low boost).

With respect to the engine harness, it's possible to cross a few of the connectors as some connections are close enough to be connected wrongly (don't ask me how I know!).

Frank 993 C4S

I feel for you. Bought my car in Feb '06 and will get it back in 4 days after a "while we're looking at it" exercise gone wrong. My only recommendation is to look at the fuel system and make sure nothing is clogged that would cause the lean condition. Don't ask me how I know.

K964

How about a front shot of the chick in your avatar?

sonny1

Go back and install the original maf, and give it a try, also check vaccum hose routing toward the gates, you can check the gate valves if they are sitting correctly, best, Sonny.

Kevin

One interesting data point was while the wastegates limited boost the engine was running lean..

Are the injector firing correctly? I would look at the original wiring harness and make sure that it wasn't modified?? If you are running lean at .5-.6 bar of boost we have a fuel delivery problem. If the previous shop installed the incorrect NA wiring harness and applied power you could have knocked out the MAF? The MAF is at the center of this fueling/boost struggle. I would also install a known good 993TT ECU and check to see if it runs correctly.

Another situation that you have created was freeing up the back-pressure with the new exhaust.. You can run lean from that condition.

ttAmerica RoadsterAWD

Agreed. I'd say if a change of a known, well functioning ECU fails to correct the problem, then you probably have a problem downstream from the ecu......like the wire harness, or it's connections.

Wouldn't the new Porsche software be able to pinpoint the problem by accessing the OBD2??

Bill S.

Better diverter valves? What's that? The Ruf ECU needs to work with all factory parts except the 5 bar Fuel Pressure Regulator, turbos, BMC air filter and Ruf cams.

ttAmerica RoadsterAWD

Hi Bill !

Well, Bill, as a matter of fact, I have the fancy billet evo diverter valves on my car. Did them when I had my hydra-lock fiasco and seems to work fine. I can get loose in 3rd gear (cause I have shot visc. coupler).

Jaime

Ima2nr

RUFUS asked:
As I recall, you also changed the wastegate springs...

my best answer:
ok, we did put the wastegate springs in to begin with, but we swapped back to the stock springs to be sure that was not part of the problem...


TTAmerica asked:
Hmmm.....cannot control boost, do you mean you get overboost conditions, or cannot get appropriate boost??, or is the boost all over the chart with no particular pressure to rpm association??
How is the lean condition being diagnosed.......A/F ratios? Exhaust temp? Tailpipe combustion color?

my best answer:
the boost curve is smooth, it just overboost to 24.14 PSI peak at 4740 rpm and then it comes back down to 16.5 PSI and seems to be 'settled' there from 5700 rpm till 6800 rpm.
we have 2 widebands in the car--one died (I assume it melted?) on the last pull... the dyno guy had a tail pipe wide band probe (the aluminum housing on the tip of it started to melt too)

the boost problem is not all over the place, it is identical each RPM point on every dyno pull we did... i have a datalog, but i have no idea how to post the graph.
(i have dual wideband O2 sensors, they were both (cyl 1-3, cyl 4-6) reading the same)


RPM boost=(psi) (bar) A/F(1) A/F(2)

2000 2.03 (0.13) 14.07 14.05
2500 3.49 (0.23) 14.79 15.04
3000 5.91 (0.40) 13.73 13.64
3500 9.96 (0.67) 12.92 12.64
4000 18.75 (1.27) 12.19 12.13
4500 23.58 (1.60) 12.61 12.79
5000 22.29 (1.51) 12.01 11.73
5500 17.63 (1.12) 11.58 11.33
6000 15.91 (1.08) 11.50 11.08

(these numbers are WITH the stiffer wastgate springs in) - I took them out and my peak boost was about the same, but i did not get a data log on that run (i did not hit the record button- i'm an idiot)


we have also put the old MAF back into the car, it test the same with the porsche scan computer...

the kids are opening their presents from santa... my wife is telling me to get off the computer.

David in LA

I think that "chick" is his wife