jealxndr

Anyone with experience on these codes?
PO300 - 507 Misfire Detected
PO301 - 508 Misfire Cylinder 1
PO302 - 510 MIsfire Cylinder 2
PO1250 - Boost Pressure Deviation Exceeds Limit Value
P1508 - 408 Function Monitor Torque Comparison
PO601 - DME Relay Porsche Fault code.

Driving the car in light traffic, 5 miles into a short drive. Just as I accelerate in 3rd gear, roughly 50 mph I get a engine light and the engine stalls. I pull over, check status and see the engine light "take in for Service" on the dash. I start the engine, it idles for 2 seconds , gasps for air, sputter and stall.

tow the car home and same, start idle for 2 and stall. Check the codes, clear the codes, try again and same response. the 2 second idles sounds great, and poof its off.
I'm getting gas to start, so DME is out.. I don't know whether to start with plugs and coils or if I can get some feedback on what other direction to go.

2003 996TT - 41K. Tuned/serviced 18 months/500 miles ago. Codes read with Durametric reader/software.

Any ideas?
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Jferrante

clear the codes, start with your MAF and then address coils and plugs if the misfire returns

jeanmarcboilard

Could be a boost leak. Easiest way to confirm or eliminate that is with a pressure test.

"02996ttx50

while the codes its throwing don't tend to support this conjecture(?) still the symptoms you've described are textbook for imminent fuel pump failure. particularly the "start ok, then idle, then it just dies" bit.

Macster

The plugs/coils would have to be awfull bad to make the engine act like that and to cause it to stall. The plugs (and possibly the coils) might be due but I think the problem is with something else.

While a failing fuel pump could account for the other errors and the behavior you describe the presence of that P0601 error code adds wrinkle.

P0601: Internal Control Module Memory Check Sum Error.

Reads like the DME is acting up.

Does the DME have the factory "tune" or an aftermarket "tune"?

To eliminate the DME I believe you'll have to have the DME scanned/checked/image verified by a shop with the proper Porsche diagnostics computer.

Is the fuel level about half way? One insidious problem is a siphon jet hose fails and the engine runs out of fuel at about a half a tank. The engine could start and run a bit with this problem but only a time or two until the fuel tank basin with the working jet runs dry and no fuel sloshes from the other basin -- with the non-working jet to the good basin.

How's the battery? Does it appear the alternator is charging the battery? If the alternator is not working the engine can run on battery power for a short time -- just a few minutes -- and then things start to go downhill. The engine runs poorly, misfires, and other seemingly unrelated error codes appear, then the engine dies. If the battery is allowed to recover and if it is in good health to begin with the engine might start and even run ok after a few minutes. But it doesn't have to.

You'll need to eliminate the lack of sufficient electrical power as a possible explanation.

Kevin

02996ttx50 I think has the most likely diagnosis >fuel pump failure and/or venture lift pumps. ..

Second would be a intake leak??

Third as Macster has mentioned, battery condition and if your voltage is falling below 12,2 volts