Dark Helmet

No check engine, no oil warning, no other indications.

temps are fine.

oil pressure is "3" at idle, maxed under any load.

car has run well and run strong for over 3000 miles in the last 2 weeks... this morning it just decided to be a 150hp car and not a 325hp car.


ideas?

Dark Helmet

engine is smooth, no odd noises, just has no suds.

my assumption is that any engine-management failure will throw a CEL, and since I don't have one, I'm inclined to think it's a fuel filter/fuel pump issue...

the spark plugs are (I believe) original, but at 37K-miles, shouldn't cause a loss of power like this... there is no noticeable misfire.

no PSM lights, brake warning light... no nuthin'.... I've driven it about 15miles since it became symptomatic.

quick google search indicates these symptoms are not indicative of an IMS failure.

Dark Helmet

oil measurement says half-quart low... seems to consume about a a quart every 5K based on what I've seen so far.


exhaust doesn't smell like fuel, so its not "gas but no spark"

driven 25miles since it became symptomatic, still no CEL, which a MAF or o2-sensor issue should trigger. Engine runs smooth and quiet.



this would lead me to believe the culprit lies within one of the following:

-Fuel Filter/pump not flowing. would need to check FP levels at the rail to be sure.... google has yet to confirm/deny the existence of a FP test port. pump can't be totally dead as there isn't a primary/secondary, it's just one. so filter blockage/failure seems more likley there.

-TPS/electronic throttle malfunction. throttle not opening properly... one would think that a TPS failure would trigger an error code due to an incongruent input with the MAF signal, so that would make me thing the TB itself is to blame.... which seems easy to reach, but can't be cheap!



I would welcome any other ideas...

Ken968

Just a shot in the dark here but try disconnecting the battery waiting a few minutes and then reconnecting. I hear that the car throttle inputs can adapt to how it has been driven. So for example if grandma takes the 911 out and drives it regularly for a week or two, then you get back in and try to drive spirited the car may take a little to readjust from the granny profile. Again just a shot in the dark.

Ken

dbv1

It's in limp mode, you need to read the codes to find out why. We had this happen to a friend's car when we forgot to connect the cam position sensor accidentally. And yes, it behaves like it has ~150 hp when in limp mode.

Dark Helmet

^^^^ that makes sense except no CEL, I would have expected any fault that would trigger Limp mode would also throw a CEL.

Spiffyjiff

elaborate please? do you mean that you press on gas and, even when floored, it only accelerates at a slow pace, etc? like you only have 50% of your throttle/available power, etc?

su_maverick

Just try running a OBD and the same procedure to clear codes then disconnecting the battery and reconnecting. See if it goes back to limp mode or if it just needed a 'kick in the ***'

Dark Helmet

that's exactly what it does.

it's not choking and gagging, still very smooth, but an old SC would probably run circles around it. feels like driving an old Civic HF

neanicu

I would test the fuel pressure. It might be a weak fuel pump or a clogged up fuel filter.

LexVan

Do you consistently run your fuel level low with the warning light on?

Dark Helmet

It got low enough for the light to come one 12 days ago when I was coming back from Colorado... but that was (literally) over 1500miles ago.

that's the only time it's been down that far. usually fill it around the 3/8s mark.

PhilD

^^^This. It is very unlikely you will correctly diagnose the problem without pulling the codes and seeing what is going on. There are so many things that can cause issues on modern engines that you need more info to diagnose the problem correctly.

chsu74

Does the CEL light turn on? Have you checked that the bulb is working?

utkinpol

read codes. if engine pulls strong but only until 3K rpm - what is it, either a maf sensor, or variocam, or, well, it may be long list. start with disconnecting battery for 5min, then drive it again, and read codes.