Rodie

2006 997.1S - 64K Miles -- Could use some advise!

After not driving the car for some time (winter) I took it out yesterday as it was a nice day. Getting misfires on multiple cylinders (P0300, Random/Multiple Misfire, P0301 (Cyl 1), P0304 (Cyl 4), P0303 (Cyl 3), P0305 (Cyl 5.) Didn't get codes for Cyl 2 or 6 (at least not yet.))

I am speculating it may be old/stale gas as it may be ~3-4 months the gas has been in the tank (1/4 full) and I forgot to put any additive in it (dumb.) Perhaps it is something else, but I'd like to eliminate fuel as the car was fine when I garaged it a while ago.

The misfires led to a blinking Check Engine light, which I'm told could be damaging to the catalytic converters. The car had 1/4 of a tank in it, so I at least topped it off before I drove it home to get 3/4 of the tank filled with 'new gas.'

What to do now? I feel like if I put some additive in (Techron? Seafoam?) and drive it a bit more things may just work out. That said, I don't want to damage the catalytic converters in the process.....

Any advise on where to go from here appreciated. Hoping this is a minor issue but at least need to eliminate gas as a culprit before I move on to other things.

Thanks,
Rodie

cosm3os

Fill it up and drive.

ADias

No StaBil in the tank?

Bruce In Philly

I think gas gets blamed way too often. I stored a Datsun 280ZX Turbo in a cement mine located in Wampum PA for 7 years. No Stabl.... nothing. Darn thing started right up and ran fine.... no kidding. I thought I was in a Woody Allen movie.

Peace
Bruce in Philly

cosm3os

I'm guessing the engine management system in the 997 is a bit more sensitive than your old Z!

TheBruce

Others will likely have better advice but I would start with the simplest issue and work up from there: check your gas cap. If the seal dries out or its not tightened enough (clicked 3 times) you can get CELs and misfires.

I had an issue last week where I caught the plastic lanyard under the cap while screwing it on (the automotive equivalent of zipping your d*** in your pants). Instead of unscrewing it i just pulled on it to remove it. It still must not have been seated properly and that was enough to create a misfire. I didn't get any CELs but the engine surged a couple times when cold going up a hill at ~3k rpm. I pulled over, googled, removed and retightened the gas cap, all fixed.

The dealer was across the street when this happened so I popped in and asked their service advisor his opinion. He typically gives me **** advice but I still ask him anyway. Here was his comments:

1. He had never heard of the gas cap issue, despite there being tons of posts on it in RL.
2. Could be bad gas but was not likely in my case. More likely in yours since the car was sitting.
3. Could be bad coil packs and/or plugs. Seems unlikely in your case since its on multiple cylinders.
4. He said he rarely ever sees bad fuel pumps

For what its worth.

motopix

Not to mention ethanol plays havoc with fuel systems and gas containing ethanol at least appears to go bad much more quickly. Assuming the Z was stored with non-ethanol gas.

cosm3os

That's funny shiznit right there!

Rodie

Welp, I got a can of Seafoam and one of HEET and I figure I'll try one and then the other and just drive the car to run out the old gas. Will advise -- hopefully I'm not looking at something more 'interesting' -- but given my luck (and stupidity) I likely will be!

Thanks all.

cosm3os

Why would you continue to run out the "undiluted" bad gas, rather than dilute it as much as you can with good gas (i.e. fill it up)?

Rodie

I did top off the tank. Had 1/4 tank of old, got misfires, filled it, still got misfires for a very short period of time, and parked it full.

Added the Seafoam and I'll run it after dinner to see if anything changes. Hopefully I can run through the old stuff and have things return to normal (hopefully.)

Rodie

Smooth as silk! Not a single misfire and I went out an got on it for the first time in a long time. Absence makes the heart grow fonder. I love this car!

cosm3os

Good news

Petza914

It was definitely the gas. Has happened to me 2 different times when the 997 has had the same fuel in it for a period of 3 months or so. It will just fall on its face, then pick back up. Both times, running out the old gas and refilling it resolved the issue.
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bhvrdr

I got a bad tank in the S5 once and got random mult cyl misfire and pretty extreme "sputter" at gear change (aka, cyl suppression). I ran a full tank with HEET in it and the a full tank with BG44k and that did the trick.

Mike